97 gutenberg

 In  reality, fogs are nothing more than clouds near the surface of the  earth.

 When the ground is at a higher temperature than the air, it  produces fogs.

 They are also produced when a current of moist air and a  current of hot air pass over a body of water at a lower temperature.

  Consequently, you can easily see that fog will never form when it is  dry.

  xxx  HAIL  After rain drops have been formed and they freeze in their passage  through the air, they then become hailstones.

  xxx  SNOW  When condensation of vapor in the air takes place at a temperature below  32° F.

, a deposit is made in a solid condition, either in the form of  snow or hail.

 Snow is made up of crystals, most of which have great  beauty.



 Everyone should observe either by the naked eye or by a  magnifying glass the little crystals caught before they are broken.

 When  you see extremely large snowflakes in the sky, you can be sure the  temperature is very near freezing, for at this point the flakes are more  or less damp and the snow is heavy and wet.

 Now if there is a slight  wind, the crystals become broken and separate flakes unite to form large  masses of snow.


xxx
 Generally speaking, ten inches of snow makes one inch of  rain.

  xxx  DEW  If the temperature of the ground falls below the dew point of the air,  the air deposits on the cooler surface moisture in the form of small  drops of water, which we call dew drops.

 Where the temperature of the  ground becomes cooler than the air above it, a rapid cooling by  radiation on a clear night has taken place; and if the dew point or  frost point has been reached by the ground, the air just above the point  is several degre
es warmer.

  xxx FROST  When the moisture in the air that is in contact with the earth is  condensed above the freezing point, dew is formed.

 When below the  freezing point, frost is formed or deposited on the earth.

 It is readily  understood from this that the surface on which the frost is deposited is  at a freezing temperature, while the air above it may not be freezing.

  Naturally, you can expect frost when the temperature falls to a point 8°  or 10° above the freezing point.

 Clear, calm nights are favorable for  frost, because the absence of clouds helps radiation, that is, it draws  heat away from the earth.

 If there are clouds, it prevents this  radiation.

 THUNDER AND LIGHTNING  Free electricity is always in the air.

 During clear weather it is  generally positive; during cloudy weather it is negative.

 This  electricity is carried in the air by the moisture.

 As dry air is a  non-conductor of electricity, in fair weather the electrified particles  of air are insulated and therefore acquire very little intensity.

 The  clouds having been formed and being filled with moisture, form an  excellent conductor of electricity, which acquires considerable  intensity.

 It is a well-known physical law that two bodies having  opposite electricities attract each other, and those having like charges  repel each other.

 From this, two clouds having opposite charges rush  together and produce the phenomena, called lightning, which is  accompanied by an explosion called thunder.

 Often we see several flashes  of lightning and then hear several thunder crashes, which is caused by  only one section of a cloud discharging its electricity at a time.

  As a cloud attracts the opposite charge of electricity from the surface  of the earth beneath it by inductive influence, often we see a discharge  of electricity from the cloud to the earth, the charge usually being  received by such objects as hills, t
rees, church spires, high buildings,  etc.

 Bodies containing large quantities of moisture are susceptible to  strokes of lightning, as the moisture causes them to become good  conductors of electricity.

 Also trees on the outer edge of a forest are  more liable to be struck than those farther in.

  There are several forms of lightning, such as zigzag, ball, sheet, and  heat lightning.

  Zigzag lightning, as the name implies, follows an irregular course,  producing a long zigzag line of light, sometimes ten miles in length,  and is caused by the air producing a field of resistance to the path of  electricity, causing it to seek a path o
f less resistance.

  Ball lightning appears like a large ball of fire, usually accompanied by  a terrific explosion.

 This is the result of the bodies being charged  with electricity of great intensity, and travels in a straight path, as  it has enough strength to oppose any resistance placed in its path.

  Heat lightning is usually seen on warm evenings, especially during the  summer, and very often unaccompanied by thunder, due to the great  distance of the lightning clouds from where we are located, thus  diminishing the intensity of the thunder.

 The electricity of the clouds  escape in flashes so feeble as to produce no audible sound.

  Sheet lightning is a diffused glare of light sometimes illuminating only  the edges of a cloud, and again spreading over its entire surface.

  Ordinary flashes of lightning last but the minutest part of a second.

  Thunder is the re-entrance of air into an empty space.

 The vacuum is  created by the lightning in its passage through the air.

 The violence of  thunder varies according to the intensity of the electrical flashes.

  Because of the fact that light is transmitted almost instantaneously,  while sound travels at a speed of eleven hundred feet per second, the  sound will not reach the ear for some few seconds after the flash of  lightning.

 Average space of time between a flash and a report is about  twelve seconds.

 The longest interval is seventy-two seconds and the  shortest one second.

 Prolonged peals of thunder are, in some cases, due  to the effect of echoes.

 These peals are especially noticeable in  mountainous countries.

 The echoes are also produced by the reflection of  sound from the clouds.

  Thunder storms are distributed over certain sections of the globe,  occurring most frequently in the equatorial regions and diminishing as  we approach the polar regions.

 Within the tropics, where there are trade  winds, thunder storms are rare.

 Thunder storms are common in warm  climates because evaporation supplies electricity in great abundance,  and thus precipitation of the air is brought about.

  [Illustration:  Fig.

 11  ]  xxx TORNADOES  Tornadoes are caused by the air becoming abnormally heated over certain  areas.

 Likewise, caused by a difference in pressure.

 Tornadoes are local  whirlwinds of great energy, generally formed within thunder storms.

 They  are most easily distinguished by a funnel-shaped cloud that hangs from  the bottom of the larger thunder cloud mass above it.

 The funnel is  formed around a violent ascending mass of whirling winds; its diameter  sometimes reaching several hundred feet, being larger above than below,  the winds themselves covering a greater space.

  [Illustration:  Fig.

 12  ]  The whirling funnel advances generally to the east or northeast at a  rate of twenty to forty miles an hour, accompanied by a deafening noise,  destroying everything in its path.

 The path is usually less than a  quarter of a mile in width.

  The winds in the vortex (the apparent cavity or vacuum formed in the  center of the whirling winds) of the tornado attain an incredible  violence, and due to this fact houses are shattered, trees uprooted, and  human lives lost, besides other devastatio
n of property and animal life.

  It is, therefore, the vorticular whirl that causes the destruction  produced by tornadoes.

  Tornadoes are more frequent in the southern states than anywhere else in  the country, and occur in the warmer months.

  The velocity of the whirling winds in a tornado increase towards the  center, and it is because of this that the point of danger is only a  small distance from the funnel cloud.

 The direction of the whirling  motion is from right to left.

 From the appearance of the funnel formed  in a tornado, it looks as though the currents were descending from the  cloud to the earth, when in reality the currents are ascending.

 The  ascending current draws on the warm and moist air near the surface of  the earth for its supply, and this inrush of air in a spiral form into  the low pressure core made by the higher whirl constitutes the  destructive blast of the tornado.

  Tornadoes approach rapidly, and it is therefore almost impossible for  those who happen to be in their path to escape their violence.

  A tornado at sea is termed a water spout.

  xxx  RAINFALL  You will recall a preceding statement that evaporated humidity turns  into water when it becomes cool below a certain point.

 (See page 14,  Effect of the Sun.

) A given amount of air will hold a certain amount of  moisture.

 For example, let us assume that a cubic foot of air (see Fig.

  11) is saturated, that is, it is holding all the water it will retain.

  Now if this cubic foot of air is cooled, it will contract, and as a  result there will not be enough room to hold both the air and moisture,  so the excess moisture will leak out.

 (See Fig.

 12.

) The result of this  reduction in temperature causes precipitation, simply because the air  cannot sustain the water that is in it.

 Therefor, at any time when  moisture in the air has reached the point of saturation and a chilling  takes place, due to the air becoming cold, rain follows.

 This may happen  as a result of air rising into higher places or cooler levels, or  through its contact with cooler surfaces.

 WHY WE GET SUCH HEAVY RAINFALLS SOMETIMES AROUND MOUNTAINS  The air becomes thoroughly saturated.

 When air is comparatively warm, it  will expand, and this air, which is heavily saturated is brought up by  breezes onto the mountain range, which is cold, causing the air to lose  its heat and contract and really force the water out of the air.

 The  same principle applies to sea breezes bringing rain.

  xxx WINDS  Winds are caused as a result of differences in temperature between the  various layers of the atmosphere.

 A certain amount of air becomes heated  and rises, and as explained before, expands.

 As the air expands, it  becomes lighter, and because it is light it goes upward toward higher  regions.

 It also flows from hot to cold countries.

 A good illustration  of this is the sea breezes.

 If you have lived around the seashore in the  summer time, you will have observed that during the hot part of the day  the winds generally blow from the sea toward the land.

 At night the  direction of the wind is reversed, that is, it blows from the land to  the sea.

 Why? Because the land during the day retains its heat, while  the water diffuses it.

 What is the result? The air on the land expands,  becomes light.

 The air over the water being cool, it does not expand,  and the result is that it presses toward the land.

 At night the land  loses its heat more rapidly than the water, so that it is not long  before the land is cooler than the water, and when this happens, the air  over the land, which has become cooler, presses seaward.

  xxx KINDS OF WINDS  =Mountain Breezes=: Caused by the heating and cooling of the hills and  valleys.

  =Avalanche Winds=: Winds that are in front of a landslide, caused by the  movement of the snow forcing the air in front of it.

  [Illustration:  Fig.

 13  ]  [Illustration:  Fig.

 14  ]  [Illustration:  Fig.

 15  ]  [Illustration:  Fig.

 16  ]  [Illustration:  Fig.

 17  ]  =Volcanic Winds=: Due to volcanic eruption, which produces an outrush of  air.

  =A Squall=: Due to the sudden disturbance in temperature.

  =A Simoon=: A desert wind.

  VELOCITY OF WIND  The wind blows a great deal harder on water than on land, because on  land it meets with various obstacles, whereas it has very little  friction on the water.

 THE FORCE OF THE WINDS Wind blowing at 20 miles per hour has a force of  1¼ lbs.

 Wind blowing at 35 miles per hour has a force of  6 lbs.

 Wind blowing at 50 miles per hour has a force of 13 lbs.

 Wind blowing at 75 miles per hour has a force of 28 lbs.

 Wind blowing at 90 miles per hour has a force of 40 lbs.

  xxx  DAY SIGNALS  [Illustration:  Fig.

 18  ]  [Illustration:  Fig.

 19  ]  [Illustration:  Fig.

 20  ]  [Illustration:  Fig.

 21  ]  [Illustration:  Fig.

 22  ]  [Illustration:  Fig.

 23  ]  xxx NIGHT SIGNALS  [Illustration:  Fig.

 19A  ]  [Illustration:  Fig.

 20A  ]  [Illustration:  Fig.

 21A  ]  [Illustration:  Fig.

 22A  ]  [Illustration:  Fig.

 23A  ]  xxx NAME OF WINDS  Beaufort’s scale, used in preparation of all Weather Bureau wind  forecasts and storm warnings.

  FORCE  DESIGNATION  MILES PER HOUR  0 Calm From 0 to  3  1 Light Air  Over 3 to  8  2 Light breeze (or wind)    8    13  3 Gentle breeze (or wind)    13    18  4 Moderate breeze (or wind)    18    23  5 Fresh breeze (or wind)     23    28  6 Strong bree
ze (or wind)    28    34  7 Moderate gale    34    40  8 Fresh gale     40    48  9 Strong gale    48    56 10 Whole gale     56    65 11 Storm    65    75 12 Hurricane    75  The following method of transmitting weather signals by means of flags  was use
d for a number of years, but the newspapers now convey the same  news to the interested public:  1.

 A square white flag indicates fair weather.

 (See Fig.

 13.

)  2.

 A square blue flag indicates rain or snow.

 (See Fig.

 14.

)  3.

 A white and blue flag, half white and half blue, indicates local rain  or snow.

 (See Fig.

 15.

)  4.

 Black triangular flag indicates a change in temperature.

 (See Fig.

  16.

)  5.

 White flag with a square black center indicates cold wave.

 (See Fig.

  17.

)  When No.

 4 is placed above No.

 1, 2, or 3, it indicates warmer weather;  when below, colder; when not displayed the temperature is expected to  remain stationary.

  The following flag warnings are used along the Atlantic and Gulf coasts  to notify inhabitants of this section of the country of impending  danger.

  =Fig.

 18.

 The Small Craft Warning.

= A red pennant indicates that  moderately strong winds that will interfere with the safe operation of  small craft are expected.

 No night display of small craft warnings is  made.

  =Fig.

 19.

 The Northeast Storm Warning.

= A red pennant above a square red  flag with black center displayed by day, or two red lanterns, one above  the other, displayed by night (Fig.

 19A), indicates the approach of a  storm of marked violence, with winds beginning from the northeast.

  =Fig.

 20.

 The Southeast Storm Warning.

= A red pennant below a square red  flag with black center displayed by day, or one red lantern displayed by  night (Fig.

 20A), indicates the approach of a storm of marked violence  with winds beginning from the southeast.

  =Fig.

 21.

 The Southwest Storm Warning.

= A white pennant below a square  red flag with black center displayed by day, or a white lantern below a  red lantern displayed by night (Fig.

 21A), indicates the approach of a  storm of marked violence, with winds beginning from the southwest.

  [Illustration:  Fig.

 24  ]  =Fig.

 22.

 The Northwest Storm Warning.

= A white pennant above a square  red flag with black center displayed by day, or a white lantern above a  red lantern displayed by night (Fig.

 22A), indicates the approach of a  storm of marked violence, with winds beginning from the northwest.

  =Fig.

 23.

 Hurricane, or Whole Gale Warning.

= Two square flags, red with  black centers, one above the other, displayed by day, or two red  lanterns, with a white lantern between, displayed by night (Fig.

 23),  indicate the approach of a tropical hurricane, or of one of the  extremely severe and dangerous storms which occasionally move across the  Great Lakes and Atlantic Coast.

  [Illustration:  Fig.

 25  ]  We have installed at our manufacturing plant a high-class weather  station, with equipment of the latest United States Weather Bureau  standard pattern, and are able to send out weather signals by wireless  from our own wireless station twice dail
y, at 4 P.

 M.

 and 7 P.

 M.

, to  all boys owning a wireless outfit.

 The indications are taken from our  own instruments.

 A description of these instruments and the method of  recording the indications will give you an insight into how the various  government weather stations arrive at their forecasts.

  [Illustration:  Fig.

 26  ]  On the roof of the factory is a weather vane (Fig.

 34) twenty feet high,  which is connected electrically with a register in our weather office.

  The register is of the quadruple type (Fig.

 45), and is capable of  recording wind direction, wind velocity, rainfall, and sunshine on the  same form or sheet.

 Thus, we know the wind direction and can deduce  certain things relating to the weather.

 Mounted on the wind vane support  is an anemometer (Fig.

 36), an instrument for measuring the velocity of  the wind.

 A rain gauge (Fig.

 49) on the roof catches the precipitation,  and for every one hundredth of an inch of rainfall, a small tipping  bucket empties its contents into a receiver and a record is made on the  form in the quadruple register.

  The same pen that records the rainfall also records the number of hours  of sunshine during a day, for it is not a common thing to have rain and  sunshine at the same time.

  A hygrothermograph (Fig.

 43) records on a form the temperature and  amount of humidity in the atmosphere.

  A barograph (Fig.

 44) records the pressure of the atmosphere.

 For  determining the pressure, we also have a mercurial and aneroid  barometer, which will be described later on.

  You can readily see that it is a simple matter to obtain the weather  indications.

  [Illustration:  Fig.

 27  ]  xxx CLOUDS  The numberless kinds of clouds makes it quite difficult to describe and  arrange them or illustrate them in any manner that makes it easy to  recognize them.

 Although some may be recognized from description and  with a fair amount of observation, you will be able to classify them in  their proper place.

 For instance, the thunder clouds most anyone  recognizes without any experience whatever.

  [Illustration:  Fig.

 28  ]  There are really four simple cloud formations and three compound  formations:  =1.

 The Cirrus Cloud.

= (Fig.

 24.

)  The Cirrus cloud is always seen high in the sky and at a great  elevation.

 Its formation is fibrous and it is particularly characterized  for its many varieties of shapes.

 It also has a marked delicacy of  substance and it is pure white.

  =2.

 The Cumulus Cloud.

= (Fig.

 25.

)  The Cumulus cloud is of moderately low elevation.

 It is a typical cloud  of a summer day.

 It may be recognized by little heaps or bushes rising  from a horizontal base.

 In summer-time we are all familiar with the  cumulus clouds rising with the currents of air in huge masses.

 They form  one of the most accurate indications of fair weather when you see them  gradually dissolving.

 Sometimes these clouds become very large, and,  while the texture is generally of a woolly white, naturally, when they  assume such large sizes, they gradually change in color to a darkish  tint.

  =3.

 The Stratus Cloud.

= (Fig.

 26.

)  This is the opposite of the Cirrus cloud, because it hangs the lowest of  all, in gray masses or sheets, with a poorly-defined outline.

  =4.

 The Nimbus Cloud.

= (Fig.

 27.

)  Any cloud can be classed as a nimbus cloud from which rain or snow is  falling.

  Of the Compound Clouds we have:  [Illustration:  Fig.

 29  ]  1.

 The Cirro-Cumulus Cloud (Fig.

 28), which has all the characteristics  of both the Cirrus and the Cumulus.

 The most characteristic form of this  cloud, and the one most commonly known, is when these clouds form small  round masses, which appear to be cirrus bands broken up and curled up.

  This is what people call the "mackerel" sky.

  2.

 The Cirro-Stratus Cloud (Fig.

 29), which is known when the clouds  arrange themselves in thin horizontal layers at a great elevation.

  [Illustration:  Fig.

 30  ]  3.

 The Cumulo-Stratus (Fig.

 30) is the cumulus and the stratus blended  together.

 Their most remarkable form is in connection with approaching  thunder storms, and are often called thunder heads.

 They rapidly change  their outline and present a beautiful spectacle in the sky at times.

  The Cirrus, Cirro-Cumulus and Cirro-Stratus are known as the upper  clouds and the others are known as the lower.

  ATMOSPHERIC DISTURBANCES  Disturbances of the atmosphere are classified as follows: Cyclonic, or  low area storms, or anti-cyclonic, or high area storms.

  [Illustration:  Fig.

 31  ]  The word "cyclone" to most people immediately means a terrific storm,  whereas in weather observing the cyclonic storm is not really a cyclone  or hurricane at all.

 It is a storm with an atmospheric pressure below  average.

 Particularly important is the wind that blows about this area,  which is always spirally inward, due to the rotation of the earth on its  axis.

 This is probably why it is given the name of cyclonic storm, for  it bears one of the important characteristics of a real cyclone.

 As the  wind is deflected and moves into the storm center, it turns to the right  and in the form of a whirlwind, spirally, moves around the storm center.

  (See Fig 31.

) It is this whirling process that has given it the name,  cyclonic storm.

  As the air rises over the point of low storm area, or, in other words,  the area of low pressure, and travels into the atmosphere, it is not  permitted to rise to any great height, because it is always acted upon  by the force of gravity and is being pu
lled back to earth again.

 We  assume that because of this fact, this rising air which has been pulled  back to the earth again piles up in certain places, causing the  barometer to rise.

 Such a center as this is known as a high barometric  center or the anti-cyclonic area.

 Here the circulation of the air is  exactly opposite to that of the cyclonic area.

  [Illustration:  Fig.

 32  ]  We are all more or less acquainted with these anti-cyclonic storms,  because in winter these great masses of air rise up from the warm areas,  pile up, and form high pressure areas over the mountains of Canada, and  soon this high pressure works d
own upon us as blizzards and cold waves.

  We have described quite minutely the movement of the wind about these  points of high pressure and low pressure and have shown you the map and  have illustrated the high pressure and low pressure areas, but there is  still another feature that is of gre
at importance to us, and that is the  movement of the storms and the fact that storms have a progressive  movement from west to east.

  These storms move more rapidly in the United States than elsewhere, and  are more rapid in their movement in winter than in summer.

 Their speed  is almost one half again as great.

 The average velocity of the low area  storm in the United States is about twenty-five miles an hour in June,  July, August, and September, and from October on they continue to  increase.

  xxx  LOW PRESSURE  We can summarize low pressure storms generally in the following manner:  They have a wind circulation inward and upward and are elliptical in  form.

 Their velocity varies from six hundred to nine hundred miles per  day, moving in the same general direction.

 They are characterized in  their eastern quadrants by cloudy weather, southerly and easterly winds,  precipitation, temperature oppressive in summer and abnormally high in  winter, falling barometer, increasing humidity and followed by clear  weather, ri
sing barometer, decreasing humidity and falling temperature  in the western quadrants.

  Buys Ballot’s law of winds is, that in the Northern Hemisphere if one  stands with his back to the wind, the low barometric pressure will be  invariably to the left hand; in the Southern Hemisphere the lowest  pressure is always to the right.

 This law explains one of the  characteristics of low pressure storms.

 AREAS OF HIGH PRESSURE  In speaking of low pressure storms we called them storm centers, because  nearly always they are of sufficient intensity to bear that name, but in  high pressure areas we do not speak of them as storm centers.

  The Buys Ballot’s law applies to anti-cyclonic as well as cyclonic  storms, that is, when one’s back is to the wind, the lowest barometric  pressure is at the left and the highest at the right.

 This is probably  understood by saying that in the cyclonic storms, the winds blow inward,  contrary to the hands of a watch, and in the anti-cyclonic they blow  outward, that is, in the same direction to the direction of the hands of  the watch.

  In the United States, the cyclonic storms are not as frequent as low  pressure storms, and it is safe to say that probably not more than  one-third of the entire anti-cyclonic areas can be classed as storm  areas.

  xxx WHY AIR RISES  Another very interesting experiment is to secure a long-stemmed glass  bulb (see Fig.

 32).

 Arrange this apparatus as illustrated, with the stem  of the bulb immersed in the water.

 The glass bulb condenses the air.

  When you first put it into the water nothing happens, but as soon as you  apply heat the air bubbles come out of the end of the tube.

 This means  that the air in the tube has expanded and part of it has come out  through the stem of the tube and the remainder is lighter.

 It is well to  remember, when air is heated it expands and becomes lighter.

 This fact  is extremely important to remember, because it has a great deal to do  with the important instrument, the barometer, which is used to measure  the pressure of the atmosphere and is an important element in the  question of humidity, as you will
 learn later.

 By this time you no doubt  have learned that:  1.

 Air has weight.

  2.

 Heated air expands, becomes lighter, and exerts less pressure.

  3.

 Cold air comes from the side to take the place of hot air that rises.

  When the rays of the sun heat an area of the earth, the air over such a  place expands and becomes lighter, naturally rising, and the result of  this is that the winds are produced by cool air moving in to take the  place of the heated air.

 This cool air moves in from all directions.

  When such a thing happens at any point on the earth’s surface, it is  known as a storm center, an area of low pressure.

 WHAT IS A CYCLONIC STORM?  Because of the rotation of the earth on its axis, a force arises which  tends to deflect to the right all motions in the northern hemisphere,  and to the left all motions in the southern hemisphere.

 The winds  flowing toward the storm center are turned to the right or left and move  in a spiral around the storm center.

 This system of whirling winds  around a central region of low pressure produce what is termed a  cyclonic storm.

 Storms have a tendency to move in an easterly or  northeasterly direction, and at a rate of from five hundred to seven  hundred miles a day.

 Cyclonic storms, although we look upon them as  being very severe, are very often mild and not of an intensive  character.

  WHICH WAY DOES THE WIND BLOW AFTER A STORM?  From the descriptions and experiments preceding, which illustrate the  development of storms, reference was made only to the winds blowing in  toward the storm center.

 Naturally the question comes to your mind: What  happens to them after the cold air has taken the place of the warm air?  They change to other directions when the storm has passed away.

 It is  because of this fact that we look for a change in weather conditions  when the wind changes-a very important sign that you will be interested  in later on.

  It is well to mention here a thing that is going to be very important to  us when we study the barometer, that is, the pressure of the atmosphere.

  Should the pressure of the air, which is normally at sea level 14.

7  pounds to the square inch, change, that is, become lighter, it would not  exert so much pressure on the column of mercury in the tube of the  barometer and the mercury would drop in the tube.

 (See Fig.

 7.

) On the  other hand, if the weight of the air was increased, that is, if it  became heavier, it would force the mercury to rise in the tube.

 This  should be quite clear to you, because it is the lightness and heaviness  of the air that is going to interest us more particularly than any other  part of the subject when we get into the study of the atmospheric  changes, what causes them, and the
 indications that lead up to our  conclusions.

 In order that this principle is absolutely clear to you,  you should perform Experiment 4, or if you have not facilities for doing  it, it is well to see it performed in any physics laboratory.

  Immediately you ask yourself: If air has such a tremendous pressure as  14.

7 pounds to the square inch, why is it that a weight of air amounting  to thirty-five thousand pounds bearing down on the average individual  does not cave the body in? Simply because air penetrates the body so  easily that it exerts as much pressure on t
he inside as on the outside,  and thereby equalizes itself.

 For instance, if you go down into a subway  or a caisson (a water-tight box or chamber within which submarine  construction is carried on under great air pressure to keep out the  water), where the pressure is sometimes greater than it is outside, have  
you noticed the effect this pressure exerts on the ear drums? As it  becomes greater, you may equalize it by swallowing, which allows the air  to get back of the ear drums through the Eustachian tubes, which lead  from the mouth to the inner ear.

  xxx  MOISTURE  Water vapor is always present in the air.

 EXPERIMENT NO.

 10  Expose a piece of dry potash to the air.

 You will soon discover that the  potash will dissolve.

 It has taken up water from the air.

 EXPERIMENT NO.

 11  Put a piece of ice in a pitcher of water and allow it to stand in a warm  room.

 You will soon notice that little beads of perspiration collect on  the outside of the pitcher.

 This moisture is air being condensed.

  Water vapor is part of the atmosphere.

 Some of it is always present in  the air.

 The amount of vapor that the air can hold depends upon the  temperature.

 When the temperature is warm, the air will hold more water.

  For instance, at 100° F.

 a cubic foot of air will hold 19.

79 grains of  vapor; at 80° F.

, 10.

95 grains; at 50° F.

, 4.

09 grains, and 32° F.

, 2.

17  grains.

 At 32° F.

 is the freezing point on the Fahrenheit scale.

  Air containing as much water vapor as it can hold is saturated.

 If the  air is suddenly cooled down, that is, if the temperature falls when the  air is saturated, air molecules are contracted, and it must give up the  water, which produces rain.

 The ocean and the Great Lakes are the source  from which the air gets its water.

 It rises into the air in the form of  vapor, that is, vapor rising from the surface of the water, and the wind  distributes it over the land.

 Condensation turns it into clouds, and  when it is over-saturated, or rather, when the temperature drops and the  air is unable to retain any more water, then it forms into drops of  water and falls as rain.

 When the clouds get into the air, below the  freezing point of the water, the drops of water are changed into ice  crystals or snow flakes.

  When the ice crystals are just at the point of melting into water, due  to the rise in temperature, the snowflakes lose their form and the  result is sleet.

  HOW CAN WE USE THESE FACTS?  So far we have described, in a general way, certain facts about the  elements of the air, such as temperature, pressure, humidity,  precipitation, evaporation, clouds, winds, etc.

, and these facts of the  elements enter into a very interesting phase of weather observation  which we will designate as prophesying without instruments or  forecasting by physical science.

 When we come to the more interesting  and scientific part of weather observation, we will drop the word  "prophecy," because the instruments that are used to measure these  elements are going to indicate certain things to us that will lead you  to more d
efinite conclusions.

 Hence, the following observations are what  have given an opportunity to the weather prophet or to those people who  have been credited with some mysterious power to prophesy what the  weather is going to be.

 They are not definite or conclusive, and they  cannot always be depended upon, but they certainly are significant and  interesting, and a description of weather would not be complete without  a list in chronological order of a series of phenomena or phys
ical signs  of this character that have lead certain men to gain quite a reputation  for prophesying what the weather is going to be.

  [Illustration:  Fig.

 33  ]  xxx  APPEARANCES  Various appearances that come in the sky.

  For instance, a good example is in the case of the thunder storm, which  can be determined at least a few hours in advance, by the movement of  the clouds and the forms they take.

 In every locality there is a  direction that clouds take that forecasts bad weather, and there is a  direction that clouds take that forecasts fair weather.

  When you see a halo about the top of a mountain, you know that bad  weather is expected.

 The same is true when a halo appears about the  moon.

 This indicates rain, or if the lower clouds break up and the upper  clouds, or a second light covering of clouds, are seen above the lower  ones, it speaks for continued bad weather.

 In some localities if rainy  weather is continuing for some time, and a certain change in wind sets  in, it will indicate that good weather is coming.

  These observations will be readily understood as being adapted for  certain localities and are not general.

 It is always necessary that the  observer adapt himself to these localities and study them, so that he  can make prophecies accordingly.

 It should be borne in mind that these  prophecies are only possible from one day to another.

  WHAT THE CLOUDS INDICATE  When high clouds are seen crossing the sun or the moon in a different  direction from the lower clouds, this indicates change of wind toward  the direction of the higher clouds.

 When you see hard-edged clouds, look  for wind.

 When you see delicate soft clouds, look for fine weather and  probably moderate breeze or high breeze.

 When you see gloomy dark clouds  in a blue sky, look for slight winds.

 When you see a bright blue sky  through fine clouds that are soft and delicate, this indicates fine  weather.

 When you see soft-looking clouds, you can expect less wind, but  probably rain.

 But when the clouds become hard and ragged, tufted and  rolling in appearance, stronger winds are coming.

 When you see small  clouds that are inky looking, look for rain.

 When you see light clouds  traveling across heavy hard masses of clouds, this indicates both wind  and rain, but if the light scud clouds are alone, you may expect wind  only.

 Misty clouds forming or hanging over the peaks of hills indicate  both wind and rain.

 If during a rainy spell they ascend or disperse the  weather is pretty certain to clear up.

 If there has been fine weather  and you begin to see light streaks in the sky which are distant clouds,  and they continue to increase and grow into cloudiness, this indicates  rain.

  SUNSET AS AN INDICATION  When the sun is setting and the sky in the west presents a color of  whitish yellow or radiates out at a great height, rain can be looked for  during the next night or day.

 Gaudy colors where clouds are definitely  outlined indicate probably wind and rain.

  Before setting, if the sun looks diffused and the color is a brilliant  white, this forecasts storms.

 When the sun sets in a slightly purple sky  and the color at the zenith is a bright blue, this indicates fine  weather.

 A red sunset generally indicates good weather, whereas a ruddy  or misty sunset indicates bad weather.

 WHAT THE SKY INDICATES  When you see a dark, dismal sky, look for rain.

 A sky with a greenish  hue, described as a sickly-looking sky, is an indication of both rain  and wind.

 A sailor’s sky, which is red in the morning, means either wind  or rain, and it makes no difference if the sky is cloudy or clear, if at  sunset it is rosy, it indicates fine weather.

 A gray sky in the morning  indicates fine weather.

 When daylight is first seen above a bank of  clouds, look for a good stiff wind.

 Wind is indicated if we have a  bright yellow sky in the morning, and rain is indicated if the sky takes  on a pale yellow hue.

 If the sky turns bright yellow late in the  afternoon, it generally indicates that rain is near at hand.

 Unusual  colorations, particularly of deep intense color, indicate wind or rain.

  The following appearances indicate a change in the weather: When the  atmosphere is clear and crystalline and the stars appear extremely  bright; when the background of the horizon seems to be pinned up against  the foreground; when the clouds form into
 delicate white film-like mist  way up overhead.

 (Fig.

 33.

) WHAT FOG AND DEW INDICATE  Locality has considerable to do with what the fog indicates.

 As a rule,  where you have fog, there is not much wind, and as a result it does not  indicate stormy weather, unless the fog becomes heavy with overhanging  sky, then it is apt to turn into rain, but a heavy fog with a light sky  indicates fine weather.

 A fog in the morning generally indicates a fair  day.

 A rising fog is a good indication for fair weather.

  [Illustration:  _Courtesy Julien Friez & Sons, Baltimore, Md.

_  Fig.

 34  ]  [Illustration:  Fig.

 35  ]  Dew is a pretty good sign of fine weather.

 When you can see and hear  with remarkable clearness, and everything is calm and still, it is a  pretty infallible sign that cold weather is due.

  Frost may be looked for on clear, calm, cloudless nights, when the  ground is apt to be cooler than the air.

 INDICATIONS FROM CIRRUS CLOUDS  When these clouds suddenly appear in the sky on a clear summer day, they  indicate wet weather.

 Especially if the weather ends turn upward, which  means that the clouds are coming down.

 When moisture in the form of  little drops cling to vegetation, it is a pretty good indication that  there is apt to be more rain.

  When the sky assumes the appearance of a gray mass and the sun is  observed shining through, it is a pretty good indication that it will  rain before night.

  When overhead clouds are thick and grayish and the lower surface of them  is lumpy, this is an indication of rain.

  Whirlwinds of dust are also indications of rain.

  xxx  THE MOON  The rings that we see formed about the moon are caused by the delicate  white clouds through which the moon is shining.

  [Illustration:  _Courtesy Julien Friez & Sons, Baltimore, Md.

_  Fig.

 36  ]  xxx  THE RAINBOW  The morning rainbow indicates that a shower is in the west, but if the  rainbow is in the east it indicates that the shower has passed over.

  BIRDS AND STORMS  There are certain actions of birds that indicate many things pertaining  to the weather that are interesting.

 It is probable that their ability  to fly into the air gives them a view of the horizon, that by instinct  they have been able to determine the atmospheric changes.

 For instance,  it is well known that if birds of long flight remain at their base, it  generally foretells a storm.

 The sudden silence of birds has been  referred to a great many times preceding a storm.

  Barnyard fowls do many peculiar things that foretell certain weather  conditions.

 The crow flies low and in great circles, cawing loudly,  before approaching rain.

  Sometimes the house fly is a pretty good barometer.

 Generally before a  storm they seem to light on everything, particularly persons, and we  call them "sticky.

" Generally at these times they congregate in swarms.

  Most everyone is familiar with the gnat.

 They are one of the few insects  that gives us indications and good signs, and when you see them forming  in groups and moving along in front of you, you may expect fair weather.

  There are many other interesting facts and fairy tales about indications  by animals and insects, but there is nothing scientific about them.

 It  has been demonstrated that there is nothing conclusive to be drawn from  such signs, so we will not attempt to waste pages of this book  reiterating these fables.

  Certain actions of insects and animals give indications and enable the  weather prophet to prophesy.

 The spider is a good example of an insect  prophet, and if you will observe him carefully, you will find that when  stormy weather is going to come on he shortens his webs, and if he  anticipates a long, hard storm, he not only shortens the strings that 
 hold up the web, but he strengthens them as well, and vice-versa, when  he anticipates fine weather, he lengthens his strands of the web.

 When  you see the spider cease his activities and he hangs pretty close to his  home, which is the center of the web, you will know that rain is  approaching.

 On the other hand, if he continues to spread about during a  storm, you can be pretty certain that it is not going to be of very long  duration.

  The frog is a good example of an animal prophet.

 There is a green frog  which has been studied in Germany, which will come out of the water when  rainy weather or cold is approaching.

 Some observers have placed these  frogs in a glass jar with a landing provided so that he can come out of  the water when he wants to, and he is always observed high and dry above  the water several hours in advance of a storm.

  xxx  DEFINITE CONCLUSIONS  Forecasting Weather by Means of Instruments  The first part of this book may not appeal to you, if you are of a  scientific trend of mind, but it is quite essential that you possess a  knowledge of the fundamentals treated in 
the earlier pages in order to  thoroughly understand the weather instruments we will now describe.

  These instruments are the scientific means of forecasting what the  weather is going to be.

 They definitely indicate certain things, and  from these indications you are going to be able to draw conclusions and  become a scientist or meteorologist.

 The success that you attain will  depend upon the accuracy of the instruments and the care you use in  reading them.

 You will be able to rig up a Weather Bureau of your own,  and the use of these instruments will interest anyone in a study of the  weather.

  THE WEATHER VANE  To make a forecast, it is essential from what we have already written,  to know the direction of the wind, and to determine the direction we  must have a weather vane.

 It is real important that the vane should be  sensitive to the slightest movement of the wind and give actual wind  directions.

 At the same time it must possess the property of steadiness,  so that when it is set up it will be rigid.

  Fig.

 34 shows the standard weather vane used at all United States  Weather Bureau Stations and Fig.

 35 shows the Gilbert Weather Vane.

  Fig.

 35.

 The Gilbert weather vane consists of a metal arrow pointer and  a metal rod eight inches long and five thirty-seconds of an inch in  diameter.

 The rod is fastened by means of a few staples to the side of a  pole, or whatever is to be used as a support for the vane.

 About three  inches from the top of the rod is a collar with set screw, which is  tightened, and the vane itself is then placed on the rod, the rod  passing through the small angles A and B, between the sides of the vane.

  It will be found that the vane will swing freely on this support, and by  constructing two crosspieces with letters N, S, E, and W at each end of  the pieces, of course having N pointing directly north, the vane will  swing around and show the direction
 of the wind.

  [Illustration:  Fig.

 37  ]  The standard United States Weather Bureau type hardly needs explanation,  as the illustration clearly shows all parts.

 It is the old, reliable,  standard iron, combined wind vane and anemometer support complete,  twenty feet high; iron contact box near base, improved roller bearings  for six-foot vane; latter, with electrical contacts shown enlarged at  the right.

 The vane is fastened securely to the roof of the building and  held in a perfectly vertical position.

  THE ANEMOMETER.

 Fig.

 36  It is essential to know the velocity of the wind.

 This is determined by  means of an instrument called the anemometer.

  Fig.

 36.

 The Standard U.

 S.

 Weather Bureau Station Anemometer.

  This is the well-known standard Robinson Anemometer, now in universal  use throughout the world for the registration of wind velocity, but of  the latest improved construction.

 It records electrically the miles or  kilometers, etc.

, of wind movements on a register.

 The standard pattern  as furnished to Weather Bureau stations is made of brass, highly  polished and finished, aluminum (or copper reinforced) cups, steel  spindle with hard steel bearings, a ten-mile or kilometer indicator,  electrical contacts, etc.

  [Illustration:  Fig.

 38  ]  The four hollow hemispherical cups are mounted upon cross-arms at right  angles to each other, with the open sections vertical and facing the  same way around the circumference.

 The cross-arms are on a vertical  axis, which has at its lower end an endless screw.

 This axis is  supported so as to turn with as little friction as possible.

 The endless  screw is in gear with a wheel which moves two dials registering the  number of revolutions of the cups.

 The mechanisms are mounted in a  suitable metal case with glass front, as shown in the illustration, well  protected from the weather, the whole being designed for outdoor use.

  [Illustration:  _Courtesy Julien Friez & Sons, Baltimore, Md.

_  Fig.

 39  ]  The center of the cups moves with a velocity about one-third that of the  wind which puts them in motion.

 The cups are four inches in diameter.

  The distance from center of cup to center of rotation or axis is 6.

72  inches.

 Assuming that the wind-travel is exactly three times that of the  center of the cup, the dials are marked to register miles of wind  travel, five hundred revolutions of the cups corresponding to a mile.

  The ratio of wind-travel to travel of cup is in reality variable,  depending on the velocity of the wind.

 It is less for high than low  velocities.

 It varies also with the dimensions of the instrument, being  different for every different length of arm and diameter of cup.

  On account of the great interference offered by buildings and other  obstructions to the free movement of the wind, its velocity is much less  in the vicinity of these obstructions than beyond; therefore, in  selecting the location for an anemometer, pr
eference should be given to  the more elevated points in the vicinity of the station, and some rigid  support should be used to raise the instrument as far as practicable  above the immediate influence of the office building itself.

 The support  must be set up so that the anemometer on top or on the cross-arm is as  nearly vertical as possible.

  The illustration shows clearly the appearance of an approved Weather  Bureau pattern combined support for wind instruments, similar to the one  installed at our plant.

  [Illustration:  Fig.

 40  ]  [Illustration:  _Courtesy Taylor Instrument Companies Rochester, N.

 Y.

_  Fig.

 41  ]  Fig.

 37.

 The Gilbert Anemometer.

  The Gilbert Anemometer consists of a case containing a spindle passing  through a worm gear, which turns a toothed gear.

 This gear in its rotary  motion makes a contact with a brass brush, which is connected  electrically with a flashlight.

 The cross-arms, with cups attached, is  placed on the spindle, and as the wind blows, it revolves the cups,  causing the contact.

 The velocity of the wind is determined by counting  the flashes for fifteen seconds, thus giving you the number of miles per  hour.

 For instance, if light flashes eight times in fifteen seconds,  this signifies that the wind is blowing eight miles an hour.

  Fig.

 38.

 How to Connect the Gilbert Anemometer.

  By referring to the diagram, you will see that one wire which should be  the annunciator wire, or even a small electric light wire, is connected  from the wire at the anemometer case directly to one side of the lamp  socket.

 Another piece of the same size wire connects the other side of  the lamp socket to one terminal of your switch.

 The second terminal of  the switch should be connected to an outer post of one dry battery.

 The  inner post of this same dry battery should be connected to the outer  post of the second dry battery.

 Complete the circuit by connecting the  inner post of the second dry battery to any one of the screws at the  bottom of the anemometer case.

 The lamp used should be a small  flashlight battery lamp for use on two and a half to three volts.

 Be  sure in making the connections that the ends of your wire are scraped  free from insulation and dirt.

 This can be done by cutting off the  insulation with a knife and then rubbing the copper wire bright by a  piece of sandpaper or emery cloth, or even a file.

 The switch should be  left open when you are not taking readings, in order to prolong the life  of your batteries.

 By unloosening the little screw in the hub of the  anemometer vanes, you can remove them and also take off the brass cap on  the anemometer case.

 This should be taken apart once or twice a month,  and some machine oil used around the bearings to keep them from wearing  out too quickly.

 THE STANDARD ELECTRICAL SUNSHINE RECORDER AND THE GILBERT SUNSHINE  RECORDER  Fig.

 39.

 The standard sunshine recorder is designed for recording the  duration of sunshine electrically, continuously, and automatically, on a  register.

 The instrument is essentially a differential air thermometer  in the form of a straight glass tube with cylindrical bulbs at each end,  enclosed in a protecting glass sheath, with suitable platinum wire  electrodes fused in at the center, the whole mount
ed in a metal socket  on an adjustable support.

  [Illustration:  _Courtesy Taylor Instrument Companies, Rochester, N.

 Y.

_  Fig.

 42  ]  The base is secured to the support on the roof so that the glass tube  points north and south, with the blackened bulb toward the south and  lowermost, then the tube is inclined at such an angle that the  instrument will begin and cease to record 
sunshine with the proper  degree of cloudiness.

 This inclination should be approximately 45° from  the vertical.

 The machine should be adjusted at an hour when the sun is  wholly obscured.

  In temperate and cold climates, slightly different adjustments will be  found necessary at different seasons of the year.

  Fig.

 40.

 The Gilbert Sunshine Recorder consists of a metal case,  cylindrical in form, with a piece of metal turned up on the ends,  dividing the cylinder in half.

 On each side of the case are small holes  through which the sun casts its rays and records its movement and  duration on a small piece of blue print paper inside the cylinder, one  piece of paper being in each compartment.

 When the blue print paper is  dipped in water, it becomes entirely bleached, with the exception of the  path made by the sun, which shows up in a blue line.

  [Illustration:  _Courtesy Julien Friez & Sons, Baltimore, Md.

_  Fig.

 43  ]  [Illustration:  _Courtesy Julien Friez & Sons, Baltimore, Md.

_  Fig.

 44  ]  The sunshine recorder should be set up so that the ends point directly  north and south.

 The holes pierced in the sides of the case are nearer  one end than the other.

 The end that the holes are nearest should be  toward the south.

 It should be held firmly in place.

  xxx THE BAROMETER  The barometer is used for measuring the pressure of the atmosphere.

 The  principle of this instrument was first discovered by Torricelli, a pupil  of Galileo, the great Italian philosopher and scientist, in 1643.

 Many  and various types of instruments have been made, but the two most  generally used, especially where accurate indications are desired, are  the mercurial and aneroid barometers.

 Either of these instruments are  quite sensitive to changes in the weight or pressure of the earth’s  atmosphere, and from their variations we are able to draw conclusions  relative to changes in the weather.

 Figs.

 No.

 41 and 42 illustrate the  standard mercurial and aneroid barometers used most extensively today.

 A  description of these barometers will serve to make the photographs  clearer to the readers of this text.

 THE MERCURIAL BAROMETER (Fig.

 41)  The mercurial barometer in use today is practically the same as that  invented by Torricelli.

 Of course, many changes have been made in the  case containing the tube of mercury, adding to its attractiveness, but  the principle remains the same.

  The standard mercurial barometer consists of a straight glass tube about  thirty-two or thirty-three inches in length, hermetically sealed at one  end.

 The tube is of half-inch bore and is filled with chemically pure  mercury, which has been boiled in the tube to insure the total exclusion  of all air and moisture.

 After the tube has been filled, the open end is  immersed in a cistern of mercury.

 Upon immersion the mercury drops in  the tube to a height of 29.

92 inches at sea level, or until  counterbalanced by the weight of the surrounding atmosphere pressing  upon the surface of the mercury in the cistern.

 The space in the top of  the tube is a perfect vacuum and is called the Torricellian vacuum.

  The glass mercury tube is enclosed in a brass case.

 About two inches  from the top of the case is an opening extending down the front and back  for a distance of about eight inches.

 On each side of this opening is a  graduated scale, one side being in inches and the other graduated in  centimeters.

 The opening is fitted with a sliding vernier scale  graduated in millimeters, thus permitting the reading of changes in the  height of the mercury column most accurately, as the sliding vernier may  be adjusted to the level of the mercury by means of a t
humb screw fitted  on the side of the case.

 The cistern containing the mercury is of glass,  with a soft leather or chamois bottom and an adjusting screw, used to  raise or lower the level of the mercury, so that it just comes in  contact with a small ivory point, inserted in the top of the cister
n,  and which is used to mark the zero of the scale.

 Observations of the  changes in the atmospheric pressure should be taken at regular  intervals, and it is necessary to adjust the height of the mercury in  the cistern before each observation.

 This is done by bringing the ivory  point in contact with the level of the mercury and then bringing the  vernier scale absolutely level with the top of the column of mercury in  the tube, and then take the reading.

  The mercurial barometer is a very delicate instrument and when once  placed in the desired position should not be moved.

 Care should be taken  that the room in which the barometer is placed is of nearly uniform  temperature, for if the temperature at the top of the barometer is  different than the temperature at the bottom, of course there will be an  effect produced on th
e changes in the mercury column.

 All other  barometers are set by the mercurial.

  THE ANEROID BAROMETER (Fig.

 42).

  The aneroid barometer is so constructed that it contains no liquid  whatever, and thus derives its name from the Greek compound word  "aneroid," meaning "without fluid.

"  The essential parts of the instrument are a metallic case from which the  air has been exhausted, and which contains a spring.

 The case of elastic  metal is fastened to a base plate at the bottom and to the spring at the  top.

 The pressure of the atmosphere causes the case to expand and  contract, thus affecting the spring, which is connected to a needle or  dial, causing the dial to move around on the scale on the face of the  instrument and record the changes.

 The scale is marked off in inches  from 28 to 31, and besides a brass hand or pointer, used to designate  the changes in the atmospheric pressure, there is a small index hand to  set over the needle so that the amount of change in a certain period is  ea
sily known on consulting the instrument.

  [Illustration:  _Courtesy Julien Friez & Sons, Baltimore, Md.

_  Fig.

 45  ]  The dial of the barometer is marked with the words "Fair," "Change," and  "Rain," etc.

, but these words have no significance, and should be  disregarded.

 For instance, 29½ is marked "Change"; 30, "Fair"; 31, "Very  dry"; 28½, "Rain.

" If the barometer, which has been standing at 30.

9,  suddenly drops down to 29.

9, this is positive indication that a storm is  approaching, with strong winds, yet, according to the dial on the  aneroid, the reading would be "Fair.

" If the barometer were standing at  28 and rose to 29, this would actually indicate approach of cold, dry  weather, and yet on the dial it reads "Rain.

" This simply goes to show  that the readings on the dial are of no significance whatsoever, and are  not to be relied upon.

  The aneroid is not as accurate an instrument as the mercurial, so should  be checked up occasionally with the mercurial barometer.

  [Illustration:  _Courtesy Taylor Instrument Companies Rochester, N.

 Y.

_  Fig.

 46  ]  The aneroid type of barometer is also used in altitude work, but must be  compensated before using.

  This type of barometer possesses several advantages over the mercurial  in that it is portable and therefore used for altitude work; at sea it  is used because there is no fluid to become unsettled by the motion of  the vessel; it is used also in observ
atory work because the action is  quicker than the mercurial barometer action, and sudden changes likely  to occur are indicated.

 INDICATIONS FROM THE BAROMETER  A single observation reading of the barometer is of no significance.

  Readings must be taken at different intervals or the results will be  misleading.

 The important thing about the barometer is to watch the rise  and fall, particularly, whether it is gradual or rapid.

 From no single  reading can you make an observation or a forecast.

 A rapid rise  indicates that a strong wind is apt to blow.

 A rapid fall indicates that  the weather will be unsettled, and that strong winds are apt to blow.

  Both indicate a change in the weather, depending upon many things,  particularly, however, the direction from which the wind blows.

 If an  observer stands with the wind blowing on his back, the area of low  barometric pressure will be at his left, and that of high barometric  pressure at his right.

 With low pressure in the west and high pressure  in the east, the wind will be from the south; but with low pressure in  the east and high pressure in the west, the wind will be from the north.

  The barometer rises for northerly winds, from northwest by the north to  eastward, for dry, or less wet weather, for less wind, or for more than  one of these changes-except on a few occasions, when rain, hail, or snow  comes from the northward with str
ong wind.

 The barometer falls for  southerly wind, from southeast, by the south, to the westward, for wet  weather, for stronger wind, or for more than one of these changes,  except on a few occasions, when moderate wind with rain or snow comes  from the northward
.

 RELATIVE HUMIDITY TABLES  _Per Cent Fahrenheit Temperatures_  Difference in Degrees Between Wet and Dry Bulb Thermometers --------------------------------------------------------------------------------- Read-¦1.

0¦2.

0¦3.

0¦4.

0¦5.

0¦6.

0¦7.

0¦8.

0¦9.

0¦10.

0¦11.

0¦12.

0¦13.

0¦14.

0¦15.

0¦16.

0¦17.

0  ing ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  of  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  Dry ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦ Bulb ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦ Ther-¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦ mom- ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ 
¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦ eter ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦ -----+---+---+---+---+---+---+---+---+---+----+----+----+----+----+----+----+----  32¦ 90¦ 79¦ 69¦ 60¦ 50¦ 41¦ 31¦ 22¦ 13¦ 4¦  ¦  ¦  ¦  ¦  ¦  ¦  33¦ 90¦ 80¦ 71¦ 61¦ 52¦ 42¦ 33¦ 24¦ 16¦ 7
¦  ¦  ¦  ¦  ¦  ¦  ¦  34¦ 90¦ 81¦ 72¦ 62¦ 53¦ 44¦ 35¦ 27¦ 18¦ 9¦ 1¦  ¦  ¦  ¦  ¦  ¦  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  35¦ 91¦ 82¦ 73¦ 64¦ 55¦ 46¦ 37¦ 29¦ 20¦  12¦ 4¦  ¦  ¦  ¦  ¦  ¦  36¦ 91¦ 82¦ 73¦ 65¦ 56¦ 48¦ 39¦ 31¦ 23¦  14¦ 6¦  ¦  ¦  ¦  ¦  ¦  37
¦ 91¦ 83¦ 74¦ 66¦ 58¦ 49¦ 41¦ 33¦ 25¦  17¦ 9¦ 1¦  ¦  ¦  ¦  ¦  38¦ 91¦ 83¦ 75¦ 67¦ 59¦ 51¦ 43¦ 35¦ 27¦  19¦  12¦ 4¦  ¦  ¦  ¦  ¦  39¦ 92¦ 84¦ 76¦ 68¦ 60¦ 52¦ 44¦ 37¦ 29¦  21¦  14¦ 7¦  ¦  ¦  ¦  ¦  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  40¦ 92¦ 84¦ 76¦ 68¦
 61¦ 53¦ 46¦ 38¦ 31¦  23¦  16¦ 9¦ 2¦  ¦  ¦  ¦  41¦ 92¦ 84¦ 77¦ 69¦ 62¦ 54¦ 47¦ 40¦ 33¦  26¦  18¦  11¦ 5¦  ¦  ¦  ¦  42¦ 92¦ 85¦ 77¦ 70¦ 62¦ 55¦ 48¦ 41¦ 34¦  28¦  21¦  14¦ 7¦  ¦  ¦  ¦  43¦ 92¦ 85¦ 78¦ 70¦ 63¦ 56¦ 49¦ 43¦ 36¦  29¦  23¦  16¦ 9¦ 3¦  ¦  ¦  44¦ 
93¦ 85¦ 78¦ 71¦ 64¦ 57¦ 51¦ 44¦ 37¦  31¦  24¦  18¦  12¦ 5¦  ¦  ¦  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  45¦ 93¦ 86¦ 79¦ 71¦ 65¦ 58¦ 52¦ 45¦ 39¦  33¦  26¦  20¦  14¦ 8¦ 2¦  ¦  46¦ 93¦ 86¦ 79¦ 72¦ 65¦ 59¦ 53¦ 46¦ 40¦  34¦  28¦  22¦  16¦  10¦ 4¦  ¦  47¦ 9
3¦ 86¦ 79¦ 73¦ 66¦ 60¦ 54¦ 47¦ 41¦  35¦  29¦  23¦  17¦  12¦ 6¦ 1¦  48¦ 93¦ 87¦ 80¦ 73¦ 67¦ 60¦ 54¦ 48¦ 42¦  36¦  31¦  25¦  19¦  14¦ 8¦ 3¦  49¦ 93¦ 87¦ 80¦ 74¦ 67¦ 61¦ 55¦ 49¦ 43¦  37¦  32¦  26¦  21¦  15¦  10¦ 5¦  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  
50¦ 93¦ 87¦ 81¦ 74¦ 68¦ 62¦ 56¦ 50¦ 44¦  39¦  33¦  28¦  22¦  17¦  12¦ 7¦ 2  51¦ 94¦ 87¦ 81¦ 75¦ 69¦ 63¦ 57¦ 51¦ 45¦  40¦  35¦  29¦  24¦  19¦  14¦ 9¦ 4  52¦ 94¦ 88¦ 81¦ 75¦ 69¦ 63¦ 58¦ 52¦ 46¦  41¦  36¦  30¦  25¦  20¦  15¦  10¦ 6  53¦ 94¦ 88¦ 82¦ 75¦ 70¦ 6
4¦ 58¦ 53¦ 47¦  42¦  37¦  32¦  27¦  22¦  17¦  12¦ 7  54¦ 94¦ 88¦ 82¦ 76¦ 70¦ 65¦ 59¦ 54¦ 48¦  43¦  38¦  33¦  28¦  23¦  18¦  14¦ 9  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  55¦ 94¦ 88¦ 82¦ 76¦ 71¦ 65¦ 60¦ 55¦ 49¦  44¦  39¦  34¦  29¦  25¦  20¦  15¦  11  56
¦ 94¦ 88¦ 82¦ 77¦ 71¦ 66¦ 61¦ 55¦ 50¦  45¦  40¦  35¦  31¦  26¦  21¦  17¦  12  57¦ 94¦ 88¦ 83¦ 77¦ 72¦ 66¦ 61¦ 56¦ 51¦  46¦  41¦  36¦  32¦  27¦  23¦  18¦  14  58¦ 94¦ 89¦ 83¦ 77¦ 72¦ 67¦ 62¦ 57¦ 52¦  47¦  42¦  38¦  33¦  28¦  24¦  20¦  15  59¦ 94¦ 89¦ 83¦ 7
8¦ 73¦ 68¦ 63¦ 58¦ 53¦  48¦  43¦  39¦  34¦  30¦  25¦  21¦  17  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  60¦ 94¦ 89¦ 84¦ 78¦ 73¦ 68¦ 63¦ 58¦ 53¦  49¦  44¦  40¦  35¦  31¦  27¦  22¦  18  61¦ 94¦ 89¦ 84¦ 79¦ 74¦ 68¦ 64¦ 59¦ 54¦  50¦  45¦  40¦  36¦  32¦  28¦ 
 24¦  20  62¦ 94¦ 89¦ 84¦ 79¦ 74¦ 69¦ 64¦ 60¦ 55¦  50¦  46¦  41¦  37¦  33¦  29¦  25¦  21  63¦ 95¦ 90¦ 84¦ 79¦ 74¦ 70¦ 65¦ 60¦ 56¦  51¦  47¦  42¦  38¦  34¦  30¦  26¦  22  64¦ 95¦ 90¦ 85¦ 79¦ 75¦ 70¦ 66¦ 61¦ 56¦  52¦  48¦  43¦  39¦  35¦  31¦  27¦  23  ¦ ¦ ¦
 ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  65¦ 95¦ 90¦ 85¦ 80¦ 75¦ 70¦ 66¦ 62¦ 57¦  53¦  48¦  44¦  40¦  36¦  32¦  28¦  25  66¦ 95¦ 90¦ 85¦ 80¦ 76¦ 71¦ 66¦ 62¦ 58¦  53¦  49¦  45¦  41¦  37¦  33¦  29¦  26  67¦ 95¦ 90¦ 85¦ 80¦ 76¦ 71¦ 67¦ 62¦ 58¦  54¦  50¦  46¦  42
¦  38¦  34¦  30¦  27  68¦ 95¦ 90¦ 85¦ 81¦ 76¦ 72¦ 67¦ 63¦ 59¦  55¦  51¦  47¦  43¦  39¦  35¦  31¦  28  69¦ 95¦ 90¦ 86¦ 81¦ 77¦ 72¦ 68¦ 64¦ 59¦  55¦  51¦  47¦  44¦  40¦  36¦  32¦  29  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  70¦ 95¦ 90¦ 86¦ 81¦ 77¦ 72¦ 68¦
 64¦ 60¦  56¦  52¦  48¦  44¦  40¦  37¦  33¦  30  71¦ 95¦ 90¦ 86¦ 82¦ 77¦ 73¦ 69¦ 64¦ 60¦  56¦  53¦  49¦  45¦  41¦  38¦  34¦  31  72¦ 95¦ 91¦ 86¦ 82¦ 78¦ 73¦ 69¦ 65¦ 61¦  57¦  53¦  49¦  46¦  42¦  39¦  35¦  32  73¦ 95¦ 91¦ 86¦ 82¦ 78¦ 73¦ 69¦ 65¦ 61¦  58¦  
54¦  50¦  46¦  43¦  40¦  36¦  33  74¦ 95¦ 91¦ 86¦ 82¦ 78¦ 74¦ 70¦ 66¦ 62¦  58¦  54¦  51¦  47¦  44¦  40¦  37¦  34  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  75¦ 96¦ 91¦ 87¦ 82¦ 78¦ 74¦ 70¦ 66¦ 63¦  59¦  55¦  51¦  48¦  44¦  41¦  38¦  34  76¦ 96¦ 91¦ 87¦ 83¦
 78¦ 74¦ 70¦ 67¦ 63¦  59¦  55¦  52¦  48¦  45¦  42¦  38¦  35  77¦ 96¦ 91¦ 87¦ 83¦ 79¦ 75¦ 71¦ 67¦ 63¦  60¦  56¦  52¦  49¦  46¦  42¦  39¦  36  78¦ 96¦ 91¦ 87¦ 83¦ 79¦ 75¦ 71¦ 67¦ 64¦  60¦  57¦  53¦  50¦  46¦  43¦  40¦  37  79¦ 96¦ 91¦ 87¦ 83¦ 79¦ 75¦ 71¦ 68
¦ 64¦  60¦  57¦  54¦  50¦  47¦  44¦  41¦  37  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦  80¦ 96¦ 91¦ 87¦ 83¦ 79¦ 76¦ 72¦ 68¦ 64¦  61¦  57¦  54¦  51¦  47¦  44¦  41¦  38  82¦ 96¦ 92¦ 88¦ 84¦ 80¦ 76¦ 72¦ 69¦ 65¦  62¦  58¦  55¦  52¦  49¦  46¦  43¦  40  84¦ 96¦
 92¦ 88¦ 84¦ 80¦ 77¦ 73¦ 70¦ 66¦  63¦  59¦  56¦  53¦  50¦  47¦  44¦  41  86¦ 96¦ 92¦ 88¦ 85¦ 81¦ 77¦ 74¦ 70¦ 67¦  63¦  60¦  57¦  54¦  51¦  48¦  45¦  42  88¦ 96¦ 92¦ 88¦ 85¦ 81¦ 78¦ 74¦ 71¦ 67¦  64¦  61¦  58¦  55¦  52¦  49¦  46¦  43  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦
  ¦  ¦  ¦  ¦  ¦  ¦  90¦ 96¦ 92¦ 89¦ 85¦ 81¦ 78¦ 75¦ 71¦ 68¦  65¦  62¦  59¦  56¦  53¦  50¦  47¦  44  92¦ 96¦ 92¦ 89¦ 85¦ 82¦ 78¦ 75¦ 72¦ 69¦  65¦  62¦  59¦  57¦  54¦  51¦  48¦  45  94¦ 96¦ 93¦ 89¦ 86¦ 82¦ 79¦ 75¦ 72¦ 69¦  66¦  63¦  60¦  57¦  54¦  52¦  49¦ 
 46  96¦ 96¦ 93¦ 89¦ 86¦ 82¦ 79¦ 76¦ 73¦ 70¦  67¦  64¦  61¦  58¦  55¦  53¦  50¦  47  98¦ 96¦ 93¦ 89¦ 86¦ 83¦ 79¦ 76¦ 73¦ 70¦  67¦  64¦  61¦  59¦  56¦  53¦  51¦  48  ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦ ¦  ¦  ¦  ¦  ¦  ¦  ¦  ¦ 100¦ 96¦ 93¦ 90¦ 86¦ 83¦ 80¦ 77¦ 74¦ 71¦  68¦  65
¦  62¦  59¦  57¦  54¦  52¦  49 ---------------------------------------------------------------------------------  [Illustration:  _Courtesy Taylor Instrument Companies, Rochester, N.

Y.

_  Fig.

 47  Like the hygrometer, this instrument measures the "relative humidity.

"  ]  [Illustration:  Fig.

 48  GILBERT HYGROMETER  ] GENERAL BAROMETER INDICATIONS  A gradual but steady rise indicates settled fair weather.

  A gradual but steady fall indicates unsettled or wet weather.

  A very slow rise from a low point is usually associated with high winds  and dry weather.

  A rapid rise indicates clear weather with high winds.

  A very slow fall from a high point is usually connected with wet and  unpleasant weather without much wind.

  The following table of the United States Weather Bureau gives a summary  of the wind and barometer indications: Barometer Reduced to Sea Level Wind  Character of Weather Indicated  Direction --------------------------------------------------------------
--------- 30.

10 to 30.

20 and steady  SW to NW  Fair with slight temperature  xxx  changes for 1 to 2 days 30.

10 to 30.

20 and rising  SW to NW  Fair, followed within 2 days rapidly  by warmer and rain 30.

10 to 30.

20 and falling SW to NW  Warmer, with rain in 24 to 36 slowly  xxx hours 30.

10 to 30.

20 and falling SW to NW  Warmer, with rain in 18 to 24 rapidly  hours 30.

20 and above and stationary SW to NW  Continued fair, with no  xxx  decided temperature change 30.

20 and above and falling  SW to NW  Slowly rising temperature and slowly  xxx fair for two days 30.

10 to 30.

20 and falling S to SE Rain within 24 hours slowly 30.

10 to 30.

20 and falling S to SE Wind increasing in force, with rapidly  rain within 12 to 24 hours 30.

10 to 30.

20 and falling SE to NE  Rain in 12 to 18 hours slowly 30.

10 to 30.

20 and falling SE to NE  Increasing wind, with rain rapidly  within 12 hours 30.

10 and above and falling  E to NE In summer, with light winds, slowly  xxx rain may not fall for  xxx  several days.

 In winter,  xxx  rain within 24 hours 30.

10 and above and falling  E to NE In summer, rain probably rapidly  within 12 to 24 hours.

 In  xxx  winter, rain or snow, with  xxx  increasing wind will often  xxx  set in, when the barometer  xxx  begins to fall and the wind  xxx  sets in from the NE 30 or below and falling slowly SE to NE  Rain will continue 1 or 2 days 30 or below and fall
ing  SE to NE  Rain, with high wind, followed rapidly  within 24 hours by clearing  xxx  and cooler 30 or below and rising slowly  S to SW Clearing within a few hours  xxx  and continued fair for  xxx  several days 29.

80 or below and falling S to E  Severe storm of wind and rain rapidly  or snow imminent, followed  xxx  within 24 hours by clearing  xxx  and colder 29.

80 or below and falling E to N  Severe northeast gales and rapidly  heavy rain or snow, followed  xxx  in winter by a cold wave 29.

80 or below and rising  Going to  Clearing and colder rapidly  W  A sudden fall indicates a sudden shower or high winds, or both.

  [Illustration:  _Courtesy Julien Friez & Son Baltimore, Md.

_  Fig.

 49  U.

 S.

 STANDARD RAIN GAUGE  ]  A stationary barometer indicates a continuance of existing weather  conditions.

 (_Note_: Tap the barometer slightly on the face.

 If the  hands move a trifle, it indicates that there is the tendency to rise or  fall, depending upon the direction of movement of the hands.

)  Northeasterly winds precede storms that approach from the southwest;  that is, in New England and the Middle States and the Ohio Valley.

  Southeasterly winds precede storms that approach from the Lake region.

  xxx  THERMOMETERS  For information regarding the manufacture of thermometers, we recommend  P.

 R.

 Jameson’s book, "Weather and Weather Instruments," published by  the Taylor Instrument Companies of Rochester, N.

 Y.

  Thermometers are of great importance to us in determining weather.

  LOCATION OF THERMOMETERS  1.

 They must be properly exposed.

  2.

 A good circulation of air around them is necessary.

  3.

 They must be properly protected from the rays of the sun.

  _Note_: If these instructions are not carefully followed out, errors are  apt to occur, and you will be misled.

  For a change of wind towards northerly directions, a thermometer falls.

  For a change of wind toward southerly directions a thermometer rises.

  [Illustration:  Fig.

 50  GILBERT RAIN GAUGE  ]  MAXIMUM AND MINIMUM THERMOMETERS  Maximum and minimum thermometers are used to record the daily maximum  and minimum temperatures.

 Fig.

 46 shows a typical maximum and minimum  thermometer used for giving the extremes of temperature.

 One side of the  thermometer has a scale reading, beginning at the top, from 60° below  zero to 140° above zero.

 This is the scale used when determining the  coldest temperature reached during a day.

 The other side of the  thermometer has a scale marked from 70° below zero, beginning at the  bottom and reading up, to 130° above zero.

 On this side the maximum heat  reached during the day is recorded.

 There is a small metal piece in the  tubes, one on each side, and as the mercury pushes ahead or recedes, the  small index is left at the lowest point reached in one tube and at the  highest point reached in the other.

 The small metal piece is drawn back  to the level of the mercury by means of a small magnet.

  WHEN MAXIMUM TEMPERATURE IS REACHED  You can generally look for maximum temperature between three and four  o’clock in the afternoon.

 At this time the sun has reached its highest  altitude.

  [Illustration:  _Courtesy Julien Friez & Sons, Baltimore, Md.

_  Fig.

 51  TIPPING BUCKET RAIN GAUGE  ]  WHEN THE MINIMUM TEMPERATURE IS REACHED  This usually occurs a little while before sunrise.

 It is important in  weather observing to make a record of the highest temperature of the day  and the lowest temperature of the night.

 Continuous observation, as the  reader will appreciate, is practically impossible for such a record.

  THE THERMOMETER FOR HUMIDITY IN THE AIR  Moisture or dampness in the air, as shown by an instrument called the  hygrometer, increases before rain, fog, or dew.

  Before describing the hygrometer, a definition of a few of the terms  used in conjunction with the instrument will be found useful.

 ABSOLUTE HUMIDITY  The amount of vapor actually present in the atmosphere is termed the  absolute humidity, expressed usually either in the expansive force that  the vapor exerts or in its weight in grains per cubic foot of air.

 RELATIVE HUMIDITY  The absolute humidity divided by the amount of vapor that might exist if  the air were saturated gives a ratio that is called the relative  humidity.

  xxx DEW POINT  The temperature at which moisture begins to be condensed on a cold  vessel or other container and becomes visible is called the dew point.

  HOW HYGROMETERS ARE MADE  The most generally used hygrometer consists of two ordinary  thermometers, the bulb of one being covered with a piece of muslin and  kept constantly moistened with water by means of a wick or cotton thread  communicating with a
 container of water.

 The difference in the readings  of the two thermometers, the wet and the dry, is observed, and knowing  this, it is very easy to determine the humidity by consulting a table  (see table on pages 58-59), which has been prepared for this purpose.

  These instruments are, according to the increase in price, equipped with  a table, and the container is held in a wire frame, as you will see from  the Figs.

 49-50 showing the standard Weather Bureau station instrument  and the Gilbert hygrometer.

  Fig.

 49 shows the U.

 S.

 Standard Weather Bureau Station Rain Gauge, Fig.

  50 the Gilbert Rain Gauge and Fig.

 51 the U.

 S.

 Standard Weather Bureau  Station Rain Gauge, Tipping Bucket Type.

  The Gilbert Weather Station is equipped with the Tipping Bucket Type  Rain Gauge.

 Fig.

 51 shows the apparatus clearly, complete and mounted  ready for use.

 The brass bucket seen in position through the open door  is adjusted to tip for each hundredth inch of rainfall collected in the  twelve-inch diameter receiver at the top, and this rainfall is  electrically recorded at any convenient distance on a regist
er.

 After  any desired period the water may be drawn off and check measurements  made by means of the brass measuring tube and graduated cedar stick  shown in the figure.

 THE GILBERT RAIN GAUGE (Fig.

 50).

 (_a_) Tube.

 (_b_) Funnel.

 (_c_) Measuring stick.

  The essential parts of the Gilbert Rain Gauge consists of a metal tube  twelve inches long, having a diameter of 15/16 inches (inside) and a  funnel-shaped top, the neck of which fits snugly into the open end of  the metal tube.

 The outside diameter of the neck of the funnel is a  trifle less than 15/16 inches.

 The area of the circle formed at the top  of the tube is one-tenth the area of the funnel circle.

 A measuring  stick is provided to measure the rainfall collected in the tube.

  To determine the amount of rainfall on the surface of the ground, the  rain collected in the tube should be measured at regular intervals,  usually twelve hours apart.

 For every inch of rain collected in the  tube, as denoted by the measuring stick, it means that there is one  one-tenth of an inch of rain on the ground; if 10 inches of rain in the  tube, it signifies one inch of rain on the ground.

 In other words,  divide the figure recorded on the measuring stick by ten for actual  rainfall.

  It is well to put some sort of a shelter around the gauge, so that it  will be protected from strong winds.

 The shelter is usually placed at a  distance from the tube equal to the height of the tube.

 With the Gilbert  rain gauge it is well to erect the shelter at a distance of about three  feet from the tube.

 It is essential that the gauge be held in an upright  position, so it should be fastened to the roof.

  Snow is measured by melting the quantity collected in the gauge and  follow the same procedure as in rainfall measurements.

  There is another very common method, called ground measurement.

 There  are many instances where ground measurements are inaccurate:  1.

 When snow and rain are mixed or alternate.

  2.

 When melting accompanies snowfall.

  3.

 When snow is already upon the ground.

  4.

 When the amount of fall is very small.

  5.

 When drifting is very bad.

  6.

 When the snow is blown about after the storm and before measurements  have been made.

  A bucket and a spring balance are used.

 The bucket is filled with snow,  but not packed down too hard, and weighed.

 The reading of the index hand  on the spring balance gives the density of the snow.

 The depth of the  snow in the vicinity of the spot from which the bucket was filled is  obtained and this figure is multiplied by the density, thus giving the  water equivalent of the snow collected.

 For instance, if the reading of  the balance was .

16, and the depth of the snow was 7 inches, multiply  .

16 by 7, and the result, 1.

12, is the water equivalent of the snow.

 THERMOMETER SCALES  The first thermometer scale to give satisfaction was devised in 1714 by  Fahrenheit.

 He determined the fixed points on the thermometer in a very  novel manner.

 Having been born at Dantzig, he took for the zero point on  his scale the lowest temperature observed by him at Dantzig, which he  found was that produced by mixing equal quantities of snow and  sal-ammoniac.

 The space between this point and that to which the mercury  rose at the temperature of boiling water he divided into 212 parts.

 He  determined, with his thermometer, that the atmospheric pressure governed  the boiling point of water.

 Today the Fahrenheit thermometer is used  extensively, and has for its freezing point 32° and for its boiling  point 212°.

  Another scale that has not become too well known, because of the fact  that it did not meet with public favor, was devised by a Frenchman,  named Reaumur, in 1730, and bears his name.

 He determined the freezing  point of the scale at 0° and the boiling point of water at 80°.

  Another Frenchman, named Anders Celsius, devised a scale with the  boiling point of water at 0° and the freezing point at 100°.

 In 1743 a  Frenchman, named Christin, living at Lyons, France, reversed the points,  and today the scale is known as the Centigrade scale, and, together with  the Fahrenheit scale, is used almost exclusively wherever thermometers  are required.

  HOW TO CHANGE ONE SCALE INTO ANOTHER  Centigrade degrees into Fahrenheit: multiply by 9, divide the product by  5 and add 32.

  Fahrenheit degrees into Centigrade: subtract 32, multiply by 5, and  divide by 9.

  Reaumur degrees into Fahrenheit: multiply by 9, divide by 4, and add 32.

  Fahrenheit degrees into Reaumur: subtract 32, multiply by 4, and divide  by 9.

  Reaumur degrees into Centigrade: multiply by 5 and divide by 4.

  Centigrade degrees into Reaumur: multiply by 4 and divide by 5.

  WEATHER BUREAU STATIONS OF THE UNITED STATES AND WEATHER BUREAU MAPS  The following is a list of the Weather Bureau Stations of the United  States, and from any of these offices, preferably the one nearest you,  you will be able to obtain the 
weather reports and weather map (see Fig.

  52), indicating many things of interest, and from which you will be able  to make a careful study of the weather.

 ABILENE, TEX.

 ALBANY, N.

 Y.

 ALPENA, MICH.

 AMARILLO, TEX.

 ANNISTON, ALA.

 ASHEVILLE, N.

 C.

 ATLANTA, GA.

 ATLANTIC CITY, N.

 J.

 AUGUSTA, GA.

 BAKER, ORE.

 BALTIMORE, MD.

 BENTONVILLE, ARK.

 BINGHAMTON, N.

 Y.

 BIRMINGHAM, ALA.

 BISMARCK, N.

 D.

 BLOCK ISLAND, R.

 I.

 BOISE, IDA.

 BOSTON, MASS.

 BROKEN ARROW, OKLA.

 BUFFALO, N.

 Y.

 BURLINGTON, VT.

 CAIRO, ILL.

 CANTON, N.

 Y.

 CAPE HENRY, VA.

 CAPE MAY, N.

 J.

 CHARLES CITY, IA.

 CHARLESTON, S.

 C.

 CHARLOTTE, N.

 C.

 CHATTANOOGA, TENN.

 CHEYENNE, WYO.

 CHICAGO, ILL.

 CINCINNATI, OHIO CLALLAM BAY, WASH.

 CLEVELAND, OHIO COLUMBIA, MO.

 COLUMBIA, S.

 C.

 COLUMBUS, OHIO CONCORD, N.

 H.

 CONCORDIA, KANS.

 CORPUS CHRISTI, TEX.

 DALLAS, TEX.

 DAVENPORT, IA.

 DAYTON, OHIO DEL RIO, TEX.

 DENVER, COLO.

 DES MOINES, IA.

 DETROIT, MICH.

 DEVILS LAKE, NO.

 DAK.

 DODGE CITY, KANS.

 DREXEL, NEB.

 DUBUQUE, IA.

 DULUTH, MINN.

 EASTPORT, ME.

 ELKINS, W.

 VA.

 ELLENDALE, NO.

 DAK.

 EL PASO, TEX.

 ERIE, PA.

 ESCANABA, MICH.

 EUREKA, CAL.

 EVANSVILLE, IND.

 FORT SMITH, ARK.

 FORT WAYNE, IND.

 FORT WORTH, TEX.

 FRESNO, CAL.

 GALVESTON, TEX.

 GRAND HAVEN, MICH.

 GRAND JUNCTION, COLO.

 GRAND RAPIDS, MICH.

 GREEN BAY, WIS.

 GREENVILLE, S.

 C.

 GROESBECK, TEX.

 HANNIBAL, MO.

 HARRISBURG, PA.

 HARTFORD, CONN.

 HATTERAS, N.

 C.

 HAVRE, MONT.

 HELENA, MONT.

 HONOLULU, HAWAII HOUGHTON, MICH.

 HOUSTON, TEX.

 HURON, SO.

 DAK.

 INDEPENDENCE, CAL.

 INDIANAPOLIS, IND.

 IOLA, KANS.

 ITHACA, N.

 Y.

 JACKSONVILLE, FLA.

 JUNEAU, ALASKA KALISPELL, MONT.

 KANSAS CITY, MO.

 KEOKUK, IOWA KEY WEST, FLA.

 KILAUEA, HAWAII KNOXVILLE, TENN.

 LA CROSSE, WIS.

 LANDER, WYO.

 LANSING, MICH.

 LEESBURG, GA.

 LEWISTON, IDAHO LEXINGTON, KY.

 LINCOLN, NEB.

 LITTLE ROCK, ARK.

 LOS ANGELES, CAL.

 LOUISVILLE, KY.

 LUDINGTON, MICH.

 LYNCHBURG, VA.

 MACON, GA.

 MADISON, WIS.

 MANTEO, N.

 C.

 MARQUETTE, MICH.

 MEMPHIS, TENN.

 MERIDIAN, MISS.

 MIAMI, FLA.

 MILWAUKEE, WIS.

 MINNEAPOLIS, MINN.

 MOBILE, ALA.

 MODENA, UTAH MONTGOMERY, ALA.

 MOUNT TAMALPAIS, CAL.

 NANTUCKET, MASS.

 NASHVILLE, TENN.

 NEAH BAY, WASH.

 NEW HAVEN, CONN.

 NEW ORLEANS, LA.

 NEW YORK, N.

 Y.

 NORFOLK, VA.

 NORTHFIELD, VT.

 NORTH HEAD, WASH.

 NORTH PLATTE, NEB.

 OKLAHOMA, OKLA.

 OMAHA, NEB.

 OSWEGO, N.

 Y.

 PALESTINE, TEX.

 PARKERSBURG, W.

 VA.

 PENSACOLA, FLA.

 PEORIA, ILL.

 PHILADELPHIA, PA.

 PHOENIX, ARIZ.

 PIERRE, SO.

 DAK.

 PITTSBURGH, PA.

 POCATELLO, IDAHO POINT REYES LIGHT, CAL.

 PORT ANGELES, WASH.

 PORT ARTHUR, TEX.

 PORT HURON, MICH.

 PORTLAND, ME.

 PORTLAND, ORE.

 PROVIDENCE, R.

 I.

 PUEBLO, COLO.

 RALEIGH, N.

 C.

 RAPID CITY, SO.

 DAK.

 READING, PA.

 RED BLUFF, CAL.

 RENO, NEV.

 RICHMOND, VA.

 ROCHESTER, N.

 Y.

 ROSEBURG, ORE.

 ROSWELL, NEW MEX.

 ROYAL CENTER, IND.

 SACRAMENTO, CAL.

 SAGINAW, MICH.

 ST.

 JOSEPH, MO.

 ST.

 LOUIS, MO.

 ST.

 PAUL, MINN.

 SALT LAKE CITY, UTAH SAN ANTONIO, TEX.

 SAN DIEGO, CAL.

 SAND KEY, FLA.

 SANDUSKY, OHIO SANDY HOOK, N.

 J.

 SAN FRANCISCO, CAL.

 SAN JOSE, CAL.

 SAN JUAN, PORTO RICO SAN LUIS OBISPO, CAL.

 SANTA FE, NEW MEX.

 SAULT SAINTE MARIE, MICH.

 SAVANNAH, GA.

 SCRANTON, PA.

 SEATTLE, WASH.

 SEKIOU, WASH.

 SHERIDAN, WYO.

 SHREVEPORT, LA.

 SIOUX CITY, IOWA SPOKANE, WASH.

 SPRINGFIELD, ILL.

 SPRINGFIELD, MO.

 SYRACUSE, N.

 Y.

 TACOMA, WASH.

 TAMPA, FLA.

 TATOOSH ISLAND, WASH.

 TAYLOR, TEX.

 TERRE HAUTE, IND.

 THOMASVILLE, GA.

 TOLEDO, OHIO TONOPAH, NEV.

 TOPEKA, KANS.

 TRENTON, N.

 J.

 TWIN, WASH.

 VALENTINE, NEB.

 VICKSBURG, MISS.

 WAGON WHEEL GAP, COLO.

 WALLA WALLA, WASH.

 WICHITA, KANS.

 WILLISTON, NO.

 DAK.

 WILMINGTON, N.

 C.

 WINNEMUCCA, NEV.

 WYTHEVILLE, VA.

 YANKTON, SO.

 DAK.

 YELLOWSTONE PARK, WYO.

 YUMA, ARIZ.

  You will notice that on this map different lines are drawn: First, the  Isobar lines-these are solid lines drawn through places which have the  same barometric pressure.

 Second, the Isotherm lines-these are dotted  lines drawn through places having the same temperature.

  The Weather Bureau Maps are gotten out on the same day all over the  country, and the preparation of them is quite interesting.

  At 7:40 A.

 M.

 simultaneous readings are taken at all weather bureau  stations of the country.

 On the coast, where the time is three hours  different than at New York, the readings are taken at 4:40, so that the  hour corresponds at all places.

 At 8:00 A.

 M.

 the various stations  telephone their findings to the Western Union Office located in their  city and immediately the messages are transmitted by Western Union to a  central district office, or circuit center as it is called.

 For New  England, the circuit center is Boston.

 All messages are received at this  office, and from here transmitted to the next office, which is New York,  and from New York to the next center, until the news is transmitted to  the coast.

 The wires are open from 8:00 until 9:30 A.

 M.

 The western  offices follow the same procedure until the weather indications are  received by all stations.

 Immediately the preparation of the map is  begun and they are mailed to interested parties by the Weather Bureau  Stations of the United States.

  Figs.

 52, 53 and 54 show three maps, typifying storms traveling from the  west to the east, and by studying them on successive days you can at  once grasp the importance of studying the weather from these maps.

  Fig.

 53 shows a storm of low pressure and how this area of low pressure  is progressing and moving from the west to the east.

 Particular notice  should be taken of how fast the storm travels, that is, the distance it  goes each day, and the direction it is going and the results.

  [Illustration:  Fig.

 52  ]  [Illustration:  Fig.

 53  ]  [Illustration:  Fig.

 54  ]  The arrows denote the direction of the wind, and you will notice they  point to the region of low barometric pressure.

 In the regions of high  barometric pressure the winds are in the opposite direction.

 This  readily explains to you why it is that you can expect changes in weather  conditions when the wind changes.

  From the markings and printed matter on each map, information is secured  regarding observations of the barometer, thermometer, wind velocity,  direction of the wind, kind of clouds, and their movements, and the  amount of precipitation (rain or snow), 
in different localities.

 HOW THE STATE OF THE WEATHER IS INDICATED  Clear, partly cloudy, cloudy, rain or snow indications are symbolized.

  The shaded area designates places or areas where precipitation has  occurred during the preceding twelve hours.

 WHAT THE WORDS "HIGH" OR "LOW" MEAN ON THE MAP  Low barometric pressure, or the storm centers, are indicated on the map  by the word "low.

" High barometric pressure centers are indicated by the  word "high.

" Note how they move in an easterly direction; how they are  progressive.

 They can be compared to a series of waves, which we will  call atmospheric waves.

 The crest of the wave may be likened to the  "highs" and the troughs to the "lows.

"  Usually the winds are southerly or easterly and therefore warmer in  advance of a "low.

" When the "lows" progress east of a place, the wind  generally shifts to westerly and the temperature lowers.

 The westward  advance of the "lows" is preceded by precipitation, and almost always in  the form of rain or snow, following which the weather is generally  clear.

 Note how a "low" is followed by a "high," and so on as they move  along eastwardly.

  WHAT ISOTHERMS INDICATE  If the Isotherms run nearly parallel, that is, east and west, there will  most likely be no change in the temperature.

 Southerly to east winds  prevail west of the nearly north and south line, passing through the  middle of a "high" and also east of a like line passing through the  middle of a "low.

"  To the west of a nearly north and south line passing through the middle  of a "low," northerly to westerly winds prevail.

 We will find the same  condition prevailing to the east of a line passing through the center of  a "high.

"  [Illustration:  Fig.

 55  ]  When we find an absence of decidedly energetic "lows" and "highs," this  is an indication of the continuance of existing weather.

 We can expect  this state of the atmosphere until later maps show a beginning of a  change, usually first appearing in the west.

 TRACKS OF STORMS IN THE UNITED STATES  The storms of the United States follow, however, year after year, a  series of tracks, not likely to change suddenly, and not irregular, but  related to each other by very well-defined laws.

  The United States Weather Bureau has made a very intensive study of the  positions of the tracks of the storms.

 Fig.

 55 shows the mean tracks and  the movement of storms from day to day.

 This map indicates that  generally there are two sets of lines running west and east, one set  over the northwestern boundary, the Lake region, and the St.

 Lawrence  Valley, the other set over the middle Rocky Mountain districts and the  Gulf States.

 Each of these is double, with one for the "highs" and one  for the "lows.

" Furthermore, there are lines crossing from the main  tracks to join them together, showing how storms pass from one to the  other.

 On the chart, the heavy lines all belong to the tracks of the  "highs," and the lighter lines to the track of the "lows.

" THE MODE OF TRAVEL OF THE "HIGHS"  A "high" reaching the California coast may cross the mountains near Salt  Lake City (follow the track on the map), and then pass directly over the  belt of the Gulf States, turning northeastward and reaching the Virgin
ia  coast; or it may move farther northward, cross the Rocky Mountains in  the State of Washington, up the Columbia River Valley, then turn east,  and finally reach the Gulf of St.

 Lawrence.

 These tracks are located  where they are by the laws of general circulation of the atmosphere and  the outline of the North American continent.

 This movement of the  "highs" from the middle Pacific coast to Florida or to the Gulf of St.

  Lawrence is confined to the summer half of the year, that is, from April  to September.

 In the winter months, on the other hand, the source of the  "highs" is different, though they reach the same terminals.

  xxx  HISTORICAL FACTS  xxx  THERMOMETERS  Galileo discovered the principles of the thermometer in 1592.

 The Grand  Duke of Tuscany, Ferdinand II, is given credit for perfecting it in  1610.

 Athanasius Kircher is given credit for the discovery of the  mercurial thermometer.

 This was about 1641.

 Ferdinand the II, in 1650 or  thereabouts, filled a glass tube with colored alcohol and hermetically  sealed it after graduating the tube.

 Fahrenheit is given credit for the  discovery that water freezes always at the same temperature.

 With these  facts he devised a scale for thermometers in 1714.

  THERMOMETER RECORDS  A temperature of 111° below zero has been recorded at an altitude of  48,700 feet in the United States.

  The highest record in the United States Weather Bureau was taken in  Death Valley, Cal.

, on June 30, July 1 and 2, 1891, when the thermometer  reached 122° F.

 Death Valley is also given credit for the highest known  monthly temperature, which was 102° F.

 in the month of July.

 Arctic  expeditions have records of 73° and 66° below zero.

 This is the greatest  natural cold recorded.

 The average temperature in the United States is  52.

4°; the average temperature in England is 50°.

  In the interior of Australia a record has been taken of a drop of 60° to  70° in a few hours; whereas the most rapid change recorded in the United  States was 60° F.

 in twenty-four hours.

 This record has been made twice,  in 1880 and again in 1890.

  The lowest temperature recorded in the United States Weather Bureau was  at Poplar River, Mont.

, January, 1885, when the thermometer registered  63° below zero.

  The estimated heat of the sun is 10,000°; the highest artificial heat  obtained is 7,000°.

 Regarding the heat of the sun, no definite  conclusions have been arrived at, so the above temperature is only  approximate.

 REGIONS OF LEAST RELATIVE HUMIDITY  Least relative humidity is found in places southwest of Arizona, where  the average is about 40°.

 Fifty degrees humidity means half as much  moisture as is necessary for complete saturation.

 The average in other  parts of the country is from 60° to 80°.

  Steel boils at 3500°; water boils at 212°; liquid air submitted to a  degree of cold where it ceases to be a gas and becomes a solid is 312°  below zero.

 Professor John Dewar of England is credited with some of the  most remarkable experiments with low temperature, and at these  temperatures made some wonderful discoveries.

 He went down so cold that  he could freeze liquid air back into a solid; he continued further until  he reduced hydrogen, a very light gas, to a liquid.

 This was at 440°  below zero.

 One of the most remarkable things he did was to freeze  hydrogen into a solid.

  Water boils at 183.

2° Fahrenheit on top of Mt.

 Blanc; water boils at  194° Fahrenheit on top of Mt.

 Quito.

  xxx BAROMETERS  Torricelli is given credit for the discovery of the principles of the  barometer.

 Otto Von Guericke, of Magdeburg, to whom we are indebted for  the air pump, is credited as being the first person to use the barometer  as a weather indicator.

  Because of the fact that the mercurial barometer is not adaptable for  portability, many scientists began work on producing a barometer without  fluid that could be easily carried about and would give accurate  results.

 In 1798 M.

 Comte, professor of aerostatics in the school at  Meudon near Paris, invented the aneroid barometer, which he used in his  balloon ascents.

 This instrument has been described fully on page 55.

 BAROMETER RECORDS  Lowest reading taken in the United States by the United States Weather  Bureau was 28.

48, or practically three quarters of a pound per square  inch below normal.

 Altitude records have been taken with the barometer  as high as 85,270 feet.

 This record was made at Uccle Observatory,  Belgium, the pressure being 0.

67° at this point.

  xxx  HAIL  Hail varies from one-tenth inch to more than five inches in diameter.

  The following is an extract from the "Memoirs of Benvenuto Cellini" of a  terrible hail storm in Lyons, France, in 1544: "The hail at length rose  to the size of lemons.

 At about half a mile’s distance all the trees  were broken down, and all the cattle were deprived of life; we likewise  found a great many shepherds killed, and we saw hailstones which a man  would have found it a difficult matter to have grasped in both
 hands.

"  New Hampshire has the record for the largest hailstones seen here so  far; they were 4 inches in diameter and weighed 18 ounces, and were 12½  inches in circumferences.

  xxx  RAINFALL  There are records in Japan of where rain has reached 30 inches in  twenty-four hours; in India where it has reached 40 inches in  twenty-four hours.

  The average rainfall in the United States is 35 inches.

  There are certain places in India where the yearly rainfall averages  over 470 inches; whereas other regions of India show less than 4 inches.

  The higher the clouds are in the air, the larger the drops of rain when  they reach the earth.

  The heaviest annual rainfall recorded any place in the world is on the  Khasi Hills in Bengal, where it registered 600 inches.

 The major part of  this was in half of the year.

  The greatest amount of rainfall is in the northwestern part of the  United States; the least amount is in Arizona, the southwestern part.

 In  some parts of Egypt and Arabia, the only moisture that is received there  is in the form of dew.

  The average cloudiness of the earth has been estimated between 50 and 55  per cent.

 This amount slightly exceeds the cloud conditions of the  United States.

  Unalaska has a record of extreme cloudiness for one whole month,  February, 1880.

  Sir J.

 C.

 Ross, an Arctic explorer, recorded a shower of nearly an  hour’s duration on Christmas day, 1839, without a cloud in sight.

  A similar record was made on June 30, 1877, at Vevay, Ind.

, where a  shower lasted for five minutes in a cloudless sky.

  A fall of yellow snow was recorded at South Bethlehem, Pa.

, in 1889.

  Examination showed this coloration to be due to the pollen of the pine  trees which had been blown into the atmosphere before the fall.

  Another record of yellow rainfall was recorded at Lynchburg on March 21,  1879.

  Golden snow was recorded at Peckoloh, Germany, in 1877.

  Green and red snows have been observed during Arctic explorations, due  to a minute organism that was in the atmosphere.

  When the temperature of the atmosphere is nearly 32° during a snow storm  and the wind is blowing, the flakes being damp and the snowfall heavy,  the flakes are apt to unite to form large masses of snow in the  atmosphere or air, which accounts for some
 of the following records:  At Chapston, Wales, in January, 1888, the snowflakes measured 3.

6 inches  in length and 1.

4 inches in breadth, and 1.

3 inches in thickness.

 They  amounted to 2½ cubic inches of water when melted.

  There are some remarkable instances of where hailstones have cemented  together, making large masses of ice.

 Some remarkable records of this  kind have been recorded in India.

  In Morganstown, Va.

, on April 28, 1877, hailstones 2 inches long and 1½  inches in diameter fell.

  The mean yearly pressure of the United States ranges between 30 and 30.

1  inches when reduced by ordinary methods to sea level.

  In Unalaska, January 21, 1879, the barometer reading of 27.

70 inches was  recorded, and another low reading was made at Stykkisholm of 27.

91  inches on February 1, 1877.

 On September 27, 1880, a ship on the China  Sea experienced a terrific typhoon, during which the barometer went down  in four hours from 29.

64 to 27.

04 inches.

  The greatest temperature ranges recorded are in the interior of Siberia,  where at Yakutsk they recorded a range of 181.

4°.

  The most remarkable changes recorded within twenty-four hours have been  at Fort Maginnis, Mont.

, January 6, 1886, a fall of 56.

40°; at Helena,  Mont.

, January 6, 1886, a fall of 55° in sixteen hours; at Florence,  Ariz.

, June 26, 1881, 65° rise.

 On the northern edge of the African  desert the temperature of the air rose to 127.

4°.

  The lowest single temperature in the world was recorded at Werchojansk,  Siberia, in January, 1885, when it was 90.

4° below zero, while the  average temperature for the month at the same place was 63.

9° below  zero.

  Highest mean rainfall occurs in Sumatra, averaging about 130 inches; the  rainfall of 493.

2 inches per year occurs at Cherapunji, Assam, India,  which is the largest in the world.

  The lowest rainfall in the world occurs at Southeast California, West  Arizona, and the valley of lower Colorado, where the rainfall averages  less than 3 inches.

  The most remarkable rainfall recorded in the United States for  twenty-four hours occurred at Alexandria, La.

, June 15, 1886, when the  rainfall reached the enormous amount of 21.

4 inches.

 The most remarkable  rainfall recorded in the world occurred at Purneah, Bengal, September  13, 1879, when the rainfall reached the unprecedented amount of 35  inches in twenty-four hours.

  xxx  CLOUDBURSTS  On August 17, 1876, at Fort Sully, Dakota, occurred one of the heaviest  cloudbursts ever known.

 The water moved out of the canyon on the  opposite side of the Missouri in a solid bank three feet deep and 200  feet wide.

 There are many other remarkable cloudbursts recorded doing  great injury, drowning and killing many people.

  xxx WIND VELOCITY  Among the most remarkable wind velocity records is that of Cape Lookout  on October 17, 1879, when the wind blew at a rate of 138 miles an hour.

  One of the worst cyclones ever recorded in North America was the flood,  as it is usually termed, at Galveston, Tex.

 This storm began on the 1st  day of September, 1900, and lasted until the 12th.

 It reached its  maximum destructive force on the 8th.

 Six thousand lives were lost and  $30,000,000 worth of property was destroyed.

  Even worse than any of these was the one at Calcutta in 1864, followed  by a storm wave over 16 feet high, causing a death-rate of 45,000  persons.

  xxx BLIZZARDS  The blizzard in Dakota of 1873 is one of the worst on record, but  probably the most disastrous in the United States occurred in Montana,  Dakota, and Texas on January 11, 1888.

 The loss of life exceeded 100  persons.

  xxx TORNADOES  The United States is more liable to tornadoes than any other part of the  globe.

 In the United States over 3,000 people have been killed by  tornadoes and thousands more have been injured.

 The greatest loss of  lives recorded by tornadoes was at Adams City, Miss.

, on June 16, 1842,  when 500 lives were lost.

  The most remarkable hail storm was that of July 13, 1788, through France  to Belgium, and did a property damage of over five million dollars.

  There have been many destructive hailstorms in the United States.

 One on  July 6, 1878, at central New York extended into parts of Massachusetts,  Rhode Island and Connecticut.

 Stones fell recorded to measure 7 inches  in diameter.

  ROTARY MOTIONS OF STORMS  Benjamin Franklin has been given credit for the discovery that storms  have a rotary motion, and that they move from west to east.

 This  discovery was made in 1747.

  Franklin did not positively prove these facts, and it remained for  Redfield, Espy, Maury, Abbe to substantiate the truth of this statement.

 THE FIRST UNITED STATES WEATHER BUREAU  The first United States Weather Bureau was established in 1870.

 General  Albert J.

 Myer was the first chief of the United States Weather Bureau.

  It is estimated that we are 250,000 miles from the moon.

  At high altitudes, the cover of a kettle must be weighted down in order  to boil an egg hard.

 This is to enable the pressure of steam to allow  temperature high enough for boiling.

 In other words, it would be  impossible to boil an egg in an open vessel at a high altitude.

  ------------------------------------------------------------------------  xxx MEMORANDUM  [Illustration] Rain Tomorrow!  You do not like your ball game or picnic postponed just because of rain,  do you? You want a bright day for that event.

 Then don’t guess what the  weather will be on a certain day-know.

 Learn to use the Gilbert Weather Bureau  to read weather indications from instruments set up by yourself-in your  own home.

 This is an outfit you will like immensely.

 Made specially for  your use and to provide you with a new kind of play.

  The fun you get in making records of changes in temperature, in  humidity, and in making forecasts will surely be great.

 Your boy friends  will listen to you with interest when you explain to them the cause of  storms and how important it is to have a knowledge of climatic  disturbances.

 The outfits contain all the necessary equipment and a big  book on weather, telling you how to know when it’s going to storm and  many other interesting things.

 Your dealer will show you the Gilbert  Weather Bureau Sets.

 If he hasn’t them, write THE A.

 C.

 GILBERT COMPANY 514 Blatchley Avenue  New Haven, Conn.

  In Canada: THE A.

 C.

 GILBERT-MENZIES CO.

, Limited, Toronto, Ont.

 In England: THE A.

 C.

 GILBERT CO.

, 125 High Holborn, London W.

C.

 1  [Illustration] WHAT IS SOUND?  Do you know that hearing is just feeling with the ear? That in reality,  the thing we call sound, which we think of as a noise or as a musical  note, is just an impression on the brain? Very few boys know this, and  if y
ou would like to be one of the few that do, you surely want an  outfit of Gilbert Sound Experiments  With one of these outfits you can find out just what sound is-how it is  produced-why some pianos sound better than others-why a violin produces  a musica
l tone, and many other things, including a number of startling  table rapping tricks with which you can astonish your friends.

 A big  book of instructions tells you how to perform every experiment.

 Get one  of these outfits today.

 The best toy dealer in your town should have it;  if not, write us and we’ll tell you where you can get it.

 THE A.

 C.

 GILBERT COMPANY  514 BLATCHLEY AVE.

  NEW HAVEN, CONN.

 In Canada: The A.

 C.

 Gilbert-Menzies Co.

, Limited, Toronto  In England: The A.

 C.

 Gilbert Co.

, 125 High Holborn, London, W.

 C.

 2  [Illustration]  In the Dark!  A knock on the head with a hatchet or a stab with a knife doesn’t sound  pleasant, but you’ll enjoy apparent treatment of this kind and so will  your friends who watch your shadow show.

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  ------------------------------------------------------------------------  xxx  TRANSCRIBER’S NOTES 1.

 P.

 67, changed "it means that there is one one-hundredth of an inch  of rain" to "it means that there is one one-tenth of an inch of  rain".

 [Makes the math consistent with the rest of the section.

] 2.

 P.

 68, changed "by one hundred for actual rainfall" to "by ten for  actual rainfall".

 [Makes the math consistent with the rest of the  section.

] 3.

 Silently corrected obvious typographical errors and variations in  spelling.

 4.

 Retained archaic, non-standard, and uncertain spellings as printed.

 5.

 Enclosed italics font in _underscores_.

 6.

 Enclosed bold font in =equals=.

  *** END OF THE PROJECT GUTENBERG EBOOK GILBERT WEATHER BUREAU (METEOROLOGY) FOR BOYS ***  Updated editions will replace the previous one-the old editions will  be renamed.

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s.

  zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

https://www.wunderground.com/history/daily/KLCK/date/2025-1-1
Everything the same cept year, month, day

Dewpoint The dew point is the temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity ...
Pressure
Relative humidity measure of the water vapor content of the air
Sky clover
Tempature1



The full book is here https://www.gutenberg.org/ebooks/67391
I will only extract part of the info

  WHAT IS THE WEATHER?  By the weather we mean the temperature, the amount of moisture in the  air, the pressure of the air, the movement of the air, and all the  conditions that have to do with the atmosphere, such as heat, cold,  rain, snow, sleet, fog,
 frost, dew, etc.

 It has to do with everything,  from calmness and clearness to cloudiness and blizzards.

 THE EFFECT OF THE SUN  The sun has a great deal to do with the regulation of the weather.

 Its  heat causes evaporation; it is the rays of the sun that raises the vapor  from the water and brings it into the air; it is the cooling of this  vapor that produces the rain, hail and sleet storms, and its brilliancy  causes a difference in air press
ure at times.

 It is this difference in  air pressure that produces winds, as you will learn later.

  HUMIDITY  The state of the air with respect to the vapor that it contains is  called its humidity.


 Dry air allows too much radiation from the body and too rapid  evaporation, which makes us cold.


FOGS  Water vapor in the air is transparent, but when this water vapor becomes  cooled, a portion of it becomes precipitated, which is no mo
re or less  than drops of water that are extremely small, but yet large enough to  become transparent, and the atmosphere in this state is called fog.