S. Department of Boriculture, 
 
 WEATHER BUREAU. 
 
 INSTRUCTIONS 
 
 FOR 
 
 VOLUNTARY OBSERVERS 
 
 PREPARED UNDER DIRECTION OF THE CHIEF OF THE 
 WEATHER BUREAU. 
 
 T. RUSSELL, 
 
 PBOFESSOB OF 
 
 PUBLISHED BY AUTHORITY OF THE SECRETARY OF AGRWULTU&S. 
 
 WASHINGTON, D. C.: 
 
 GOVERNMENT PRINTING OFFICE. 
 
 1892. 
 
ZIU S. Department ot Bgriculture, 
 
 WEATHER BUREAU. 
 
 INSTRUCTIONS 
 
 FOR 
 
 VOLUNTARY OBSERVERS 
 
 PREPARED UNDER DIRECTION OF THE CHIEF OF THE 
 M ^ . WEATHER BUREAU. 
 
 BY T. RUSSELL, 
 
 PBOFESSOB or METEOROLOGY. 
 
 PUBLISHED BY AUTHORITY OF THE SECRETARY OF AGRICULTURE. 
 
 WASHINGTON, D. C.: 
 
 GOVERNMENT PRINTING OFFICE 
 
 1892. 
 
GIFT 
 
 . .:*.; : : 
 
TABLE OF CONTENTS. 
 
 Page. 
 
 Introduction 9 
 
 Voluntary observer's form of application 11 
 
 Thermometers i 12 
 
 Minimum thermometers 15 
 
 Maximum thermometers 18 
 
 Instructions for setting up maximum thermometers 20 
 
 Instructions for setting up minimum thermometers 20 
 
 Thermometer shelter 22 
 
 Window or wall shelter J - 23 
 
 Daily mean temperature 24 
 
 Solar radiation thermometer 25 
 
 Thermoscope 26 
 
 Water vapor in air 27 
 
 Psychrometer 28 
 
 Sling psychrometer 29 
 
 Hair hygrometer 30 
 
 Barometer , 30 
 
 Vernier 33 
 
 Correction of barometric observations 38 
 
 Aneroid barometer 41 
 
 Hypsometer 42 
 
 Rain gauge 43 
 
 Instructions for use of rain gauge 44 
 
 Rain gauge support 46 
 
 Percolation gauge 49 
 
 Wind vane 50 
 
 Anemometer - 51 
 
 Clouds 55 
 
 Evaporation ..." 57 
 
 River gauge 58 
 
 State of weather 60 
 
 Frost - 60 
 
 Coronas 60 
 
 Thunderstorms 61 
 
 Tornadoes and Sand spouts 61 
 
 Instructions for observing Auroras 61 
 
 Earthquakes 64 
 
 General phenomena of Climate 66 
 
 Special instructions to voluntary observers 67 
 
 Instructions in the use of the tables 69 
 
 Table I. Temperature of the dew point 71 
 
 II. Relative humidity, per cent 81 
 
 III. Correction of vapor pressure 91 
 
 IV. Vapor pressure in inches 92 
 
 V. Grains of water-vapor in a cubic foot of air 93 
 
 VI. Reduction of barometer readings to 32 94 
 
 VII. Reduction of observations of barometer to sea level 96 
 
 795 8 
 
LIST OF ILLUSTRATIONS. 
 
 Page. 
 
 Figure 1. Maximum and minimum thermometers 19 
 
 2. Design for thermometer shelter 22 
 
 3. Solar radiation thermometer 25 
 
 4. Alcohol radiation thermometer 25 
 
 5. Mounting of barometer 31 
 
 6. Vernier 35 
 
 7. Vernier 35 
 
 8. Vernier 35 
 
 9. Barometer cistern and scale 37 
 
 10. Barometer cistern section 37 
 
 11. Aneroid barometer 41 
 
 12. Eain gauge, front view 45 
 
 13. Kain gauge, vertical section 45 
 
 14. Rain gauge receiver 45 
 
 15. Rain gauge receiver, horizontal section 45 
 
 16. Rain gauge and support 46 
 
 17. Wind vane 50 
 
 18. Anemometer 51 
 
 19. Anemometer dial 54 
 
 20. Piche evaporometer 58 
 
 21. River gauge 59 
 
 7 
 
INSTRUCTIONS TO VOLUNTARY OBSERVERS OF THE WEATHER 
 
 BUREAU. 
 
 INTRODUCTION. 
 
 To render the meteorological observations made over the United 
 States of the greatest value, and for ease and facility in their use in 
 the investigation of questions relating to the weather, it is important 
 that they be made on a uniform plan and the records kept on some 
 uniform system. 
 
 With a view to accomplishing this, a general description is here 
 given of the best methods of making meteorological observations 
 and the instruments used for the purpose. This is prepared specially 
 for the information of the voluntary observers of the United States 
 Weather Bureau under the Department of Agriculture. 
 
 Observations have a two-fold object : First, to obtain a knowledge 
 of the climate of a region, that is, the average of the .various air- 
 conditions over a country that affect the convenience, comfort, or 
 health of the people, or influence plant growth ; second, the dis- 
 covery and improvement of rules and methods for making weather 
 predictions. For this purpose the observations over an extensive 
 area of country are used to trace the origin, direction, and rate of 
 progress of pressure and temperature changes in the air, the occur- 
 rence of rainfall, and the direction and velocity of wind as dependent 
 on the variety in distribution of pressure and temperature over a 
 region. 
 
 The successful predictions of the principal weather changes, such 
 as cold waves, storm winds, heavy rainfalls, and great river floods, 
 are of the highest practical value to people. The attainment of this 
 important object, even with only a partial degree of success, is a 
 sufficient motive for the labor bestowed in making and preserving 
 the vast amount of weather observations now going on in most 
 countries all over the world. 
 
 Observations are desired in at least one place in every county of 
 every State in the United States. For the purpose of procuring 
 these observations the Chief of the Weather Bureau is authorized by 
 law to loan instruments to observers desirous of making the observa- 
 tions, but on certain conditions. These conditions are the safe keep- 
 ing and return of instruments, and that a copy of the observations 
 be furnished to the Weather Bureau Office, Department of Agri- 
 culture, at Washington, D. C., free of expense to the United States 
 Government. 
 
 9 
 
i fc - 10 
 
 G'f fimiry"' precautions "'arfe required in the use of instruments. 
 Observers are not, however, held responsible for the breakage or loss 
 of instruments due to unavoidable accidents incident to their use in 
 the making of observations. 
 
 The observations in which the Weather Bureau is most interested 
 are rainfall and temperature. Thermometers and rain-gauges are 
 furnished to the observers free of any charges for instruments or 
 for transportation to the observers. 
 
 Blank forms and franked envelopes are furnished to the observers 
 for transmission of reports to Washington, D. C., free of expense to 
 the observer. Observers ajre also furnished free with a copy of the 
 Monthly Weather Review, an official publication which gives a sum- 
 mary of the weather all over the United States for each month, the 
 mean temperatures and total rainfalls for places, descriptions of 
 progress of principal storms, cold waves, and floods during the 
 month, etc. 
 
 Voluntary observers are not furnished with barometers, wind- 
 vanes, or anemometers. Many of the observers have these instru- 
 ments, their own private property, and instructions are, therefore, 
 here given regarding their use and care. 
 
 Observations of air pressure and wind velocity by voluntary ob- 
 servers are not desired by the Weather Bureau. Enough data of 
 this nature for the purposes of the Bureau, the forecasting of weather, 
 are obtained from the regular meteorological stations. Observa- 
 tions of pressure by voluntary observers are mainly of interest to 
 the observers themselves at the time of the observation in esti- 
 mating the location of storm centers in vicinity where there is no 
 access to the daily weather map issued by the Weather Bureau. The 
 detailed or average values of pressures are of little value for climate. 
 The rainfall and temperature observations are intended to be used 
 in the Weather Bureau in working up the climatology of the whole 
 country. 
 
 A trustworthy record of the weather is always of interest to any 
 community, and is often of very great practical value. It is one of 
 the objects of the Weather Bureau to foster and encourage the keep- 
 ing of such records. There are numerous calls for records of the 
 weather as evidence in courts in important law cases months, and 
 even years, after the record is made. Contractors and others inter- 
 ested in outside work often want a record of days when there was 
 rain or high winds, when streams were frozen over or swollen with 
 floods, etc. Farmers are interested in the state of the season, 
 whether forward or backward, as regards temperature and rainfall. 
 A double supply of blank forms is furnished observers in order that 
 a copy of the weather record may be retained for their own use. 
 
 A person desiring to become a voluntary observer is requested to 
 fill out a form (No. 4006), a specimen of which is shown below. 
 
11 
 
 [FORM No. 4006 Mis.] 
 
 APPLICATION FOR METEOROLOGICAL INSTRUMENTS. 
 
 I, , County of , and State of , do hereby request to be 
 
 furnished with one maximum thermometer, one minimum thermometer, and one 
 standard rain-gauge, with the necessary supports, for use in making daily observa- 
 tions of temperature and precipitation, and Thereby agree to send a monthly report of 
 such observations on Form No. 1008, Meteorological blanks and penalty envelopes to be 
 furnished by the Weather Bureau to the Observer, Weather Bureau, . 
 
 I do further agree to RETURN all of said instruments to the Observer, Weather 
 
 Bureau, , or to turn them over to a duly appointed successor, whenever, 
 
 from any cause, except sickness or unavoidable absence from home, I fail to make the 
 observations hereinbefore agreed upon. 
 
 I further agree to exercise a reasonable degree of care in handling the above- 
 named instruments, to care for them as I would my own property, and to return those 
 which may be accidentally broken or otherwise become unserviceable, with a state- 
 ment covering the circumstances which caused the damage. 
 
 (Signature) 
 
 I,- , postmaster of , do hereby certify that , who 
 
 signs the above application, is personally well known to me, and I fully believe him 
 to be a responsible person, and that he will faithfully perform the obligations assumed 
 by him in his application. 
 
 (Signature) 
 
 Postmaster. 
 (Date) , 189 . 
 
 U. S. DEPARTMENT OF AGRICULTURE, 
 
 WEATHER BUREAU, 
 
 (STATION) 
 
 Issued maximum thermometer No. , minimum thermometer No. , rain- 
 gauge No. ,and notified the central office. 
 
 Observer, Weather Bureau. 
 (Date) , 189 . 
 
 The observer is accepted if there is not already one in the vicinity. 
 A list of the various observers and their location is published every 
 three months in the Weather Review. 
 
 Voluntary observers receive no pay for services. 
 
 . METEOROLOGICAL INSTRUMENTS. 
 
 The most important conditions of the air, the subject of inves- 
 tigation, and the instruments used in observing them are as follows: 
 
 Temperature observed by means of thermometers. 
 
 Water- vapor pressure in air, measured with dew-point apparatus or psychrometer. 
 
 Pressure, observed with mercurial barometer, aneroid barometer, and hypsometer. 
 
 Rainfall, measured with rain-gauge. 
 
 Rainfall, reaching different depths in the earth, measured with a percolation 
 gauge or lysimeter. 
 
 Snowfall, melted, measured with a rain-gauge. 
 
 Wind direction, observed by a wind vane. 
 
 Wind velocity, measured by an anemometer. 
 
 Clond motion, observed with nephoscope. 
 
 Cloudiness, amount in fractional part of the sky covered, estimated with the eye. 
 
 Sunshine duration, measured with a sunshine recorder. 
 
 Electrical potential, measured with an electrometer. 
 
 Evaporation, measured with evaporometer. 
 
 Fog, haze, estimated. 
 
12 
 
 In river observations the important conditions are: 
 
 River stages, the vertical height in feet of river surface above low water, 
 observed on a river-gauge. 
 
 River-current velocity, measured with a current-meter or ship's log. 
 
 THERMOMETERS. 
 
 The most important condition of the air is temperature. A mer- 
 curial thermometer used in observing- temperature consists of a glass 
 bulb and stem containing mercury. Substances expand slightly with 
 heat. Mercury expands seven times as much as glass. The height 
 of the top of column of mercury in the stem is a measure of the 
 temperature. The thermometer takes the temperature of the air by 
 the contact of particles of air with the bulb. 
 
 The best forms of thermometers have the graduations etched on 
 the glass-stem of the instrument. 
 
 On the Fahrenheit scale, the only scale in use in meteorological 
 observations in the United States, the temperature of the melting 
 point of ice is taken as 32, usually called freezing point, and the 
 temperature of boiling water under a standard pressure of the air 
 of 29.922 inches, as 212, usually called boiling point. 
 
 The temperature of melting ice varies slightly with the pressure 
 of the air. Doubling the pressure of the atmosphere lowers the 
 temperature 0.0135 ot a degree. This must be distinguished from 
 the effect of an additional pressure of an atmosphere on the bulb of 
 a thermometer. For an ordinary thermometer the increase of pres- 
 sure on the bulb for one atmosphere compresses the bulb to such an 
 extent that the column of mercury in the stem will stand 0.5 of a 
 degree higher than without the pressure. 
 
 When a thermometer is made, the stem is closed with the mercury 
 near the top, so that it contains very little air. When the top of the 
 stem is broken, admitting the pressure of the outside air, the reading 
 is lowered about 0.5 of a degree. 
 
 At boiling point, doubling the pressure of the air raises the boiling 
 point to 250. 
 
 The volume of the stem from 32 to 212 is divided into one- 
 hundred and eighty equal parts by the graduations of the scale. 
 The temperature corresponds to the graduation the mercury reaches 
 on stem numbering the degrees consecutively from 32 up, and 
 numbering down consecutively below 32. 
 
 The indications of a mercurial thermometer are trustworthy as 
 low down as temperatures on the very verge of the melting point of 
 frozen mercury, 37-9. Mercury vaporizes at a temperature of 
 6 42 .6. 
 
 For very accurate temperatures several requirements are neces- 
 sary. The thermometer used in taking the temperature should be 
 compared with a standard thermometer by comparative readings of 
 
13 
 
 the two instruments at different points along the scale in water kept 
 thoroughly stirred. For points below 32 the comparisons have to 
 be made in a bath of alcohol. In this way a list of corrections of 
 the thermometer is made, which are to be applied to any readings 
 made in order to obtain the true temperature. 
 The following is a specimen: 
 
 SCALE READING. 
 
 CORREOTIO: 
 
 -28 
 
 -f 1.0 
 
 -18 
 
 + 0. 4 
 
 8 
 
 -0. 2 
 
 4 2 
 
 0. 6 
 
 12 
 
 1.1 
 
 22 
 
 0. 6 
 
 32 
 
 0. 4 
 
 42 
 
 -0. 3 
 
 52 
 
 -0. 1 
 
 62 
 
 + 0. 1 
 
 72 
 
 + 0. 3 
 
 82 
 
 + 0. 5 
 
 92 
 
 + 0. 8 
 
 102 
 
 -fl. 1 
 
 The correction should be applied algebraically to the scale read- 
 ing of the thermometer. For a temperature not given in the list 
 of scale readings, an interpolated value of the correction is used. 
 For the reading of 67.5 for instance, the correction is + - 2 and 
 the true temperature 670.7; for 22 the correction is 0.6 and the 
 true temperature 21. 4. 
 
 Caution is required in applying the correction to a minus scale 
 reading when the temperature is below zero. For the reading of 
 
 28.o, for instance, the correction is + i.o; the true temperature is 
 
 28.0 4- i.o = 27.0. In applying the correction, like signs add, 
 dissimilar signs subtract. 
 
 There is a constant rise in the freezing point of a thermometer 
 with age, due to a slow and steady contraction of the glass bulb. A 
 thermometer graduated the day it is filled will read a degree and a 
 half higher a week after. Good thermometers are not graduated 
 until a year or two after filling. In the course of three years the 
 freezing point will rise a half degree. This varies very much in 
 different instruments, depending on the nature of the glass. Some 
 varieties of glass are now used in making thermometers that vary 
 very little with age. 
 
 Any change in the freezing point of a thermometer changes the 
 whole series of corrections throughout the scale correspondingly. 
 In the case of the thermometer above, if the correction at freezing 
 point is found on packing the instrument in melting ice at some 
 future time to be 0.9 of a degree instead of 0.6; that is, if its 
 reading in ice is 320.9 instead of 320.6 as would be the case now, then 
 there is a change of 0.3 of a degree throughout the scale, the instru- 
 
14 
 
 ment reading that much higher at every point. The correction at 
 62 instead of being o.i will be 0.4 at 72, instead of -f o.i; it 
 will be 0.2, etc. 
 
 After a thermometer has been heated to a very high temperature, 
 as the boiling point, there is a depression of the freezing point of 
 about 0.4 of a degree, which is fully recovered in six weeks. Sub- 
 jecting a thermometer to a very high temperature, as 500, raises the 
 freezing point permanently from 10 to 1 8. Long exposure to a low 
 temperature as 30 will raise the freezing point about o.i of a 
 degree. 
 
 The valid freezing point correction to be used in correcting the 
 indications of a thermometer to the true temperature is the freezing 
 point correction observed just after exposure of the thermometer to 
 the temperature. Ordinarily for such range as there is in the 
 temperature of the air the freezing point observed once a year gives 
 the correction with sufficient accuracy to o.i of a degree. 
 
 Thermometers are made with cylindrical and spherical bulbs. 
 The cylindrical form is the most popular at the present time. It is 
 usually more sensitive than a spherical bulb, as it exposes more 
 surface to the air for the same quantity of mercury contained. 
 Spherical bulbs can, however, be blown thinner than cylindrical 
 ones, and the glass is commonly more uniform in thickness. 
 
 In observations of rapid change of temperature, as in a balloon 
 ascent, a thermometer has to be very sensitive to give a correct 
 result. In fact a correction has to be applied where accuracy is 
 required. A thermometer may sometimes be found in error from a 
 break in the column of mercury or from a bubble of air in the bulb. 
 
 A thermometer to be in the best condition ought not to have its 
 column broken when held with the bulb uppermost. To remove 
 the air the speck in the bulb should be first brought to the junction 
 of the stem and bulb by jarring the latter in the open palm of the 
 hand. When the speck is at the junction, prepare ice or snow or 
 cold water and cool the bulb down, then invert it, and all the mercury 
 will run to the other end, or may be made to do so by a gentle jar, 
 Now heat the bulb, either in the hand or at a long distance from a 
 heated surface, being careful to hold the stem horizontal or inclined, 
 with the bulb end up. This will cause the mercury to rise and drive 
 the air before it. Care should be taken never to heat so much that 
 the top of the column is less than a half-inch from the end of the 
 other detached column, as otherwise the thermometer may be broken. 
 If, now, the thermometer is held vertically the two columns will join, 
 or may be made to do so by a gentle jar in the open palm of the hand; 
 the air speck will be in the tube, but the mercury will join by a 
 slender thread alongside of the speck. Now, if the bulb be cooled, 
 the air-speck will remain stationary, but the mercury will flow past 
 it toward the bulb. 
 
15 
 
 By repeating the process the speck may be finally driven into the top 
 of the tube, where it will do no harm. In cooling off the thermometer 
 for the last time care should be taken that the speck in the column 
 be at a point before inversion which is above the temperature of the 
 cooling liquid, otherwise the column left after cooling down will be 
 so short that it cannot be driven down on inversion. If it be found 
 impossible to get the short column down on inversion after cooling, 
 it may be easily lengthened by jarring the bulb in the open hand, 
 holding the bulb down. In case there is much air separating the 
 two columns it will be found impossible to unite them when the 
 upper column is quite short, the air-speck being so large that the 
 thread of mercury cannot pass it. In such case it may be necessary 
 to heat the upper part of the tube quite hot where there is no mer- 
 cury. This expands the air and brings a slight pressure to bear upon 
 the top of the mercury. If the thermometer while still hot be jarred 
 upon the open hand the columns will frequently unite. If all other 
 efforts fail take the tube from the brass scale and gradually heat the 
 part above the main column in an alcoliol flame, by running it back 
 and forth in the flame and twirling it continually in the fingers, in 
 order to heat it uniformly. 
 
 The mercury will be volatilized and scattered along the bore. 
 Then by heating up the thermometer the main column will take up 
 the various detached portions. Some thermometers are provided 
 with an expansion chamber at the top of the tube, and in such case 
 it is only necessary to heat the bulb until the air-speck has been 
 driven into the chamber. After that, by holding the bulb down, on 
 cooling it will be found that the air has remained behind and there 
 is a continuous column of mercury. In the latter kind of thermom- 
 eter it will frequently be found that a portion of the mercury has 
 lodged in the chamber, and is entirely separated from the column 
 in the tube. In such case a slight jar will sometimes send the 
 mercury down. If this does not avail then the bulb should be 
 warmed till the column in the tube reaches the mercury in the 
 chamber. When this is done, after cooling it will be found that the 
 column is perfect. Sometimes the chamber becomes completely 
 filled, and no effort can dislodge the mercury. In such case it is 
 necessary to heat the chamber in an alcohol flame, being careful to 
 turn the tube in the hand in order to apply the heat uniformly. In 
 a short time the murcury will be expanded sufficiently to flow down 
 the tube on its being held with the bulb down. A flame should 
 never be brought into contact with a thermometer bulb. 
 
 MINIMUM THERMOMETERS. 
 
 For temperatures below the freezing point of mercury alcohol 
 thermometers are used, standardized by comparison with a gas ther. 
 mometer at low temperatures. The alcohol minimum thermometer 
 
16 
 
 is the only trustworthy form of minimum thermometer for observ- 
 ing the lowest temperature reached by the air. 
 
 Alcohol thermometers are not as accurate as mercurial. The 
 alcohol wetting the glass surface makes the reading unequal at 
 different times. Even with the greatest care an accuracy of 0.6 of a 
 degree is the best that can be attained. The errors are liable to be 
 much larger at times on account of air bubbles forming in the column 
 or part of the alcohol evaporating and lodging in the upper part of 
 stem. 
 
 An index half an inch long made of enamel is fitted loosely in the 
 bore of the stem and immersed in the liquid. When the temperature 
 falls the index is carried along the bore and the top stops at the 
 lowest point reached by the top of the alcohol column. The reading 
 of the top of the index gives the lowest temperature. It is reset for 
 another observation by raising the bulb end of the thermometer, 
 which causes the index to slide down the bore until it stops at the 
 end of the column of alcohol. 
 
 The minimum thermometer is set nearly horizontal, with the bulb 
 end lower than the top. Jarring by the wind is apt to displace the 
 index and make it read too low. 
 
 Bubbles are apt to develop in the bore or bulb, and, making a break 
 in the continuity of the alcohol column, make the top read too high. 
 
 An instrument must be carefully examined from time to time for 
 the formation of alcohol in the bore above the column, which causes 
 the instrument to read too low. 
 
 Instructions. The many different ways in which the alcohol becomes 
 separated make it impossible to unite it by any single method, 
 different methods being required not only for different conditions, 
 but also for different thermometers. 
 
 Frequently there are only a few short detached portions near the 
 top, and the index slides freely along the lower portion of the tube 
 and drops into the bulb. Again, the detached columns are sometimes 
 found all along the tube, and the index is caught and held at some 
 point above the main column. In such a case it is advisable to first 
 bring the index into the bulb, as follows: 
 
 First process. Hold the thermometer lightly between the thumb 
 and fingers and strike the lower end of the metallic scale against the 
 top of a table, or other firm object; first, however, interposing one 
 or two thicknesses of cloth, or several folds of paper, so as not to 
 produce too severe a shock upon the thermometer. The taps of the 
 thermometer should be made light at first, and the index examined 
 to see if it has not moved along the tube even a little distance, as 
 can be told by noticing the exact position of the index in reference 
 to the graduations on the tube. If several taps fail to move the 
 index, increase the force of the taps, a little at a time, until the index 
 starts, after which repeat the operation until the index gets within 
 
17 
 
 the continuous column. Here it will fall of its own weight into the 
 bulb. Generally, this will be all that is necessary to place the index 
 in the bulb. Sometimes the detached columns will also have been 
 partly or wholly united. If the column is still broken in places the 
 observer should try a few more taps and quickly examine, very care- 
 fully, if very small portions of the alcohol cannot be seen slowly 
 moving along the sides of the tube toward the main column. If this 
 is the case a continuation of the taps will unite the columns; on the 
 other hand, and in case the index cannot be made to move with quite 
 hard taps, it is advisable to try some of the methods described next, 
 being careful always to avoid carrying any process so far as to 
 endanger breaking the thermometer. 
 
 Second process. Grasp the thermometer securely a little below the 
 middle, with the bulb end down, and strike the edge of the metal 
 back opposite the broken column sharply against the fleshy portion 
 of the palm of the other hand, or, if necessary, against a small block 
 of wood held in the hand. A continued jarring in this way often 
 causes the alcohol to run down, though in many cases a large number 
 of taps are necessary. Observers should, therefore, not give up if 
 the column does not unite at once, but should watch very closely for 
 the movements of small portions of alcohol along the sides of the 
 tube. Here, again, care must be exercised not to strike too hard, 
 and to hold the thermometer by the metal back in such a manner as 
 not to squeeze or press against the stem of the thermometer itself. 
 
 When the bore of the thermometer is large the above process is 
 almost sure to unite the column. Good results are also obtained 
 with thermometers of fine bore, though the latter often require some 
 time if the column is badly scattered. 
 
 Third process. This method can also be used in place of those 
 above, and is sometimes effective in forcing the index into the bulb. 
 Grasp the thermometer a little above the middle, holding it horizon- 
 tally, clasping the fingers and hand firmly against the edges of the 
 metallic back, but not so as to bring any pressure upon the glass tube, 
 which should be turned toward the person and with the bulb toward 
 the front. With the thermometer in this position and about as high 
 as the head, and the arm free from the body, quickly lower the arm 
 and hand a foot or more, turning the wrist at the same time, so that 
 the bulb of the thermometer describes a somewhat circular path 
 downward through the air, stopping the motion with a sudden jerk 
 just as the thermometer is vertical. If the thermometer is grasped 
 properly a very violent motion can be given in this way without 
 danger. It will sometimes be necessary to repeat the operation a 
 large number of times to entirely unite the detached columns. 
 
 When all the bubbles have been removed from the alcohol column, 
 the observer can then see how the instrument works. Hold the ther- 
 mometer vertically and warm up the bulb by holding it in the hand; 
 
18 
 
 then turn the instrument upside down. Watch the index as it glides 
 along the tube ; when it strikes the top of the column it will at once 
 stop. This operation of bringing the index to the top of the column 
 is called " setting" the thermometer. Next hold the thermometer 
 horizontally and remove the hand from the bulb. As the latter cools 
 off the index will be dragged backwards toward the bulb, but always 
 remains at the end of the column of alcohol. It is a good plan to 
 hasten the cooling by placing a little wet cloth or piece of ice against 
 the bulb. When you have watched the index go down with the 
 column, warm the bulb again with the hand. The column will go 
 up immediately, but the alcohol will flow around the index and leave 
 it at the lowest point. That is, the index remains so that its top end 
 is at the lowest point reached by the alcohol column, and the mini- 
 mum temperature is indicated in this way. The thermometer must 
 be held horizontally throughout these operations. 
 
 When the thermometer is not in use for observation it is a good 
 plan to hang it up, as bubbles are less likely to form in the tube in 
 this position. 
 
 MAXIMUM THERMOMETERS. 
 
 For observing the highest temperatures occurring during the day 
 a maximum thermometer is used. The form of maximum in use by 
 the Weather Bureau is a mercurial thermometer with a contraction 
 in the bore of the tube near the bulb. 
 
 When cooling of the instrument sets in the thread of mercury in 
 the bore separates from the rest at the point of contraction, leaving 
 the top of the column near the highest temperature reached. It is reset 
 for another observation by whirling it on a pivot at the top of the 
 metal strip to which the tube is attached. The centrifugal force 
 developed drives the detached thread back to the main body of 
 mercury. 
 
 When a maximum thermometer is not read for several hours after 
 the highest temperature has occurred and the air in the meantime 
 has cooled down 15 or 20, the highest temperature indicated by 
 the top of the detached thread of mercury may be too low by half a 
 degree from the contraction of the thread. 
 
 When the fall of temperature from the highest point is very slow 
 a little of the mercury may pass down before the thread breaks, 
 especially when there is no wind to cause a slight jarring of the 
 instrument. 
 
 In some instruments the narrowing of the bore develops a strong 
 capillary action, and when the connection of the column is broken 
 the detached thread jumps up a little, causing it to register a little 
 too high. This is most apt to occur in very cold weather when the 
 detached columns are very short. It also occurs with longer 
 detached columns when the thermometer is nearly horizontal. 
 
19 
 
 The cut below shows the appearance of the maximum and mini- 
 mum thermometers when properly attached to the wooden board 
 and supports furnished with the thermometers. 
 
 The upper thermometer is the mini- 
 mum. The lower thermometer is the 
 maximum. All new maximum and min- 
 imum thermometers have their respective 
 names stamped upon the metallic backs. 
 
 The maximum thermometer is always 
 rilled with mercury, sometimes called 
 quicksilver. All maximum thermome- 
 ters have a round brass hub-shaped pro- 
 jection fastened to the top of the back. 
 
 The most distinctive peculiarity of the 
 maximum thermometer, however, is not 
 so easily seen as those mentioned above. 
 If observers will hold the thermometer 
 vertically, with the bulb down, they will 
 r-; notice that the merciirial column does not 
 g extend entirely into the bulb. A very 
 close examination of the thermometer at 
 the point just above the bulb, where the 
 mercurial column stops, will show that 
 the glass tube seems to have been squeezed 
 almost together at that point, as appears 
 in the above drawing. . This is just what 
 has been done, and the passage-way for 
 the mercury is so fine at that point that 
 the mercury will only go through with 
 some difficulty. The observer should next 
 hold his fingers around the bulb. Pres- 
 ently the mercury in the bulb, as it be- 
 comes warm, will be forced to pass the 
 constricted portion of the tube, flowing 
 through in little spurts. When the fingers 
 are removed from the bulb the mercury 
 below the constriction withdraws toward 
 the bulb, but none of the mercury above the constriction can get 
 back and the column remains just the same length as it was when 
 the bulb was warmest. In this way the maximum temperature 
 is registered. 
 
 Observers sometimes think the above-described constriction in 
 the tube is a defect, but such is not the case, and no effort should 
 be made to cause the column to completely unite at this portion of 
 the tube. 
 
 1)3773 
 
20 
 
 Some forms of "exposed" thermometers look like maximum ther- 
 mometers, but observers should never have the least difficulty in 
 telling one from the other. The maximum thermometers used by 
 the Weather Bureau always have the constriction, and only maxi- 
 mum thermometers have the "hub" at the top of the metallic back. 
 
 If it is desired to set the maximum thermometer before placing 
 in position on the supports, this may be done by following the in- 
 structions given in the "third process" for minimum thermometers, 
 by which means the column of murcury will be driven back into 
 the bulb and the instrument "set" at the current temperature. 
 
 INSTRUCTIONS FOR SETTING UP MAXIMUM THERMOMETER. 
 
 For the support of the maximum thermometer, the long brass pin 
 with a nut must be screwed into the board in the hole to the extreme 
 right. The nut must be taken off and the pin slipped through the 
 hole in the upper end of the instrument, and then secured by replac- 
 ing the nut and screwing it tight. The plain brass pin must then 
 be inserted in the hole on the left of the board, and the thermom- 
 eter placed upon it, so as to slightly incline in that direction. The 
 end of the pin to which the maximum thermometer is attached must 
 be occasionally oiled to prevent friction. The maximum thermom- 
 eter is read by observing the number of degrees upon the scale at the 
 top of the column of mercury. After having taken a reading, the ob- 
 server must remove the pin at the left and then take hold of the 
 thermometer about 3 inches from the top and spin it ar^tmd 
 several times in the direction of the motion of the hands of a watch, 
 until the bulb and stem below the constriction are filled with mer- 
 cury. Care must be taken not to touch the bulb, and also that the 
 nut is screwed up sufficiently tight to prevent the instrument from 
 striking against the side of the board to which it is fastened. After 
 adjustment, gradually raise the instrument to a nearly horizontal 
 position and insert the pin as before. Care must be taken in ele- 
 vating the instrument not to raise the bulb too high, as the column 
 of mercury would then break and run to the upper end of the tube. 
 
 INSTRUCTIONS FOR SETTING UP MINIMUM THERMOMETER. 
 
 The brass support (a long, thin, narrow piece of curved brass, 
 containing two screw-holes near the center), to which the minimum 
 thermometer is attached, will be secured to the board in the follow- 
 ing manner : 
 
 The first screw-hole will be made 8 inches from the inner edge of 
 the bevel at the end of the board on the right, and $/& inch below 
 the inner edge of the bevel on the top of the board. 
 
 After securing the brass support to the board with the// screw, 
 attach the thermometer by screwing it to the support, and let the 
 lower end of the thermometer-scale rest in the notch cut in brass 
 
21 
 
 support to the left. Then bring the left end of the support to such 
 a position that the upper edge of the thermometer-scale will run 
 exactly parallel with the edge of the board. The second screw will 
 then be inserted, which will secure the brass support firmly to the 
 board. 
 
 The minimum thermometer, when attached to the support in this 
 manner, will then be exactly horizontal, which position is best 
 adapted to prevent any movement of the index not caused by the 
 actual changes in temperature. The top of the thermometer must 
 be fastened by the small brass screw upon the support and the 
 lower end dropped into the notch to the left, after having been 
 raised sufficiently to allow the small index in the tube to move 
 down to the top of the column of spirit. This instrument is read by 
 observing the number of degrees on the scale where the top of the index 
 rests. 
 
 If, at any time, the column should be found to be broken and 
 bubbles are observed in the tube, the instrument should be taken 
 off the supports and an effort made to unite the column, as given 
 above. 
 
 To " set " the minimum thermometer after a reading has been 
 made, the bulb, or lower end of the thermometer, must be elevated 
 a few inches until the index moves down to the end of the column 
 of alcohol, and then carefully lowered into the notch at the left of 
 the brass support, as before. 
 
 After resetting the maximum and minimum thermometers, the 
 top of the mercurial column of the maximum and the top of the 
 alcohol column of the minimum should read alike. 
 
 Example : The above illustration represents the thermometers 
 just after they have been set. It will be seen that the top of the 
 mercurial column of the maximum indicates a reading of 89. The 
 top of the alcohol column and the top of the index of the minimum 
 show the same reading, 89. This indicates that the two instru- 
 ments have been properly set. 
 
 The instruments must be set, in the manner described, once 
 each day, immediately after taking the observation. In no case 
 must they be set at any other time. 
 
 The wooden boxes and packing material received with these ther- 
 mometers should be carefully preserved for use in returning instru- 
 ments. 
 
 In packing thermometers for transportation each instrument must 
 be carefully wrapped in sheet cotton; the whole surrounded with 
 excelsior, or other packing material, in the wooden box, and, to pre- 
 vent shifting, all spaces should be filled with cotton. The lids of the 
 wooden boxes should always be secured with screws, as the jarring 
 resulting from driving nails into the wood is liable to break the 
 thermometer. 
 
22 
 
 THERMOMETER SHELTER. 
 
 To take the temperature of the air the thermometers are set up 
 inside of a cubical wooden lattice work inclosure called a shelter. 
 To get the temperature of the air accurately a thermometer must be 
 protected from the direct rays of the sun, which cause it to read too 
 high. Without a covering in the night time by radiation to the sky 
 a thermometer is apt to read too low. The ground is cooler than the 
 air at night, but the effect of ground radiation on a thermometer is 
 inappreciable at a greater height than 4 feet above the ground. 
 
 A thermometer in quiet air in the sunshine may read 10 or 
 more higher than the air temperature, depending on the strength 
 of the wind prevailing at the time. With the air perfectly calm 
 it may read even 20 higher. With a wind of twenty miles 
 an hour it will read only a few tenths of a degree higher than the 
 temperature in the shade, which is the true temperature of the air. 
 Moving particles of air coming continually in contact with the bulb 
 rapidly carry away the heat received from the sun. When there is 
 no wind a thermometer bulb creates a local atmosphere of warm air 
 around it. In a vacuum where all contact with air is shut off, a 
 thermometer in the sunshine becomes greatly heated. A thermom- 
 eter in the sunshine whirled rapidly will read about half a degree 
 higher than the true air temperature. 
 
 The reading of a thermometer in the sunshine in nearly quiet air 
 is not a meteorological datum of any value. 
 
 The form of shelter shown below and described, has been found 
 after years of experience to be the best adapted for the purpose. 
 
 
 fi" 
 
 8* 
 
 r^^ 
 
 6" 
 
 8" 
 
 36 
 
 DJ 
 
 
 36" 
 
 
 
 
 
 B_ 
 
 42 
 
 36' 
 
 42" 
 
 Section thr<f 
 Scale 1=50" Scale 1 = 5 
 
 4" 
 
 Section, thro* A.B 
 Scale 2*5" 
 
 FlG. 2. DESIGN FOR THERMOMETER SHELTER. 
 
 The frame is cubical, 3 feet on a side. The bottom is of close 
 boards, pine, % inch thick. The roof is double, sloping 8 inches 
 
-23 
 
 from front to rear, with 6 inches between. The high or front side 
 is made to face north. The front has a door 15 inches wide the 
 whole length of side, and opens down. The sides are of blind work; 
 the slats of white pine 3^ inches wide and ^ inch thick, slop- 
 ing at an angle of 45 to the horizontal. The distance from 
 center to center is i% inches. Each slat has a strip ^ inch wide 
 and X i nc h thick nailed along its length on the inside flush 
 with the bottom. The frame is in four parts and furnished with 
 screws for putting together. The bottom has one piece loose and 
 hinged, so as to allow of dropping down, and a button to hold it up. 
 Inside there is a frame for holding the thermometers, consisting of 
 two upright strips i by 3 inches fastened to long strips screwed to 
 the right and left rails of the frame with a strip i by 2^2 inches be- 
 tween the thermometers. It is painted white. This shelter should 
 be exposed upon a free grass plat where there is no obstruction to 
 the wind, and at a height of at least TO feet above the sod. An expo- 
 sure from the roof of a building is not objectionable, provided a plat- 
 form 20 feet square be first laid and the shelter be raised 8 feet 
 above the roof. The good ventilation of a roof is especially valua- 
 ble. An exposure 4 feet above sod, especially among trees, or where 
 there is very little natural ventilation, is objectionable, from the 
 fact that under such conditions radiation from the sod into space 
 abnormally cools the sod, and that in turn cools the air above it. 
 This effect is especially active at and a few hours after sunset. The 
 expense of such an exposure as that just described may deter many 
 observers from adopting it, and in such case the following substitute 
 is suggested : 
 
 WINDOW OR WALL SHELTER. 
 
 As its name implies this may be used from the iraside of a house 
 or it may be placed upon a wall and read from the outside ; in either 
 case the protection for the thermometers is the same and may be 
 very easily prepared by any one. Ordinarily a wall which should 
 invariably be one looking due north or only a few degrees to the 
 east or west of north will give too low a temperature by day, except 
 possibly in winter, and always too high a temperature by night. 
 The reason for this is not far to seek. During the daytime a large 
 wall does not gain the temperature of the free air but is nearly 
 always below it, while the reverse is true at night. 
 
 These conditions are specially prominent in the case of a large 
 brick or stone wall. The two effects above may be partly counter- 
 balanced by the following considerations : First, the effect of the 
 coolness of the wall by day may be offset by heat reflected and radi- 
 ated from other walls or surroundings; second, the warmth at night 
 may be offset in like manner by radiation to the sky. This will 
 readily suggest a form of exposure adopted by many, one very easy 
 
24 
 
 to manage, and being the least expensive of any. Select a north 
 window, preferably of an unoccupied room, especially in winter. 
 Fasten the blinds open at right angles to the wall of the house in 
 order to shield from the effects of the 'direct solar radiation on the 
 north side both morning and evening. Fasten a narrow strip, per- 
 haps 3 inches wide, across the window outside and from 8 to 12 
 inches from the window pane ; to this fasten the thermometers. 
 Some difficulty will be experienced in setting the maximum ther- 
 mometer and in wetting the wet bulb if the room is occupied, as the 
 heated air in winter will disarrange the readings of the self-regis- 
 tering thermometers. This may be partially obviated by opening 
 the upper window and conducting all operations through it. In this 
 case the heated air rises and does not affect the readings. If there is 
 no wind, or if the wind is south, the greatest disadvantage arising 
 from this exposure will be the lack of ventilation of the wet bulb. 
 This may be partly obviated by working a fan hinged near the wet 
 bulb and operated by a handle in the room. 
 
 (1) The most important consideration is as full and free natural 
 ventilation as is possible. This is essential even if an artificial ven- 
 tilation be employed for the dry and wet bulbs. Since the maximum 
 and minimum temperatures are necessarily unventilated, the shelter 
 itself should give accurate results for these. 
 
 (2) Provision should be made to avoid effects of direct solar radi- 
 ation, and also of heat reflected and radiated from surrounding 
 objects. 
 
 (3) Rain should be excluded, but only, as far as possible, in con- 
 nection with (i). During a rain-storm the dry and wet bulbs must 
 necessarily give the same values, the air being nearly saturated; 
 hence a wetting at this time is not harmful. 
 
 (4) All perraanent heating effects from warm walls, chimneys, etc., 
 should be carefully avoided. 
 
 DAILY MEAN TEMPERATURE. 
 
 The mean or average daily temperature at a place is the mean of 
 the twenty-four observations made at a place at every hour of the 
 day. Hourly observations of temperature are made at only a few 
 places over the world. Approximate values of the mean daily tem- 
 perature are obtained by various short processes. 
 
 The mean of the highest and lowest temperature of the day, as 
 observed with a maximum and minimum thermometer, gives a tem- 
 perature on the average about i.o higher throughout the year 
 than the hourly mean at places in the United States. This is the 
 mean adopted by the Weather Bureau for the observations at the 
 regular meteorological stations. In England the same mean gives 
 the temperature 0.6 of a degree too high throughout the year, being 
 1.2 too high in August and 0.3 too high in January. 
 
25 
 
 One-half the sums of the temperatures at 9 o'clock, morning and 
 evening local times, gives the mean too small by about 0.5 of a degree. 
 
 One-half the 8 o'clock, morning and evening, gives the tempera- 
 ture in the United States only a few tenths of a degree below the 
 mean of the day. 
 
 When it is possible to observe the temperature at 7 a. m., 2 p. m., 
 and 9 p. m., a very close approximation to the mean hourly tempera 
 ture of the day can be obtained by taking one fourth of the sum of 
 the temperatures at 7 a. m., 2 p. m., and twice the 9 p. m. 
 Example: 7 a. m. + 2 p. m^+ 2 (9 p. m.) 
 
 This combination is recommended where the observers can con- 
 veniently make the observations at those hours. 
 
 SOLAR RADIATION THERMOMETER. 
 
 A solar radiation thermometer consists of a mercurial thermometer 
 inclosed in a glass tube from which the air has been exhausted. 
 
 They are commonly used in pairs,-one with a black bulb, the other 
 bright, and are exposed side by side in the sun. They are known 
 as the bright and black bulb in vacuo. The black bulb will read in 
 the sunshine from 30 to 60 higher than the temperature of the air 
 in the shade. The temperature attained depends on the rate at 
 which heat is being received from the sun by the bulb and radiated 
 to the glass inclosure surrounding it, which is nearly the tempera- 
 ture of the air. 
 
 The thermometer shown in Fig. 3, is usually made as a maximum 
 with constriction in bore of stem. The inclosing bulb is about 1.5 
 inches in diameter. The highest temperature occuring during the 
 day is registered by the instrument, and it is reset each day for 
 another observation. 
 
 FIG. 3. FIG. 4. 
 
 The difference of bright and black bulb shows the difference in 
 the heating effect of the sun on the air at different times. When 
 
26 
 
 there is a great deal of moisture or dust suspended in the air more 
 of the sun's heat is absorbed in passing through it than when there 
 is very little. The more the air is heated the less the bulb. It is 
 not a good measure, however, as the difference in the bulbs depends 
 on so many things besides the clearness of the air. 
 
 The thickness of the film of blacking on the bulb affects the dif- 
 ference; also the size of the bulb the thickness of the glass bulb of 
 the inclosure, and variations in the nature of the glass not percep- 
 tible to the eye; also the depth of air through which the sun's rays 
 come. Some varieties of glass transmit more of the sun's heat than 
 others. A great deal too depends on the perfection of the vacuum. 
 The presence of the least trace of air depresses the reading. Instru- 
 ments the same to all appearances, when exposed side by side, will 
 differ as much as 6 in the temperatures indicated. 
 
 Nothing of any importance has yet been derived from observations 
 of these instruments. No way has yet been devised of making 
 different pairs comparable. 
 
 At high altitudes, as on mountain tops, the black bulb in sunshine 
 may read as high as the boiling-point of water. 
 
 In the arctic regions, in summer, the difference between the bright 
 and black is sometimes as great as 96. 
 
 The name radiation thermometer is also applied to an alcohol 
 thermometer exposed in the open air on the ground in the night 
 time to get the lowest radiation temperature of the soil. The ther- 
 mometer shown in figure 4 is the same as the ordinary minimum, 
 except that there is a--protecting glass tube over the graduations to 
 shield the graduation of the scale from the action of the dew and 
 prevent its being washed out. During the night in still air it may 
 take on a temperature 10 lower than that of the air a few feet above 
 the ground. 
 
 When a thermometer is wetted repeatedly or put in alcohol or 
 ether, the graduation becomes indistinct or illegible from the marks 
 in the etching washing out. To replace the marking, artist's black 
 pigment is used. It should be rubbed on the thermometer when the 
 tube is quite dry, and the tube then wiped with glazed paper to 
 remove the pigment not in marks. 
 
 THERMOSCOPE. 
 
 A sealed glass tube containing an alcohol solution of camphor 
 gum is sometimes used as an indicator of temperature changes. 
 When the temperature is high the camphor is all dissolved and the 
 liquid is clear. At a low temperature the camphor crystallizes out, 
 forming a fleecy whitish looking mass. A thermoscope of this kind 
 is sometimes sold mounted on the same board with a thermometer, 
 and is often erroneously supposed to indicate changes in pressure, 
 or the electrical condition of the air. 
 
27 
 
 WATER VAPOR IN AIR. 
 
 The air contains vapor of water transparent and colorless like its 
 other gaseous components. It only becomes visible on condensing 
 to fog or cloud, which is only water in a fine state of division, the 
 particles varying in diameter from 0.0006 to 0.0050 of an inch. The 
 amount is very variable at different times, even in the vicinity of 
 the ocean, depending mainly on the temperature of the air. On 
 very cold days it forms no more than the one-thousandth part of the 
 air. On very warm days it may be as great as one-fiftieth part. 
 
 The amount of moisture chat can exist as vapor in the air depends 
 on the temperature. There is a certain pressure of vapor corre- 
 sponding to every temperature which cannot be exceeded ; beyond 
 this there is condensation. This temperature is called the tem- 
 perature of saturation for the pressure. When the temperature of 
 the air diminishes until the saturation temperature for the vapor con- 
 tained is reached, any further fall causes a condensation of moisture. 
 
 The temperature at which this occurs at any time is called the 
 dew-point temperature of the air at that time. The less the quantity 
 of moisure the air contains the lower will be the temperature of its 
 dew point. 
 
 This property of vapor is made use of to determine the pressure 
 of vapor contained in the air at any time. The number of degrees 
 the dew point is below the temperature of the air is called the 
 depression of the dew point. 
 
 The relation of water- vapor pressure and temperature has been 
 very thoroughly investigated by skillful experimenters on account 
 of its importance in the theory of the steam engine. 
 
 For different saturation temperatures the vapor pressures, in 
 inches of mercury, and the weight of vapor, in grains, contained in a 
 cubic foot of air are as follows : 
 
 Temperature Vapor pres- Weight in a 
 
 of satura- sure in cubic foot, 
 
 tion. inches. grains. 
 
 0. 038 0. 56 
 
 10 0. 063 0. 87 
 
 20 0. 103 1. 32 
 
 30 0. 164 1. 96 
 
 40 0. 246 2. 85 
 
 50 0. 360 4. 08 
 
 60 0. 517 5. 74 
 
 70 0.732 7.98 
 
 80 1.022 10.93 
 
 90 1. 408 14. 79 
 
 100 1. 916 19. 77 
 
 The quantity of water contained in the air is nearly proportional 
 to the vapor pressure. The air is never perfectly saturated, not 
 even when rain is falling ; neither is it ever perfectly dry at any 
 place. 
 
 The number expressing the vapor pressure in the air at any time 
 divided by the number expressing the pressure of saturation for the 
 
28 
 
 temperature prevailing at the time is the fraction of saturation, and 
 is called the relative humidity. It is expressed in hundredths of 
 the pressure at saturation and is called percentage of relative 
 humidity. With the air at a temperature of 60, for instance, if the 
 pressure of vapor contained is found to be 0.420 of an inch, the 
 pressure at that temperature for saturation being 0.5 17, the percent- 
 age of relative humidity is the one divided by the other, expressed 
 in hundredths as the unit, or 81 per cent. 
 
 Relative humidity expresses relative amount of moisture in the 
 air only as long as the temperature of the air remains constant. 
 For this reason relative humidity is an imperfect datum. At a low 
 temperature even a high relative humidity represents a very small 
 amount of vapor actually in the air, while a low relative humidity 
 at a high temperature represents a great deal. At a temperature 
 of 30, for instance, a relative humidity of 90 per cent, corresponds 
 to 0.149 f an i nc h vapor pressure, while 50 per cent, at 80 corre- 
 sponds to a pressure of 0.511, or more than three times as much as is 
 contained at the temperature of 30. 
 
 The amount of moisture in the air is ascertained indirectly by 
 observing the temperature at which dew is deposited, or by deter- 
 mining the vapor pressure by means of the difference in indication 
 of a dry and wet bulb thermometer. 
 
 PSYCHROMETER. 
 
 Two thermometers, one with wet and the other with dry bulb, 
 when used to determine the vapor pressure in the air, is called a 
 psychrometer. The wet bulb consists of an ordinary mercurial 
 thermometer with a wrapping of muslin on the bulb kept saturated 
 with water. The water evaporating from the muslin cools the bulb. 
 The dryer the air the greater the amount of evaporation and the 
 more the bulb is cooled, and consequently the reading of wet bulb 
 is lower the dryer the air. 
 
 From a series of comparisons of the indications of a dew-point 
 apparatus and a psychrometer the relation between the pressure of 
 the vapor in the air and its dependence on the difference between 
 the reading of the dry and wet bulb thermometer has been ascer- 
 tained. Tables showing this relation are given here. With the differ- 
 ence of dry and wet bulb and the temperature of the air, the reading 
 of the dry bulb, the temperature of dew point of the air is obtained 
 from one table and the relative humidity from the other. 
 
 The result found for vapor pressure with a psychrometer varies a 
 little in still air, depending on whether the wet bulb is spherical or 
 cylindrical. It also depends on the absolute size of the bulb and 
 whether the stem above the bulb for an inch or so is wrapped with 
 the wet muslin. All of these effects are obviated by whirling the 
 psychrometer so as to cause a brisk renewal of air around the bulb. 
 
29 
 
 When whirled before making the readings, instruments of the most 
 diverse patterns are strictly comparable.. 
 
 Where the highest accuracy is required the most minute correc- 
 tions of the thermometers have to be applied. Small errors in the 
 observed temperatures affect the deduced vapor pressures very much. 
 The tables given are based on psychrometer readings uncorrected 
 for the difference of temperature between the bulb of the wet ther- 
 mometer and its stem, the stem being at the temperature of the air 
 while the bulb is a variable number of degrees lower, depending on 
 the dryness of the air. For a long stem this correction may amount 
 to 0.3 or 0.4 of a degree. 
 
 SLING PSYCHROMETER. 
 
 For values of dry and wet bulb temperatures the most accurate 
 method yet devised consists in the use of dry and wet bulb ther- 
 mometers fastened together and whirled quite rapidly. Any one 
 may very readily prepare this instrument. The thermometers may 
 be fastened back to back or side by side, the wet bulb an inch or so 
 lower than the dry; then a rather strong wire or a good many folds 
 of a thinner one should be passed through the hole at the top of the 
 scale, and to this a stout cord about 12 inches long should be fastened. 
 A glove finger will serve to protect the finger while whirling. The 
 method of use is very simple. First wet the muslin by immersion 
 and wait about a minute till the wet bulb has fallen somewhat (this 
 is specially necessary in a very dry air, as otherwise the muslin may 
 become dry before it has reached its lowest reading), then whirl the 
 thermometers about 50 times, stop and read the wet bulb, then whirl 
 20 times and again read. If the temperature of the wet bulb has not 
 changed it may be considered as the correct value. If there has been 
 a change to a lower reading continue the alternate whirling and 
 reading until the wet bulb reaches its lowest reading or one slightly 
 higher than the one previous. The lowest reading is to be recorded. 
 A velocity of 12 feet per second is ample. 
 
 Great care should be taken never to allow the muslin to become 
 dry or even partly so. At night the whirling may be done at any 
 convenient spot where there is a good ventilation. The temperature 
 should be taken at least 6 feet above sod or at any height greater 
 than that. If there is a wind blowing the observer should stand to 
 leeward; if there is no wind, in cool weather, it may be necessary to 
 walk about while whirling in order to overcome any possible vitiation 
 of the reading from the heat of the body. When the sun is shining, in 
 the daytime, the temperature should be taken in the shade of a 
 small object, high tree, or even umbrella, but not in the shade of a 
 wall or large house. The use of this instrument when the wet bulb 
 is covered with ice is specially satisfactory. The lowest reading at 
 any time may be obtained in three minutes, while with a rather 
 
30 
 
 close window shelter, when the air is still, it will require a delay of 
 an hour tor even an approximate value. 
 
 HAIR HYGROMETER. 
 
 A human hair when freed of oil, by soaking in ether for twenty- 
 four hours, has the property of changing by about one-thirtieth part 
 of its length between a very dry and very moist condition of the hair 
 at ordinary temperatures. 
 
 A hair hygrometer consists of a hair about 12 inches in length 
 mounted in a brass frame, the lower end wound once around a pulley 
 and stretched by a weight of about i gramme, or 15.4 grains Troy. 
 
 As the pulley turns with the varying length of hair dependent on 
 the dryness of the air, an attached index moves over a graduated arc, 
 indicating the percentage of humidity or relative humidity. It is 
 graduated with reference to a dew-point apparatus or a psychrometer. 
 It is not an accurate instrument, its results being complicated with 
 changes of temperature. It is only used in closed spaces where 
 other means of observing vapor pressure are not available. It gives 
 a rough result very quickly. It is sometimes used for humidity ob- 
 servations at temperatures below zero. 
 
 BAROMETER. 
 
 The air presses on everything at the surface of the earth with a 
 pressure equal to the weight of the column of air above it to the 
 limit of the atmosphere. This pressure is on the average about 14.67 
 pounds to the square inch, and corresponds to the pressure of a 
 column of mercury about 30 inches in height. The pressure of the 
 air is continually varying within small limits. Variations in pres- 
 sure are not noticeable to the senses except in the case of sudden 
 great changes. 
 
 The barometer is an instrument used to measure the pressure of 
 the air. Pressures are expressed in the equivalent height of a 
 column of mercury reduced to the temperature of freezing point. 
 
 The barometer is a glass tube open at one end and closed at the 
 other, about 38 inches long and % inch in interior diameter. The 
 open end dips into the cistern of the instrument containing mer- 
 cury which extends inside the tube up to a height corresponding 
 to the pressure of the air. The tube above the column of 
 mercury contains no air. The vertical height of the level 
 of the top of mercury column above the level of mercury in 
 the cistern, in inches and parts of an inch, is called the barometer 
 reading. This height is constantly varying within small limits with 
 the changing pressure of the air. 
 
 The barometer is first set up by the maker by filling the tube 
 with mercury and inverting it with the open end immersed in the 
 mercury in the cistern, the end being closed temporarily with the 
 gloved finger until it is immersed in the mercury. When the finger 
 
31 
 
 a 
 
 is removed the mercury runs down the tube, oscillating back and 
 ferth and finally coming to rest at a height corresponding to the 
 pressure of the air outside. 
 
 The observation of pressure consists in ascertaining the height of 
 column at any time by means of the scale attatched to the instru- 
 ment. For this purpose an ivory point, the lower extremity of 
 which is the zero of the scale, is fixed to the frame-work of the 
 instrument, on the upper portion of which is the graduated scale 
 and vernier. The mercury in the cistern is brought in contact with 
 the ivory point and the vernier of the scale is adjusted to the top of 
 the column ; the reading of the scale will then give the height of 
 the column of mercury. 
 
 Placing. The barometer should be placed in a room of a tempera- 
 ture as uniform as possible, and not exposed to the sun. It must 
 be suspended so that the top of the column will be at the height of 
 the eye, near a window, in such a manner as to be lighted perfectly 
 without exposure either to the direct rays of the sun or to the cur- 
 rents of the air which are always to be found at the joinings of the 
 windows. When the barometer has to be fixed to the wall, as is the 
 case with all the self-recording and some other 
 barometers, care must be taken to secure the tube 
 ( in a position perfectly vertical, regulating it by the 
 plumb-line, first in the front, then at the sides, in 
 two vertical planes cutting each other at right angles. 
 When the instrument is so constructed as to take 
 its equilibrium itself, as the Fortin barometers and 
 those of J. Green, it is enough to hang it on a strong 
 hook. These conditions being fulfilled, the rest of 
 the arrangement may be varied according to the 
 nature of the localities. For the Fortin and Green 
 barometers the following arrangement is convenient, 
 and may be almost everywhere adopted. (See Fig. 5.) 
 A small elongated box (a b), some inches longer than 
 the barometer and a little broader than its cistern, is 
 firmly set against the wall (w w'), near the window, 
 in such a manner as to open in a direction parallel 
 to the panes ; at the summit (a) it has a strong hook 
 (h /$'), which extends beyond the box about 2 or 3 
 inches, and on which the barometer is suspended. 
 The instrument remains generally in the box, which 
 is closed by a movable cover, and which protects it 
 from external injuries, from dust, and from the direct 
 radiation of warm bodies, or the currents of air from 
 F 5 the window, and diminishes the effect of the too 
 
 sudderfvari-ations of temperature. When it is to be observed, the 
 barometer is taken by the upper end of the tube, and the suspending 
 
32 
 
 ring- is made to slide toward the end of the hook. The instrument 
 is then in the full light of the window, in front of which the observer 
 places himself ; the summit of the mercurial column, as well as the 
 surface of the mercury in the cistern, are completely lighted, and 
 the reading becomes easy and certain. Moreover, the slight oscillat- 
 ing movement impressed on the instrument by changing its place 
 breaks the adherence of the mercury to the glass, and thus prepares 
 a good observation. After the reading, the barometer is again 
 slipped gently into the box, and this is closed. 
 
 It has been found that even with the exercise of care the barom- 
 eter cistern strikes against the box when it is pushed in, and in con- 
 sequence the instrument deteroriates quite rapidly. To avoid all 
 possibility of injury from this cause it is only necessary to make two 
 oblong sets of openings in the back of the box, one just at the ivory 
 point about 3 inches long, and the other at the vernier some 8 inches 
 long, and place in these plates of glass. If now the barometer box 
 be suspended vertically in a north window it will be a very simple 
 matter to make readings by opening the box and adjusting the 
 mercury to the ivory point and the vernier to the top of the 
 column, without moving the barometer. 
 
 Observation. Note the degree and the tenths of degrees of the 
 thermometer attached to the instrument; for it will be seen that the 
 heat of the observer's body soon makes it rise. 
 
 Incline the instrument gently, so as to render the mercurial column 
 very movable; then, after having restored it to rest, strike several 
 slight blows upon the casing, in such a manner as to impress on the 
 mercury gentle vibrations. The adherence of the mercury to the 
 glass will thus be destroyed, and the column will take its true 
 height corresponding to the outside pressure of the air. 
 
 Bring, by means of the adjusting screw at the bottom, the surface 
 of the mercury to the zero of the scale. 
 
 In the barometers with an ivory point, as the Fortin, Newman, 
 and Green barometers, the extremity of this point is the zero of the 
 scale, which must be brought into exact contact with the surface of 
 the mercury. This takes place when the point coincides exactly 
 with its image reflected below by the mercury. This method is very 
 good when the surface of the mercury is perfectly pure and brilliant. 
 It is generally dimmed by a slight layer of oxide, which makes the 
 coincidence of the point with its image uncertain. It is safer to 
 judge of the contact in a different manner. From the moment when 
 the point does more than touch the surface, it forms around itself, 
 by capillary action, a small depression, which, breaking the direction 
 of the reflected rays, becomes immediately very easy to discover. 
 It is enough, then, to raise the mercury so as slightly to immerse the 
 point; then to lower it gradually iintil the little depression dis- 
 appears. If care is taken to make a good light fall on that portion 
 
33 
 
 of the mercury which is under the point, and to use the aid of a 
 magnifier, the adjustment of the point thus made becomes not only 
 easy, but very certain, and the errors to which we are liable are 
 almost insensible, for they do not exceed two or three hundredths 
 of a millimeter, or a thousandth of an inch. 
 
 The level being thus adjusted to the zero of the scale, proceed to 
 observe the height of the summit of the column. Take hold of the 
 instrument with the left hand, above the attached thermometer, 
 without moving it from the vertical; tap it gently in the neighbor- 
 hood of the top of the column; then, by means of the screw, lower 
 the slide which carries the vernier, until the plane passing through 
 the two lower opposite edges of it is exactly tangent to the summit 
 of the meniscus that is, the convexity which terminates the column. 
 This is the case when, placing the eye exactly at the height of the 
 summit of the column, it is seen without there being any trace of 
 light between the summit and the edge of the ring. To be certain 
 that the barometer has remained quite vertical during its operation, 
 leave it to itself, and, when it is at rest, look again to see whether the 
 ring has remained tangential to the summit of the column. If it 
 has not, the verticality has been disturbed; it must be adjusted 
 anew. It is necessary, at the same time, to examine if the adjust- 
 ment of the surface of the mercury in the cistern has remained the 
 same. 
 
 Nothing more, then, remains than to read the instrument. In the 
 English barometers the inches and tenths of inches are read directly 
 on the scale, the hundredths and thousandths on the vernier. In 
 the French barometers, with the metrical scale, the centimeters and 
 millimeters are read on the scale, and the fractions of millimeters 
 on the vernier. 
 
 THE VERNIER. 
 
 The vernier is a contrivance for measuring fractional portions of 
 one of the equal spaces into which a scale or, as commonly known, 
 a limb is divided. We will call the fixed portion of the barometer, 
 which is divided into equal parts, the scale, and the part which 
 moves upon it by means of the screw and ratchet, the vernier. A 
 simple inspection will indicate the nature of the spaces or equal 
 parts of the scale. In the common barometer there are inches and 
 tenths, or centimeters and millimeters. Ordinarily the spaces on 
 the whole length of the vernier are one more than on the part of the 
 scale which it covers : /. <?., if the vernier has ten spaces the scale 
 has nine in the same length. Determine the value of the smallest 
 space on the scale (in the common Green barometer this is one- 
 tenth inch), divide this by the number of spaces on the vernier, and 
 we get immediately the least count of the vernier. We have then the 
 following rule : The least count of a vernier is equal to one of the 
 
34 
 
 spaces of the scale divided by the number of equal parts on the 
 vernier. 
 
 The reading of the instrument depends on the distance from the 
 zero point or the beginning of the scale to the zero point of the 
 vernier. If we take a vernier and make its zero point coincide with 
 one of the divisions on the scale we shall find the second line exactly 
 the least count of the vernier below the second line of the scale; or, 
 in other words, if we move the vernier until its second line coincides 
 with the one just above the first line on the scale, just referred to, 
 we shall move the zero just the least count above its first position. 
 In the same way the zero of the vernier may be made to coincide 
 with other divisions on the limb, and the distance moved will depend 
 on the number of the line on the vernier above its zero which is 
 coincident with the line on the scale. We have then the simple rule 
 for reading a vernier. Read the scale up from its zero, or in the 
 direction in which the figures on the graduations increase up to that 
 line of the scale just below the zero of the vernier. Call this the 
 reading of the scale. Find the number of the line on the vernier, 
 counting the first line above the zero as i, which coincides most 
 nearly with aline on the scale; multiply the least count of the vernier 
 by this number; this will give the reading on the vernier; the sum 
 of these two readings is the reading of the instrument. 
 
 The observer is advised to test his ability to read the vernier by 
 setting it at various points and then reading. After a time one 
 reads the vernier naturally, without being obliged to follow any 
 fixed rules. It will seldom occur that a line on the vernier exactly 
 coincides with one on the scale, and after a little practice one will 
 be able readily to split the least count; for example, if any two con- 
 tiguous lines of the vernier lie between and exactly equidistant from 
 two on the scale, the least count will be exactly halved. It is a very 
 good plan, in order to avoid serious mistakes, at first to estimate the 
 position of the zero line of the vernier on the scale; this will give 
 the approximate value of the reading and will check the reading 
 made from the vernier. 
 
 To read the vernier, we must look out for the line that coincides 
 with one of the divisions of the scale. The number of this division 
 of the vernier, proceeding from zero, indicates the number of tenths 
 of millimeters, or of hundredths of an inch, which must be added to 
 the whole number given by the scale. If none of the divisions of 
 the scale coincides exactly, we estimate by the eye, in decimals, the 
 quantity by which the vernier must be lowered to obtain a coinci- 
 dence, and this is added to the fraction already obtained. This will 
 be hundreths of millimeters in the metrical barometer, and thou- 
 sandths of inches in the English barometers. 
 
 The following figures will serve as examples; the instrument is 
 an English barometer: 
 
35 
 
 In Fig. 6 the regulating line, which is the lower edge of the vernier 
 ring, coincides exactly with the line of 30 inches on the scale. The 
 zero and the tenth division of the vernier are also in exact coinci- 
 dence; that is to say, there is no fraction. We shall read then 30.000 
 inches. 
 
 In Fig. 7 the regulating line does not fall upon any of the divisions 
 of the scale, but between 2 9l % and 29-^- inches. There is then a 
 fraction which must be read on the vernier. Seeking which of these 
 divisions coincides with that of the scale, we find that it is the fifth; 
 we shall write then 29.250 inches. 
 
 -10 
 
 -10 
 
 80- 
 
 FIG. 6. 
 
 FIG. 7. 
 
 FIG. 8. 
 
 In Fig. 8 we see that the height falls between 30 inches and 
 inches; no line of the vernier coincides exactly; but the line 7 is a 
 little above, the line 8 is a little below, one of the lines of the scale; 
 the fraction falls, then, between seven and eight hundredths. Esti- 
 mating in tenths the distance the vernier passes over between the 
 coincidence of 7 and that of 8, the tenths of a hundredth, or the 
 thousandths are obtained. In the latter case the distance above 7 is 
 greater than the half; it will read then, greater than 30.075 and 
 less than 30.080, or about 30.077. It will always be easy to judge 
 whether the top approaches nearer the upper coincidence than 
 the lower coincidence; in the former case the fraction is greater 
 than .005; in the latter it is smaller than .005. The error which will 
 be committed in this estimate will remain less than .005; after 
 a little practice it will rarely exceed .002, always supposing the scale 
 is well graduated. For this reading, as well as for the others, it 
 is particularly important to have the eye exactly at the height of 
 
 the line to be determined. 
 9377 3 
 
36 
 
 During the whole time of the observation of the barometer the 
 observer must endeavor to protect it as much as possible from the 
 heat which radiates from his body. But the best way is to learn to 
 observe rapidly. All the operations take longer to describe than to 
 execute; one or two minutes, if the instrument be in place, three 
 minutes, if it is to be taken from its case and put back again, are 
 sufficient for a practiced observer to make a good observation. 
 
 The barometer consists of a brass tube (Fig. 9) terminating at 
 top in a ring A, for suspension, and at bottom in a flange B, to which 
 the several parts forming the cistern are attached. 
 
 The upper part of this tube is cut through so as to expose the glass 
 tube and mercurial column within, as seen in figure. Attached at 
 one side of this opening is a scale, graduated in inches and parts; 
 and inside this slides a short tube C, connected to a rackwork 
 arrangement, moved by a milled head D; this sliding tube carries 
 a vernier in contact with the scale, which reads off to ^ (.002) of 
 an inch. 
 
 In the middle of the brass tube is fixed the thermometer E, the 
 bulb of which being externally covered, but inwardly open, and 
 nearly in contact with the glass tube, indicates the temperature of 
 the mercury in the barometer tube, not that of the external air. This 
 central position of the thermometer is selected that the mean tem- 
 perature of the whole column may be obtained, a matter of im- 
 portance, as the temperature of the barometric column must be taken 
 into account in every scientific application of its observed height- 
 
 The cistern (Fig. 10) is made up of a glass cylinder F, which allows 
 the surface of the mercury q to be seen, and a top plate G, through 
 the neck of which the barometer tube / passes, and to which it is 
 fastened by a piece of kid leather, making a strong but flexible 
 joint. To this plate, also, is attached a small ivory point //, the 
 extremity of which marks the commencement or zero of the scale 
 above. The lower part, containing the mercury, in which the end 
 of the barometer-tube / is plunged, is formed of two parts / /, held 
 together by four screws and two divided rings / ;;/, in the manner 
 shown in figure. To the lower piece j is fastened the flexible bag 
 N, made of kid leather, furnished in the middle with a socket /, 
 which rests on the end of the adjusting screw O. These parts, with 
 the glass cylinder F, are clamped to the flange B by means of four 
 long screws P and the ring R; on the ring R screws the cap S, which 
 covers the lower parts of the cistern, and supports at the end the 
 adjusting screw O. G, i,j, and k are of boxwood; the other parts are 
 of brass or German silver. The screw O serves to adjust the mercury 
 to the ivory point, and also, by raising the bag, so as to completely 
 fill the cistern and tube with mercury, to put the instrument in con- 
 dition for transportation. 
 
 Some cisterns are made of an iron or glass cylinder with a 
 plunger working in it air-tight. 
 
37 
 
 FIG. 9. 
 
 FIG. 10. 
 
38 
 
 CORRECTION OF BAROMETRIC OBSERVATIONS. 
 
 Corrections must be applied to all barometer readings in order 
 to bring the indications of different instruments into harmony with 
 each other before they can be used for comparative purposes. Some of 
 these corrections have reference to the special instrument, while 
 others are applied to the reading of any instrument taken under the 
 same conditions. The corrections of the former class are two in 
 number: 
 
 I. Instrumental error. 
 II. Capillarity. 
 
 Those of the latter class are also two: 
 III. Temperature. 
 IV. Altitude above sea level. 
 
 I. Correction for instrumental error. This is applied according to 
 the error discovered in the individual instrument when compared 
 with the standard. It is either additive ( + ) if the barometer reads 
 too low, or subtractive ( ) if it reads too high, in order to bring it 
 into agreement with standard. 
 
 II. Correction for capillarity. The indications of barometers are 
 affected by the capillary action between the glass tube and the mer- 
 cury, the effect of which is constantly to depress the mercury by a 
 certain quantity nearly inversely proportional to the diameter of 
 the tube. This correction is included in the correction for instru- 
 mental error. 
 
 The correction is always additive. 
 
 This depression is greater in tubes in which the mercury has not 
 been boiled than in those which have been subjected to this process. 
 
 The certificates furnished from the Weather Bureau Office for all 
 barometers verified there give the results of direct readings of the 
 columns at different heights, and so include the corrections above 
 mentioned, in so far as any of them are applicable to the special 
 barometer under consideration. 
 
 Correction for temperature, or reduction (032 F. All bodies are affected 
 in their dimensions by heat; with few exceptions they expand when 
 their temperature rises and contract when it falls, and it is there- 
 fore necessary, in taking any accurate measure of pressure, to know 
 at what temperature it was taken, in order that we may know what 
 the length of the column of mercury would be at some definite 
 temperature, which is taken as the standard. In case of barometers 
 this standard temperature is taken as 32, and accordingly when 
 the barometer is at a temperature below 32, considering only the 
 mercurial column, the correction is additive ( + ), and when it is 
 above 32 it is subtractive ( ). 
 
 If the standard temperature for the brass scale were the same as 
 that used for mercury, the sign of this correction would change from 
 
39 
 
 + to at 32, but the standard temperature for the scale is regarded 
 as 62; hence the sign changes at 29 instead of 32, the total cor- 
 rection being the difference of the two corrections, one for the 
 temperature of the mercury and the other for the temperature of 
 the scale. The expansion of the mercury is about ten times as great 
 as that of the scale. 
 
 The temperature of the barometer is given by the attached ther- 
 mometer, the bulb of which is so placed as to give as accurately as 
 possible the true temperature of the actual column of mercury. 
 
 The corrections are given in the table for each half inch from 24 to 
 31 inches, as of course the correction depends on the length of the 
 column of mercury. 
 
 In consequence of the great risk of the heat of the observer's person 
 affecting the thermometer attached to the instrument during the 
 process of taking a reading of the barometer, the attached thermom- 
 eter is always to be read first of all, before the reading of the baro- 
 metrical column is made. 
 
 The table at the end of these instructions contains the corrections 
 to be applied to the readings of barometers mounted in brass frames, 
 in order to reduce them to the normal temperature, 32. It has been 
 computed from the following formula: 
 
 T m(*-32) s-62) 
 Corrects -ft-^-^-i^- 
 
 ill which 
 
 7t=reading of the barometer, 
 
 <=temperature of attached thermometer, 
 
 w=rexpansion of mercury for 1 F., taken as .0001010 of its length at 32, 
 
 s=expansion of the substance of which the scale is made ; for brass is taken 
 
 as .00001020 of its length (/t) at the standard temperature for the scale* 
 
 viz: 62 F. 
 
 CORRECTION FOR ALTITUDE OR REDUCTION TO SEA LEVEL. 
 
 As we ascend in the atmosphere the pressure gradually diminishes- 
 At the height of Pike's Peak, 14,134 feet above sea level, the mean 
 pressure is about 17.8 inches. At sea level it is 30.0 inches.* In 
 order then to make barometer readings comparable at different 
 stations it is necessary to reduce them to a common plane. This 
 is taken as sea level. This reduction depends upon the temper- 
 ature of the outside air as well as the height of the station. It is 
 important that each observer obtain as accurately as possible 
 the elevation of his barometer, first, above a fixed point near its place 
 
 *A convenient rule for finding the difference of level between two places by means 
 of barometer observations is as follows: The difference of level in feet is equal to the 
 difference in pressures at the two places divided by the sum of the pressures and mul- 
 tiplied by the number 55761 for a mean temperature of the air at the places equal to 
 60 ; for every degree the temperature is greater than 60 the number is 117 greater, 
 and for every degree below 60 it is 117 less. For example, with the observed pres- 
 sure of 29.0 inches at a height and 30.0 inches below with the air temperature 60, 
 the difference of level between the two places is, ^ X 55761 = 945 feet. 
 
40 
 
 of suspension ; second, the elevation of the fixed point above some 
 plane, such as a railroad track at station, bench-mark on canal, or 
 zero of river gauge, the height of which above sea level is known. 
 The sum of these three quantities will give the elevation of the 
 barometer above sea level. If it is found impossible to get the 
 correct elevation in this way, an approximate value may be com- 
 puted by means of barometric observations at the station, com- 
 pared with those made at the same time at a neighboring station, 
 the elevation of which is known. As a general thing, however, 
 it will be found feasible to obtain the elevation from a railroad track 
 near the station. Table VII at the end of these instructions will 
 give the reduction for barometer readings at stations up to 1,500 
 feet. For greater heights the pressure at sea level may be com- 
 puted from the following formula: 
 
 From a table of common logarithms, the natural number corresponding to log l f is 
 found; OT =n, and h=nli / 
 
 In this formula 
 h and /j/=barometer reduced to 32 F., at sea level and upper station, respect- 
 
 ively, 
 
 t and < / =the temperature of the air at the respective stations, 
 /^elevation of upper station in feet, 
 Platitude of the place. 
 
 Barometers are standardized by suspending them near a correct 
 standard barometer and shifting the scale until its reading coincides 
 exactly with the standard or its correction is derived to reduce to 
 the standard. The instrument is hung with lower end free. If the 
 lower end is fixed for convenience in adjusting the mercury in cis- 
 tern to the ivory point, care must be taken to fasten it without 
 changing the verticality of the tube. Any changes in the suspend- 
 ing ring, putting on a heavier attached thermometer, or shifting the 
 ivory point in cistern, is apt to throw the instrument out of adjust- 
 ment and cause its readings to be erroneous by several hundredths 
 of an inch. 
 
 To make pressure observations at different latitudes strictly com- 
 parable, a correction must be introduced for the variation in the 
 force of gravity on the different parallels from the equator to the 
 poles. The reduction is made to the latitude of 45 and sea level- 
 At latitude 30 the correction amounts to 0.039 f an inch; at 70 
 to -j- 0.060. 
 
 Pressures can be observed accurately with a mercurial barometer 
 of one-quarter inch bore to about 0.006 of an inch. For more 
 accurate pressures a tube a half inch or inch in diameter is required 
 with a very elaborate apparatus called a cathetometer, for measur- 
 ing the difference in level of the surfaces of mercury in cistern and 
 
41 
 
 ANEROID BAROMETER. 
 
 Fig. ii represents the latest improved form of an aneroid. The 
 outer casing and face of the instrument are removed, but the 
 index hand is left attached to the arbor. A is the corrugated 
 vacuum box which has been exhausted of air through the tube / 
 and hermetically sealed by soldering. is a powerful curved spring 
 resting in gudgeons fixed on the base plate, and attached to a 
 
 socket behind F, in the top of the 
 vacuum box. A lever, C, joined to 
 the stout edge of the spring, is con- 
 nected by the bent lever at Z>, with 
 the chain , the other end of which 
 is coiled round and fastened to the 
 arbor F. As the box A is compressed 
 by the weight of the atmosphere 
 increasing, the spring^, is tightened, 
 the lever C depressed, and the chain 
 FIG. 11. E uncoiled from F which is thereby 
 
 turned so that the hand If moves to the right. In the meanwhile 
 the spiral spring G coiled round F, and fixed at one extremity to the 
 frame work, and by the other to F, is compressed. When, therefore, 
 the pressure decreases, A and B relax by virtue of their elasticity; 
 E slackens, G unwinds, turning F, which carries the index hand If 
 to the left. Near J is shown an iron pillar, cast as part of the stock 
 of the spring^. A screw works in this pillar through the bottom of 
 the plate, by means of which the spring B may be so adjusted to the 
 box A as to set the index H to read on the scale in accordance with 
 the indications of a mercurial barometer. In the higher class of 
 aneroid barometers the lever Cis formed of a compound bar of brass 
 and steel, so arranged as to compensate for the effects of extreme vari- 
 ations of temperature. A very small movement of the surface of the 
 vacuum chamber causes a large deviation of the needle end, Q of 
 an inch causing it to move through a space of 3 inches. 
 
 Aneroids have to be graduated with reference to a mercurial 
 barometer. 
 
 The elasticity of a spring varies with temperature. A given weight; 
 will pull down a spring more at a high temperature than a low one. 
 This causes an aneroid to read too high with temperature. In the 
 best forms of aneroid there is an attempt made to compensate for 
 temperature, by making one of the transmitting levers a compound 
 of two metals, a strip of steel and brass soldered lengthwise. An 
 accurate compensation is only rarely accomplished in this way, and 
 when it is accomplished, in the case of some instruments, it is a mere 
 accident. To get correct pressures every instrument must be 
 investigated and corrections for different pressures and temper- 
 atures derived. A change of 20 in the temperature of the 
 
42 
 
 instrument will often change the pressure indication one-tenth of 
 an inch, in some instruments one way and in others the opposite, 
 without any actual change going on in the pressure of the air. 
 
 A compensation is sometimes attempted by leaving some air in 
 the box. As the spring weakens at a high temperature the increas- 
 ing pressure of the air inside the box, due to the higher temperature, 
 counterbalances the effect on the spring to some extent. This 
 method of compensation is usually ineffective. 
 
 Aneroid barometers do not require a gravity correction, the ten- 
 sion of a spring not varying with latitude. 
 
 The spring of an aneroid barometer changes with age and with 
 extreme variations of pressure causing its indications to vary inde- 
 pendently of variations in the pressure, of the atmosphere. There 
 is a continual rise in the indicated pressures with age of the instru- 
 ment, amounting, usually, to 0.08 of an inch in three years. After 
 subjection to a low pressure, as in a mountain ascent, an aneroid 
 does not recover its original reading at once when restored to 
 ordinary pressures. After lowering to a pressure of 18 inches its 
 reading will be 0.3 of an inch lower than it was before when brought 
 back to a pressure of 30 inches. The original reading is recovered 
 in a few weeks. 
 
 An aneroid requires constant control and adjustment by reference 
 to a mercurial barometer. It is not as accurate or satisfactory for 
 making pressure observations as a mercurial instrument. Shocks 
 and jars are liable to derange it. On account, however, of its conve- 
 nience, the ease with which it can be carried over rough country 
 where a mercurial barometer would be liable to be broken, the 
 aneroid is used a good deal in making observations of pressure, 
 especially for approximate determinations of altitude. An aneroid 
 is rarely used in meteorological observations, usually only when a 
 mercurial barometer is out of order and until another one can be 
 procured. 
 
 The words "fair," "stormy," "rain," etc., sometimes on the dial 
 of an aneroid have no real significance as regards weather, being 
 simply a device intended to help the sale of the instruments. 
 
 HYPSOMETER. 
 
 The temperature of boiling water is lower, the lower the pressure 
 of the air. The boiling point at a standard pressure of 29.922 inches 
 is 2i2.o; at a pressure of 18.0 inches it is i87 .5. This fact is made 
 use of at times in determining pressures, especially for the deter- 
 mination of altitudes in mountain ascents. 
 
 A thermometer with its boiling point apparatus when used for the 
 purpose of determining pressures is called a hypsometer. The ther- 
 mometer is made short, only about 6 inches in length, for convenience 
 in carrying, and is graduated only from about 170 to 214. The 
 best form of thermometer for this purpose has two or three degrees 
 
43 
 
 in the vicinity of freezing point graduated on the stem to permit of 
 observations of the variation of the freezing point. An inconvenient 
 length of stem is avoided by means of an enlargement in the bore 
 of the stem, between freezing point and the graduation of 170, in 
 order to hold the mercury. 
 
 The pressure observed with a hypsometer can be made with an 
 accuracy of about 0.06 of an inch. 
 
 READING INSTRUMENTS. 
 
 In reading thermometers or barometers, it is essential to bring the 
 eye so that the line from the eye to the end of the column shall be 
 horizontal. This is most important in case the thermometer is 
 graduated only on the brass scale behind the tube, as a little varia- 
 tion in the position of the eye above or below the line of graduation 
 will make a large difference in the reading. Care should be taken 
 in the reading to note correctly the number of degrees that the 
 thermometer indicates. It has been found that frequently errors of 
 5 creep in from a want of care in this respect. A little practice will 
 enable any one to split the degree into tenths ; /. e. t to regard the 
 space as divided into ten equal parts and to take the nearest tenth 
 that the instrument indicates for record. 
 
 RAIN GAUGE. 
 
 Rainfall is measured as the depth of water it would form on the 
 ground were it to remain as it falls. In the case of snow its depth 
 is measured as the depth of water it would form if melted. Rain, 
 hail, and snow are known under the general designation of precipi- 
 tation. 
 
 Snowfall is preferably measured as depth of water rather than by 
 the thickness of layer it forms on the ground. When it is not con- 
 venient to measure it by melting, it is customary to take it as one- 
 tenth of the measured depth of the snow on a level open place. The 
 relation between the depth of snow and depth of melted snow is 
 very different in different cases, depending on the wetness of the 
 snow. The equivalent depth of water in some cases is as great as 
 one-seventh of the depth of snow and in others only one thirty- 
 fourth. It is always best to melt it for measurement. 
 
 Rain-gauges in slightly different positions differ greatly in the 
 depth of rain indicated. Within a few yards of each other two 
 gauges may show a difference of 20 per cent, in the rainfall in a 
 heavy rainstorm. The stronger the wind the greater the difference 
 is apt to be. In a high location eddies of wind produced by walls 
 of buildings divert rain that would otherwise fall in the gauge. A 
 gauge near the edge of the roof, on the windward side of a building, 
 shows a less rainfall than one in the center of the roof. The verti- 
 cal ascending current along the side of the wall extends slightly 
 above the level of the roof, and part of the rain is carried away from 
 the gauge. 
 
44 
 
 In the center of a large flat roof, at least 60 feet square, the rain- 
 fall collected by a gauge does not differ materially from what is 
 collected at the level of the ground. 
 
 A rain-gauge mounted on a mast at a height of 43 feet collects 
 only 0.75 as much as at the ground ; at 85 feet, only 0.64 ; and at 194 
 feet, only 0.58. 
 
 A gauge on a plain with a fence 3 feet high around it at a distance 
 of 3 feet will collect 6 per cent, more rain than without the fence. 
 These differences are due entirely to wind currents. 
 
 Forests intercept from 6 to 15 per cent, of the rainfall in different 
 rain storms. 
 
 INSTRUCTIONS FOR USE OF THE RAIN-GAUGE. 
 
 The Weather Bureau solicits the observation and record of rain, 
 snow, and hail, at carefully selected stations, with a three-fold object: 
 to benefit commerce on navigable streams, to assist the operations 
 of agriculture by irrigation and water storage in regions where the 
 rainfall is insufficient at the time when the crops most require water, 
 to enable specialists of the bureau to gain such knowledge of the 
 climate of the several regions of the country as will permit them to 
 supply engineers and others with the facts which are needed to govern 
 them in the construction of waterworks and other undertakings. 
 These eminently practical benefits are to be obtained only by care- 
 fully prepared records of observations of the rainfall made at many 
 stations. To secure accuracy each observer should study the in- 
 structions herewith offered for his guidance. 
 
 Each station will be equipped with a standard rain-guage, and, if 
 possible, a wooden box support, complete, which is to be mounted 
 in the manner described below. 
 
 The rain-gauge consists of three parts 
 The receiver, A. 
 The overflow attachment, B. 
 The measuring tube C. 
 
 The top cylindrical portion of the receiver, marked a in Fig. 12, is 
 exactly 8 inches in diameter inside, and is provided with a funnel- 
 shaped bottom, which conducts any precipitation falling into the 
 receiver into the tall cylindrical measuring tube, C, the total height 
 of which, inside, is exactly 20 inches. The diameter of this tube is 
 much smaller than the large receiving tube, a, being only 2.53 inches. 
 In consequence of this a small amount of rain falling into the re- 
 ceiver and flowing into C fills the latter to a depth greater than the 
 actual rainfall in proportion as the area of the receiver is greater 
 than the area of the measuring tube. In the standard gauges of the 
 Weather Bureau the depth of the rainfall, in accordance with this 
 principle, is magnified just ten times. The receiver, A, has a sleeve, 
 </, Fig. 13, which slips over the tube, C, and very effectually prevents 
 
45 
 
 any loss of rainfall. Again, when the rainfall is very heavy the 
 tube, C, may be more than filled. In this case to still prevent loss a 
 little opening, shown at <?, Fig. 14, is made in the sleeve, d> just on a 
 level with the top of the tube, C. The excess of rainfall escapes 
 through this opening, and is retained in the large overflow attach- 
 ment, B, and can be measured afterwards, as will be described below. 
 In the drawing the diameter of the overflow attachment is shown as 
 less than 8 inches, but in the latest style gauges this part is now also 
 made just 8 inches inside diameter. The object of this is to be able 
 to use this portion of the instrument as a snow gauge, as will be ex- 
 plained hereafter. 
 
 Fig.lZ. 
 Front View. 
 
 Pig. 13. 
 Vertical Section. 
 
 RAIN GAUGE. 
 
 \ 
 
 --. 
 
 f 
 
 4 
 
 B 
 
 ? 
 
 C 
 
 d 
 3 
 
 Receiver. 
 
 Fig.15. 
 Horizontal Section,E-i; 
 
 I 234 56 7 Q 9 10 II 12 13 14 IS- 16 17 IB 19 20 21 
 
 & \*uu. 
 
 SCALE. 
 EXPOSURE OF RAIN-GAUGES. 
 
 It is desired observers use particular care in selecting a good place 
 of observation, as the value of the records is sometimes greatly im- 
 paired by improper exposure. It is scarcely necessary to say that 
 every precaution should be taken to protect gauges from the inter- 
 ference of animals and unauthorized persons. Select, if possible, a 
 position in some open lot as unobstructed as possible by trees, build- 
 ings, or fences. Such a place in general affords the best exposure, 
 though sometimes difficult to find. Gauges should be exposed upon 
 roofs of buildings only when necessary, and then the roof should be 
 flat, or nearly so. The middle portion of a flat unobstructed roof 
 generally gives the best results. 
 
46 
 
 RAIN-GAUGE SUPPORT. 
 
 The box in which the gauge is shipped to the observer is expressly 
 designed as a stand for the instrument, and should be opened at the 
 head, which is fastened by screws. Set the box up as nearly vertical 
 as possible at the place selected for the exposure and ballast by fill- 
 ing the lower portion with several inches of stone or broken brick. 
 Slip in the head and lower to the level of the screw holes in the sides 
 of the box about 10 inches from the bottom, where the head is 
 securely fastened with the screws taken out in opening the box. 
 The support is further secured and fixed in its position by piling 
 up a few stones around the outside. The gauge can now be placed 
 inside and appears as shown in Fig. 16. 
 
 Ratn Gauge cutoi Support. 
 
 FIG. 16. 
 
 TO MEASURE RAINFALL AND SNOWFALL. 
 
 Rainfall. The rain-gauge measuring stick is graduated into inches 
 and tenths of inches. Remembering that the actual depth of the 
 rainfall is magnified ten times, as explained above, it is plain that 
 if we find the water 10 inches deep .in the measuring tube, then the 
 real rainfall must have been only one inch deep, or, if the water in 
 the tube is only one-tenth inch (or written as a decimal .1 inch) deep, 
 then the rainfall must have been only one one-hundreth inch (or 
 written as a decimal .01 inch). 
 
47 
 
 To save observers the trouble of always thinking about the mag- 
 nification, and to avoid possible errors in reports, the numbers on 
 the graduation of the measuring sticks are not actual inches, but in 
 the latest pattern of measuring sticks have all been divided by 10, 
 and thus represent the actual rainfall. Moreover, these numbers 
 are expressed in hundredths of inches of rainfall, and are written 
 as decimal fractions. Thus the ten-inch lige is numbered i.oo (read 
 one and zero hundreths), which is the depth of rainfall in inches 
 corresponding to i-o inches of water in the measuring tube ; similarly 
 the one-inch line is numbered .10 (read ten one-hundredths), which 
 again is the depth of rainfall in inches corresponding to one inch of 
 water in the tube. 
 
 The depth of the water is measured by inserting the measuring 
 stick into the gauge through the small hole in the funnel. When 
 the stick reaches the bottom of the measuring tube it should be held 
 for one or two seconds and then quickly withdrawn and examined 
 to see at what division of the graduation the top of the wetted por- 
 tion comes. The numbering of this division as stamped on the stick 
 gives, as has just been explained, the actual depth of rainfall, and in 
 making out records and reports observers should always use the decimal 
 expressions. Of course it will rarely happen that the top of the 
 wetted portion will fall exactly upon one of the numbered lines it 
 will generally be on or near one of the shortest lines. Thus, for 
 example, suppose the water-mark comes to the sixth short line 
 beyond the line numbered .80, the proper record to make in this case 
 would be .86 inch rainfall. The number of short lines, reckoned from 
 the numbered line next lower, are always to be inserted in place of 
 the o in the stamped numbers. 
 
 Observers should always be careful to put the stick into the gauge 
 so that the end at which the numbering begins goes to the bottom, 
 and the stick passes through the middle of the tube; for if the stick 
 is placed near the sides the water is sometimes drawn up by capil- 
 lary action in the narrow space between the stick and the tube, so as 
 to wet the former entirely too high and give very erroneous records. 
 
 After measuring and recording in this way the water found in 
 the gauge the top should be removed, the measuring tube emptied 
 and drained, and the gauge put in position again. Observers should 
 be careful after emptying the gauge to replace the measuring tube 
 so that the bottom stands within the ring in the middle of the 
 bottom of the overflow, and in putting on the receiver that it passes 
 over the measuring tube and rests squarely down upon the overflow. 
 
 When the amount of rain that has fallen more than fills the meas- 
 uring tube, the total rainfall is determined in the following manner: 
 First carefully remove the receiver so as not to spill any of the 
 water in the measuring tube, which should be exactly full; the latter 
 is then slowly and carefully lifted out so as not to spill any of the 
 
48 
 
 water into the overflow, emptied and allowed to drain a moment or 
 so; the water remaining in the overflow is now poured into the 
 measuring tube, being careful not to lose any, and measured in the 
 usual way. Suppose we find this to be .47 inch rainfall, then, re- 
 membering that the measuring tube is just 20 inches high, the total 
 rainfall will be 2 inches + .47 inch=2.47 inches. 
 
 Snowfall. During the winter season, especially in those climates 
 where the precipitation^ nearly all in the form of snow, it is neces- 
 sary to have only the overflow attachment exposed in the support 
 as a snow-gauge, removing the receiver and measuring tube to the 
 house, as these parts cannot be used for measuring snow, and even 
 if rain should occur it is very apt to be frozen while in the measur- 
 ing tube, generally bursting it and rendering it worthless or highly 
 inaccurate. 
 
 The snowfall collected in the overflow attachment is measured by 
 first placing the vessel in a warm room until the snow is melted. 
 The water is then carefully poured into the measuring tube and 
 measured just as though it were rainfall. 
 
 In addition to this measurement by the gauge a measurement will 
 be made of the actual depth in inches of the snow on the ground. 
 Select a level place of some extent where the drifting is least pro- 
 nounced and measure the snow in at least three places. The mean 
 of these measurements will give the snowfall which is to be entered 
 in the fourth column of the report, and whenever it is impracticable 
 to melt the snow as described in the preceding paragraph, one-tenth 
 of this mean will give an approximate value, in water, for the snow 
 which could not be melted. This value must be set down in the 
 third column of the report in precisely the same manner as rainfall, 
 or snow melted in the gauge. After having once made a measure- 
 ment of the snowfall it is not desired that the same snow be meas- 
 ured at each succeeding observation until it shall finally disappear. 
 Any fresh snow, however, should be measured and recorded as it 
 falls. If there be any snow on the ground at the middle and end of 
 the month that fact and the depth in inches should be noted. 
 
 Observations should be made every evening, also at the close of 
 every storm, and the gauge should be emptied of all the water it may 
 contain as soon as it has been measured. 
 
 The form supplied for these records will be found self-explanatory. 
 Rainfall observers will disregard the columns headed "Tempera- 
 ture," and confine their attention to those headed " Precipitation." 
 The first and second columns have to do with the time of beginning 
 and ending of the storm, and together measure its duration. In 
 the third column is to be entered the reading of the gauge, as de- 
 scribed on pages 46 and 47 of these instructions. If no rain, 
 snow, or hail has fallen during the period of observation make the 
 entry .00, or "No precipitation," in this column. If the amount is 
 
49 
 
 too small to measure make the entry " Trace." The fourth column 
 is provided for the record of snow measurements made by the 
 method described on page 48. In the "Monthly Summary" all 
 matters indicated are proper subjects of the rainfall observer's 
 record, with the exception of the three lines which deal with tem- 
 perature. 
 
 It is particularly important in the interests of accuracy that the 
 observations be recorded as soon as made, and that the daily entries 
 be made day by day. The forms for each month should be mailed 
 on the first day of the succeeding month. Even if no rain has fallen 
 the observer should bear in mind that his official record of that fact 
 is as important as though it were a month of rain. 
 
 Requisition for blank forms or envelopes may be made at any 
 time, and will receive immediate attention. It is not necessary to 
 write a letter asking for them; a simple note on the margin of the 
 monthly report will be sufficient. 
 
 PERCOLATION GAUGE. 
 
 An instrument for measuring the rainfall that reaches different 
 depths in the earth is a percolation gauge, sometimes called a 
 lysimeter. It consists of an iron vessel, imbedded in the earth, 
 three feet in diameter and three feet deep, filled with earth, and the 
 top surface level with the ground. There is a pump for drawing 
 off the water that collects in a depression on one side at the bottom 
 of the vessel, which then has to be measured. 
 
 The amount of rainfall that reaches a depth of three feet is only 
 about one-third or one-fourth of the annual depth of rainfall as 
 measured at the surface of the ground. It varies a good deal with 
 the nature of the soil. 
 
 WIND VANE. 
 
 The wind vane is the instrument by which the direction of the 
 wind is observed. The direction of the wind is always considered 
 as the direction from which it is coming. The direction is noted to 
 the nearest principal point of the compass from which it is blowing, 
 north, northeast, east, southeast, south, southwest, west, or northwest. 
 
 A calm is recorded when there is not sufficient wind to move the 
 anemometer cups. 
 
 The motion of smoke from chimneys can be used to observe the 
 direction of feeble currents of air, too weak to turn the wind vane. 
 
 The Weather Bureau form of wind vane is shown in Fig. 17. The 
 arrow is about 6 feet long ; the tail piece is of pine 10 inches wide, 
 split to form an angle 'of about 10. This is considered to 
 steady the direction of the vane and render it more sensitive to the 
 action of light currents than if it were a plain board. 
 
 The wind vane should be set in as free and open a space as 
 possible, away from every obstacle, especially high buildings. It 
 should be 8 or 10 feet above a roof. 
 
Friction. Roller. 
 
 Wind Vcvne and, Ceittng Died. 
 FIG. 17. 
 
51 
 
 In the complete form of wind vane there is a rod connecting with 
 the vane, passing through the support and the roof of building and 
 attached to an index centered in a dial on the ceiling of a room. 
 The principal points of the compass are marked on dial, and the 
 wind direction can be noted without direct observation of the vane. 
 
 In noting changes in the direction of wind the terms veering and 
 backing are used. Veering is a change in the direction from the 
 north to the northeast, through the east to the southeast, southeast 
 to south and southwest, etc., corresponding to fhe direction of mo- 
 tion of the hands of a watch. Backing is changing in the reverse 
 direction, around by north, through the west, etc. 
 
 ANEMOMETER. 
 
 The instrument generally used in determining the velocity of the 
 wind is the Robinson anemometer, shown in Fig. 18. 
 
 FIG. 18. 
 
 It consists of four hollow hemispherical cups 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. The 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. 
 
 9377 4 
 
52 
 
 The center of the cups moves with a velocity about one-third 
 that of the wind which puts them in motion. 
 
 The cups are 4 inches in diameter. The distance from center of 
 cup to center of rotation or axis is 6.72 inches. On the assumption 
 that the wind travel is exactly three times that of the center of cup, 
 the dials are marked to register miles of wind travel, 500 revolu- 
 tions 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. 
 
 The true velocities corresponding to observed velocities areas fol- 
 lows : 
 
 Observed ve- True velocity, 
 
 locity, miles miles per 
 
 per hour. hour. 
 
 
 
 10 9.8 
 
 20 17. 8 
 
 30 25. 7 
 
 40 33. 3 
 
 50 40. 8 
 
 60 48. 
 
 70 55. 2 
 
 80 62. 2 
 
 90 69. 2 
 
 The pattern of anemometer used in the Weather Bureau has the 
 registering dials mounted concentrically. The outer dial has one 
 hundred and the inner dial ninety-nine divisions. As the dials are 
 moved by the same wheel, they will move forward one hundred 
 divisions in the same time (Fig. 19). The outer dial having one 
 hundred divisions, the inner dial will complete one revolution and 
 its zero be one division beyond or to the left of the zero of the outer 
 dial when the outer dial has completed one revolution, the zeros of 
 the scales coinciding at the time the instrument was set in motion. 
 Thus the revolutions made by the outer dial are recorded on the 
 innei- one, the number of revolutions being shown by the number 
 of divisions of the scale on the inner dial between the zero of that 
 scale and the zero of the outer one. In taking the reading of the 
 anemometer at any time, the hundreds and tens of miles are read 
 from the inner scale and the miles and tenths of miles are read from 
 the outer one. Take from the inner scale the hundreds and tens of 
 miles contained between the zero of that scale and the zero of the 
 outer one, and the miles and tens of miles on the outer scale con- 
 tained between the zero of that scale and the index of the instru- 
 ment, and the sum of these readings will be the reading of the 
 instrument at the time of making the observation. 
 
 When the anemometer is not furnished with an index point the 
 center of the small wheel which gives motion to the dials will be 
 taken as the reference point. 
 
53 
 
 The total movement for the twenty-four hours wil be obtained 
 in the following manner : Subtract the reading of the anemometer 
 at 12 noon of the preceding day from the reading taken at 12 noon 
 of the current day, and the difference will be the total movement of 
 the wind. When the reading of the anemometer is less than the 
 reading of the preceding day, 990 miles will be added to it, and the 
 remainder, after sulitracting the reading of the preceding day, will 
 be the total movement. 
 
 Example : The* dial reading of to-day is 91, and that of yesterday 
 was 950, hence we have 91 + 990 = 1081 ; 1081 950=131, the total 
 observed movement of the wind in miles during the past twenty- 
 four hours. 
 
 Anemometers must be kept carefully and thoroughly oiled to 
 prevent friction and injury to the several bearings. Especial 
 attention must be given to the large dial-screw, and when found 
 loosened it must at once be tightened, but care must be taken not 
 to screw it up tight enough to interfere with the free motion of the 
 dials. 
 
 The pressure of the wind on a surface varies as the square of the 
 velocity. The pressure in pounds per square foot of vertical expos- 
 ure of a surface is equal to 0.004 multiplied by the square of the true 
 wind velocity in miles per hour. 
 
 When there is no anemometer for measuring the velocity, the 
 force of wind is estimated according to a scale of numbers from i to 
 12. The scale in most common use, especially at sea, is the Beaufort 
 scale. Estimates on this scale at sea are made for the most part 
 according to the commotion the wind causes in the water or the 
 rigging of a ship. This arbitrary scale originated in the days of 
 sailing vessels. The wind force was indicated by the various num- 
 bers according to the amount of sail that could be safely carried. 
 The velocity in miles per hour corresponding to the different num- 
 bers has been ascertained by comparison of the estimated force on 
 ships at sea with actual velocities observed by anemometers on 
 shore in the vicinity at the same time. 
 
 The scale is as follows: 
 
 Wind force, 
 Beaufort scale. 
 
 
 Velocity, 
 miles per hour. 
 
 
 
 Calm 
 
 
 
 1 
 
 Light air 
 
 3 
 
 2 
 
 Light breeze _ 
 
 13 
 
 3 
 
 Gentle breeze 
 
 18 
 
 4 _ 
 
 Moderate breeze _ _ 
 
 23 
 
 5 
 
 Fresh breeze 
 
 28 
 
 6 
 
 
 34 
 
 7 
 
 Moderate gale 
 
 40 
 
 8 
 
 
 48 
 
 9 _ 
 
 Strong gale 
 
 56 
 
 10 
 
 Whole gale 
 
 65 
 
 11 
 
 Storm 
 
 75 
 
 12 
 
 Hurricane _ _ 
 
 90 
 
 
 
 
64 
 
 The above velocities are not corrected for the errors of anemom- 
 eter. The velocities are those observed with the English pattern 
 of anemometer at coast stations in Great Britain. This anemometer 
 has larger cups and longer arms than the Weather Bureau pattern of 
 instrument. It is geared and dialed on the supposition that the 
 
 FIG. 19. ANEMOMETER DIAL. 
 
 wind travel is exactly three times the travel of center of cups. At 
 30 miles an hour it is probably 2.4 times the velocity of cup instead 
 of 3.0, as shown by Dohrandt's experiments with specimens of the 
 instrument at St. Petersburgh, which makes an indicated velocity 
 of 30 miles correspond to a true velocity of 24. 
 
55 
 
 CLOUDS. 
 
 There is a very great variety of cloud forms. Seven typical forms 
 are recognized for meteorological observation according to Howard's 
 classification. 
 
 Cirrus. 
 
 Cumulus. 
 
 Stratus. 
 
 Cirro-cumulus. 
 
 Cirro-stratus. 
 
 Cumulo-stratus. 
 
 Nimbus. 
 
 Cirrus. Cirrus cloud, the highest of all clouds, is a streaky, gauzy, 
 wispy or feathery form of cloud, whitish in color, usually not very 
 abundant. It forms at great heights, 25,000 to 50,000 feet, rarely 
 occurring below 16,000 feet. It is sometimes known as "cat's whisk- 
 ers" and "mares' tails." 
 
 Cumulus. Cumulus cloud is masses of compact cloud of a dense 
 rounded appearance, like cotton bulging from a bale. It has a flat, 
 horizontal base 3,000 to 5,000 feet above the ground, and towers up 
 conically to a great height in the sky. Its shape indicates it is the 
 result of the condensation of moisture as the air in ascending cools 
 dynamically to the dew point. Cumulus cloud forms the visible 
 capital of an ascending column of air. It is essentially a day cloud. 
 It is more common in the afternoon than the morning, and is most 
 noticeable when the sun is low. It is frequent at all times of the 
 year. 
 
 The distant tall tops of cumulus visible on the horizon at sea are 
 known as "thunderheads." 
 
 Stratus. Stratus cloud is a widely extended sheet of uniform 
 cloud, named from its resemblance to the regular arrangement of a 
 stratum of rock or clay. It is a fog lifted up floating in the air. It 
 is the lowest of all forms of clouds, the height not being more than 
 1,000 to 2,000 feet. It is essentially a cloud of the night, forming by 
 radiation of heat from the lower layers of the air. 
 
 Cirro-cumulus. Cirro-cumulus is a broken layer of cloud made of 
 little bunches of whitish cloud, elliptical or elongated patches with 
 somewhat regular interstices between them without any shading of 
 light. It is mostly visible near sunset, but always high up in the 
 sky, at a height of 12,000 to 22,000 feet. It is denser than the cirrus 
 and of a dark "tone." This is the form of cloud to which the line of 
 poetry applies: 
 
 " The beauteous semblance of a flock at rest." 
 
 Cirro-stratus. Cirro-stratus is a thin veil of widely extended cir- 
 rus. It is a high cloud. At times it is largely composed of ice 
 particles, as shown by the colored rings seen around the sun and 
 
56 
 
 moon viewed through it. Lunar halos are frequent with this form 
 of cloud. 
 
 Cirro-stratus is also at times a condensed and developed form of 
 cirrus in which the streakiness is very marked, on account of the 
 great extent of cirrus. At times ribs of cirro-stratus stretch from 
 a point on the horizon to a point directly opposite. This is an effect 
 of perspective, the streaks appearing wider apart at the zenith. 
 This form of cloud is sometimes known as "polar bands." The 
 stripes or ribs are sometimes made up of cross-bar patches and then 
 are said to be "striated." The fibres of cirro-stratus sometimes 
 interlace and have a reticulated appearance like woven cloth. 
 
 Cumulo-stratus. Cumulo-stratus is composed of great masses of 
 dense dark cloud, usually covering the whole sky. It prevails at a 
 height of 5,000 to 10,000 feet. It is essentially a cloud of the night 
 and the cold season. The darker forms of cumulo-stratus sometimes 
 present an unduiatory aspect, especially toward the horizon, an effect 
 of perspective. This is sometimes called "roll-cumulus." In high 
 latitudes in winter thick masses of this cloud obscure the sky at 
 times for weeks. 
 
 Nimbus. Nimbus is a dense thick layer of dark cloud, void of shape 
 or form, without definite edge, and of tattered, ragged outline, from 
 which rain or snow is continuously falling. 
 
 Scud is the small detached scurrying masses of cloud in advance 
 of and lower down than the main nimbus cloud. 
 
 Cloud observations consist in estimating the part of the sky cov- 
 ered at any time by clouds, the form of the clouds, and their direction 
 and rate of motion. The form of cloud prevailing indicates some- 
 thing as to the condition of the upper air; their movement indicates 
 the direction and rate of motion of the upper currents. 
 
 The proportion of sky covered by clouds is determined by inspec- 
 tion in tenths of the whole visible firmament. A sky wholly over- 
 cast is recorded as 10; a perfectly clear sky is indicated by o. Only 
 an approximation to the true amount of sky covered can be made 
 by estimation. To assist in this estimation it maybe useful to note 
 that the sky will be divided into 10 equal parts, as regards angular 
 magnitude as seen by an observer, by lines from five equi-distant 
 points on the horizon to the zenith and by a horizontal circle at one- 
 third of the distance from the horizon to the zenith. 
 
 Sometimes estimates of cloudiness are made on a scale of o to 4, or 
 quarters of the sky covered. 
 
 The form of cloud is noted which is considered to be the nearest 
 to one of the forgoing types described. The purely typical forms 
 are of relatively rare occurrence. 
 
 Observation of the direction of motion of the clouds is beset with 
 great difficulty in most cases, from the fact that the form of cloud 
 is continually changing, and often from the uniformity of texture it 
 
57 
 
 is impossible to identify a point on a cloud for comparison with some 
 motionless object on the surface of the earth. In the case of clouds 
 some distance from the zenith, the direction of motion observed must 
 be made free of the effects of perspective. 
 
 CLOUD MOVEMENT. ' 
 
 The great difficulty in getting at the true direction of cloud move- 
 ment lies in the effect of perspective. The following device obviates 
 'this: 
 
 " Set up a pointed pole, reaching 6 or 8 feet above the observer's 
 head, and through the top, an inch or so below the point, fix two 
 stout cross-wires, or thin iron rods, set truly by compass to the four 
 cardinal points. The space around the pole must be sufficiently 
 open to allow of a good view of the sky in all directions. Let the 
 observer then station himself at such a distance from the pole, and 
 in such a position that some recognizable portion of a cloud appears to 
 move vertically upward from the top of the pole or vertically down- 
 ward toward it. The direction of the pole from the observer's 
 position (which may be judged of accurately by means of the cross- 
 wires on the top) is the direction of the cloud's true movement. 
 With a little care in selecting the position the pole may be dispensed 
 with, as any pointed object will serve the purpose, provided the 
 observer has previously acquainted himself accurately with the 
 points of the compass. The velocity of cloud movement may be 
 measured in favorable situations by observing the time that the 
 shadow takes to traverse a certain space of country, the extent of 
 which is accurately known/' 
 
 The direction from which the clouds are moving should be recorded 
 to 8 points N., NE,, E., etc. The velocity may be recorded by the 
 letters s (slowly) and r (rapidly) placed as an exponent to the direc- 
 tion thus, N r , S 8 . 
 
 Haze, smoke, and fog should be recorded as such, with the addition 
 of the words " light " or " dense," as the case may be. 
 
 EVAPORATION. 
 
 Depth of evaporation in inches from a water surface is measured 
 by means of an evaporometer or atmometer. A common form con- 
 sists of a round dish i foot in diameter and 4 inches deep. The 
 depth of evaporation is ascertained from the loss of weight by means 
 of weighing at different times. Sometimes this is observed by means 
 of a graduated scale inside the dish, so arranged that the height of 
 water surface can be read at any time. Sometimes the scale is 
 inclined so as to give a magnified reading of the fall of surface. 
 
 The vessel is kept in the open air and free from the direct rays of 
 the sun. Readings of the scale are made daily. The differences of 
 readings give the depth of evaporation in the intervening time. 
 
58 
 
 The dish has to be protected from wind and rain, which interfere 
 with exact observation. 
 
 The Piche evaporometer, shown in Fig. 20, consists of a glass tube 
 about 9 inches long and 0.4 of an inch internal diameter, closed at 
 the top and open below, graduated to show equal volumes 
 contained. It is filled with water and the end covered 
 with a paper disk 1.2 inches in diameter, held in place by 
 a metal plate attached to a spring on a slitted brass 
 collar moving easily along the tube. The water flows 
 down to the paper, from which it evaporates both on 
 the upper and under sides. The amount of evaporation 
 in a given time is obtained by taking the difference in 
 the readings of the top of the column of water in the 
 tube. 
 
 A paper surface gives off about one-third more water 
 in a given time than an equal extent of water surface 
 in a dish. 
 
 With a wind velocity of 5 miles an hour the evaporation 
 is 2.2 times as great as in a calm ; with 10 miles, 3.8; 
 with 15 miles, 4.9; with 20 miles, 5.7; with 25 miles, 6.1; 
 with 30 miles, 6.3. 
 
 RIVER GAUGE. 
 
 A river gauge is a device for measuring the vertical 
 height of a river surface above some arbitrarily selected 
 plane, usually at or somewhere near the level of the 
 lowest water that occurs at the place. 
 
 When possible, without too great expense, a river FIG. 20. 
 gauge is made vertical. It consists of a plank or planks 2 inches 
 thick and 8 to 12 inches wide, fastened to a bridge pier or piling, 
 and of sufficient length to cover the greatest range in height of 
 water ever likely to occur. 
 
 The plank is graduated to feet and half feet usually, and the 
 height of surface of water on it can be read by estimation to the 
 nearest tenth of a foot. 
 
 With the zero of the gauge graduation at or near low water, the 
 reading of the water surface on the gauge at any time is called the 
 stage of the river. 
 
 When a gauge has to be read on a bridge pier by an observer on 
 shore at a distance of 50 or TOO feet, in order to render the various 
 foot and half-foot marks the more conspicuous and legible and 
 readily recognizable, the gauge is painted in alternate patches or 
 triangles of black and white, according to some such design as that 
 shown in Fig. 21. 
 
 To prevent obscuring of the foot and half-foot marks by weather- 
 ing, they are indicated on the plank by rows of copper tacks driven 
 into the plank. 
 
59 
 
 Only the whole foot marks are numbered, and this is likewise 
 done in copper tacks. 
 
 Sometimes a river gauge consists of a strip of the surface of a 
 stone pier dressed down to a smooth surface so as to receive the 
 marking and numbering of gauge. 
 
 When a river gauge cannot be set vertically on a bridge pier, it 
 is laid along the bank according to the slope of the ground. It 
 should then be made of logs or heavy timbers 6 
 inches by i foot imbedded in the ground, with the 
 top surface even with the surface of the ground in 
 the river bank. Strap iron X f an i ncn thick and 
 2 inches wide is spiked along the top surface, and 
 [on it are cut the foot marks and intermediate half 
 foot or tenths of foot marks and the numbering of 
 the feet showing various heights above the zero of 
 the gauge. The foot marks on a gauge of this kind 
 must be accurately located by a civil engineer by 
 means of a spirit level. 
 
 Sometimes a very substantial inclined gauge is 
 made of lengths of block stone with bars of railroad 
 iron inlaid, on which the foot marks are cut. 
 
 Sometimes a gauge is made of isolated stone piers 
 buried in the'ground along the bank, the top surface 
 showing the height in feet above an assumed low- 
 water plane. 
 
 It is not always possible at the time of setting a 
 gauge to put the zero of the graduation at the exact 
 level of the lowest water apt to occur. 
 
 When a stage of water below the zero occurs, it 
 is read as a minus stage. It is desirable that the 
 zero shall be put so low that this will never occur, as 
 the minus sign is apt to lead to confusion, the same 
 FIG. 21. numerical stages indicating very different levels of 
 water, whether plus or minus. 
 
 A gauge once established and a long record of readings made, it 
 is not advisable to ever change the zero of the gauge. It is not 
 customary to change it, even if there does occur a stage of water 
 lower than any before known. 
 
 For the purpose of ascertaining from time to time any changes 
 that may occur in the level of the zero of a gauge or any of its 
 marks, a bench mark is established close by the gauge or somewhere 
 in its vicinity. 
 
 A bench mark consists of some accessible, presumably permanent 
 point or surface, the difference in level between which and the zero 
 or some other mark on the gauge is known by actual leveling be- 
 
60 
 
 tween the two by means of a spirit level. When this difference is 
 found to vary it is presumed it indicates a corresponding- change in 
 the level of the marks of the gauge, requiring adjustment of the 
 gauge or correction of its readings. 
 
 A bench mark is essential in case a river gauge is to be repaired 
 or renewed, in order to set the new gauge at exactly the same level 
 as it was before. 
 
 On a bridge pier the top surface of the largest stone accessible 
 in the top course of masonry is often used as a bench mark. Some- 
 times a bench mark is the top surface of a large stone buried in the 
 ground especially for the purpose of establishing a permanent 
 surface. Prominent surfaces in stone buildings are good places for 
 permanent bench marks. A copper bolt set in the stone wall of 
 some public building, such as a custom house, post office, or city 
 hall, is a common -device for a bench mark in a large city. 
 
 STATE OF THE WEATHER. 
 
 The weather is recorded clear when the sky is -^ - or less obscured; 
 fair, when the sky is from -fo to ^- obscured; cloudy, when the sky 
 is more than -$ obscured; light rain (//. r.), when there is light rain; 
 heavy rain (hy. r.\ when there is heavy rain; in like manner with 
 light and heavy snow, substituting s for r; fog, haze, smoke, accord- 
 ing as these are predominant. 
 
 FROST. 
 
 Occurrence of first and last frost of any growing season should 
 be specially noted, as well as all killing frosts during the same. 
 
 CORONA. 
 
 These must be distinguished from halos. Coronae are very common, 
 especially around the moon, and are produced by the rays passing 
 through a thin layer of cloud. Sometimes as many as three small 
 concentric circles may be seen whose diameters are in the ratio of 
 1:2:3. They are frequently colored, red being the outside color. 
 These colors are not the pure colors of the spectrum, but rather those 
 of the opal, and are caused by interference and not refraction. A solar 
 corona is not often visible on account of the dazzling brightness of 
 the sun, but it may often be seen by viewing the sun through colored 
 glass, or noticing its reflection in water. 
 
 Halos are large circles of 45 or 90 in diameter. That is, the 
 diameter is equal to one-eighth or one-fourth the circumference of 
 the horizon. Both are seldom seen at the same time. The colors 
 are very feeble, generally approaching whiteness. Halos arise from 
 the presence in the atmosphere of minute prisms of ice, and are due 
 to refraction of light. Sometimes the halo is intensified into two 
 bright spots, one on each side of the central luminary. These are 
 
61 
 
 called "parhelia" or " paraselenae " (mock S4ins or mock moons), 
 sometimes sun-dogs. Still more complicated optical phenomena are 
 sometimes seen, though rarely, except in high latitudes. 
 
 THUNDER STORMS. 
 
 Thunder storms six hours apart may be considered as separate 
 storms. 
 
 Upon the occurrence of thunder, give as nearly as possible the 
 times of first and loudest thunder and duration of thunder (being 
 careful to note a. m. or p. m. if the hours o to 24. are not used). 
 
 Give the direction from which the storm appears to be coming, as 
 shown by threatening sky, lightning flashes, or thunder peals. Also, 
 the direction toward which it goes. 
 
 TORNADOES AND SAND SPOUTS. 
 
 All the meteorological circumstances attending these should be 
 minutely noted, viz: the course of the barometer, which almost 
 always sinks much and rapidly; that of the thermometer, which 
 usually indicates an elevation of temperature; the region of the 
 heavens in which the thunder storm frequently accompanying them 
 is formed; the form and color of the clouds; the direction and in- 
 tensity of the wind; the frequency, intensity, and form of the light- 
 ning; finally, the apparent shape of the sand-spout, its variations, its 
 course, and its effects upon the trees and upon the ground, the oc- 
 currence of hail, etc. 
 
 INSTRUCTIONS FOR OBSERVING AURORAS. 
 
 Though the aurora borealis has received attention during a con- 
 siderable portion of the last two centuries, definite information is 
 still wanting on several points which may serve as the basis of a 
 sound induction as to its. cause. These relate particularly to the 
 actual frequency of its appearance; its comparative frequency in 
 the different months of the year and the different hours of the day; 
 the connection of its appearance with other atmospherical phenom- 
 ena; the elevation and extent of visibility of the arch; and whether 
 the same or different phases are presented to individuals at different 
 stations at the same moment of time; finally the precise influence of 
 the arches, streamers, etc., on the magnetic condition of the earth; 
 and whether any unusual electrical effects can be observed during 
 the appearance of the meteor. 
 
 Auroral phenomena may be divided into the following classes: 
 
 1. A faint light in the north, without definite form or boundary. 
 
 2. A diffused light, defined by an arch below. 
 
 3. Floating patches of luminous haze sometimes striated. 
 
 4. One or more arches, of rainbow form, of uniform white color, 
 
62 
 
 retaining the same apparent position for a considerable time, and 
 varying in luminosity. 
 
 5. A dark segment appearing tinder the arch. 
 
 6. Beams, rays, streamers, waves, transverse and serpentine bands, 
 interrupted or checkered arches, frequently tinged with color, and 
 showing rapid changes in form, place, and color. 
 
 7. Auroral corona, or a union of beams south of the zenith. 
 
 8. Dark clouds accompanying the diffuse light. 
 
 9. Sudden appearance of haze over the whole face of the sky. 
 The following may serve as a scale of brightness: (i) Faint; (2) 
 
 Moderate; (3) Bright; (4) Very bright. 
 
 GENERAL DIRECTIONS. 
 
 1. Make a regular practice of looking for auroras every clear 
 evening, from 8 to 10 o'clock or later. Record the result, whether 
 there be an aurora or not. 
 
 2. Note the time of observation, and compare the watch used with 
 a correct clock, as soon after as is convenient. 
 
 3. Make a record of the latitude and longitude of the station. 
 
 4. Note the class to which the auroral phenomenon belongs. 
 
 5. If it be an arch, note the time when the convex side reaches 
 any remarkable stars, when it passes the zenith, disappears, etc. 
 
 6. If the arch be stationary for a time, note its position among 
 the stars, so that its altitude may be determined. 
 
 7. If it be a streamer or beam, note its position, and the time of 
 its beginning and ending. 
 
 8. If motion be observed in the beams, note the direction, whether 
 vertically or horizontally, to the east or west. 
 
 9. Note the time of the formation of a corona, and its position 
 among the stars. 
 
 10. Note the time of the appearance of any black clouds in the 
 north near the aurora; also, if the sky be suddenly overcast with a 
 mist at any time during the auroral display. 
 
 11. Give the direction and force of the wind at the time. 
 
 12. Note if any electrical effects are observed. 
 
 13. Note the effect upon a delicately-suspended magnetic needle. 
 
 14. The date, hour, and minute of the beginning and ending of 
 auroras should be carefully noted, as well as the azimuth and alti- 
 tude of each extremity and of the crown of any arch of light, and 
 the same data for any corona or glory that may be formed. 
 
 When the observer is familiar with the names of the principal 
 fixed stars, he may locate the arch or crown by reference to them, 
 but it is preferable that he should observe directly the altitude and 
 azimuth. 
 
 Altitudes are expressed by degrees from the horizon to the zenith. 
 
63 
 
 If any circle be divided into three hundred and sixty parts, and 
 the radial lines connect these parts with the center, each pair of 
 lines subtends an angle of i; the fourth 'part of the circle will 
 subtend an angle of 90 or one right angle, and the corresponding 
 radii are perpendicular to each other; thus the zenith (that point 
 of the heavens immediately above the observer) is 90 from the 
 horizon, or, in other words, its altitude is 90. A point halfway up 
 from the horizon to the zenith has an altitude of 45. 
 
 Azimuths are also expressed in degrees, but are measured on the 
 horizontal plane, and will be recorded, as is done in astronomy, from 
 the south point to the westward, passing, successively, the west, 
 north, and east points of the compass until 360 have been passed 
 over, and the south point is again reached. 
 
 Observers should be particular as to the date of the aurora; and 
 when it begins in the evening of one day and continues into the 
 early morning of the next day, it will be entered as occurring on 
 the first day, but its details will be given in the record as occurring 
 between the hours of its actual beginning and ending. Thus, an 
 aurora that began on the evening of the i2th of January and con- 
 tinued until the early morning of the i3th would be entered as the 
 aurora of the i2th, but its details would be recorded as occurring, 
 for instance, between the hours of 10 p. m. of January 12 and 2 a. m. 
 of January 13. 
 
 Professor Olmstead, in a paper published by the Smithsonian 
 Institution, classifies different auroras as follows: 
 
 " Class I. This is characterized by the presence of at least three 
 out of four of the most magnificent varieties of form, namely, 
 arches, streamers, corona, and waves. The distinct formation of the 
 corona is the most important characteristic of this class; yet, were 
 the corona distinctly formed, without auroral arches or waves, or 
 crimson vapor, it could not be considered as an aurora of the first 
 class. 
 
 " Class II. The combination of two or more of the leading charac- 
 teristics of the first class, but wanting in others, would serve to 
 mark class the second. Thus the exhibition of arches and streamers, 
 both of superior brilliancy, with a corona, while the waves and 
 crimson columns were wanting, or of streamers with a corona, or of 
 arches without a corona, without streamers or columns (if such a 
 case ever occurs), we should designate as an aurora of the second 
 class. 
 
 " Class III. The presence of only one of the more rare character- 
 istics, either streamers or an arch, or irregular coruscations, but 
 without the formation of a corona, and with but a moderate degree 
 of intensity, would denote an aurora of the third class. 
 
 " Class IV. In this class we place the most ordinary forms of the 
 aurora, as a mere northern twilight, or a few streamers, with none 
 
64 
 
 of the characteristics that mark the grander exhibitions of the 
 phenomenon." 
 
 The same author remarks: 
 
 "On the evening of the 2yth of August, 1827, after a long absence 
 of any striking exhibition of the aurora borealis, there commenced 
 a series of these meteors, which increased in frequency and mag- 
 nificence for the ten following years, arrived at a maximum during 
 the years 1835, 1836, and 1837, and, after that period, regularly 
 declined in number and intensity until November, 1848, when the 
 series appeared to come to a close. The recurrence, however, of 
 three very remarkable exhibitions in September, 1851, and of another 
 of the first class as late as February 19, 1852, indicates that the close 
 was not so abrupt as was at first supposed; but still there was a very 
 marked decline in the number of great auroras after 1848, and there 
 has been scarcely one of the higher class since 1853. 
 
 EARTHQUAKES. 
 
 Immediately upon the occurrence of a shock it is desired that the 
 observer will collect such information as will enable him to answer 
 the questions here propounded, and transmit his answers with the 
 least practical delay to the Weather Bureau office. 
 
 If any other reliable information be in his possession, it is desired 
 that he will communicate it at the same time. It is extremely 
 desirable that the nearest possible approximation should be made 
 to the exact time of occurrence, and this should be the first care of 
 the observer who may feel the shock. If the only time-piece is an 
 ordinarily good watch or house clock, it would be advisable to com- 
 pare it with standard time at the earliest practicable moment, which 
 can now be done at most railway stations. 
 
List of questions to be answered by observers of an earthquake shock. 
 
 Station 
 
 Date _ 
 
 1. Was ail earthquake shock felt at your place on the _ day of 
 
 , 18 ? 
 
 (A negative answer is as important as an affirmative one. ) 
 
 2. At what hour, minuie, and second of standard time was it felt f 
 
 3. How long did its perceptible motion continue ? 
 
 4. Was it accompanied by any unusual noise ! If so, describe it 
 
 5. Was more than one shock felt j if so- how many ?. 
 
 6. Which of the following measures of intensity would best describe what hap- 
 pened in your vicinity : 
 
 No. 1. Very light ; noticed by a few persons ; not generally felt. 
 
 No. 2. Light ; felt by the majority of persons ; rattling windows and crockery. 
 
 No. 3 Moderate ; sufficient to set suspended objects, chandeliers, etc. , swinging, 
 or to overthrow light objects. 
 
 No. 4. Strong ; sufficient to crack the plaster in houses, or to throw down some 
 bricks from chimneys. 
 
 No. 5. Severe j overthrowing chimneys and injuring the walls of houses. 
 
 7. Do you know of any other cause for what happened than earthquake ? 
 
 Signature 
 
 65 
 
GENERAL PHENOMENA OF CLIMATE. 
 
 Information of a general character relating to the growth of 
 plants will be of value in compiling the climatology of a district. 
 
 It is suggested that where voluntary observers can do so the fol- 
 lowing be included in their records : 
 
 Time of plowing in the spring. 
 
 Time of planting various crops. 
 
 Time of appearance of same above ground. 
 
 Time of flowering of strawberries, currants, raspberries, apples, 
 plums, and other fruit. 
 
 Time of commencement of haying. 
 
 Time of commencement of harvesting the various cereals. 
 
 Time of ripening of various fruits. 
 
 Time of first killing frost in fall. 
 
 Time of last killing frost in spring. 
 
 Time of sowing fall wheat. 
 
 Time of appearance of earliest shoots of same above ground. 
 
 Time of last snow on ground. 
 
 The depth of snow on ground on the last day of each winter 
 month. 
 
 The time of migration of wild fowl and birds, the nights north 
 and south. 
 
 The time of leafing and fall of leaves in deciduous forests. 
 
 The date of breaking up of ice in large rivers and bays. 
 
 The date of greatest rise and lowest water in important streams. 
 
 Voluntary observers are requested to include in their monthly 
 reports all reliable information relative to the destruction of life 
 and property coming to their knowledge, due to storms, classifying 
 it, as far as possible, as indicated in the following table : 
 
 
 I 
 
 I 
 
 | 
 
 it 
 
 P, 
 
 ill 
 
 S'fl 
 
 -3 
 
 i 
 
 
 0^ 
 
 1 
 
 3 
 
 o 
 
 t OT3~'o 
 
 g'-o'o 
 
 
 * 
 
 
 i 
 
 r 
 
 i 
 
 8 
 
 1 I! 
 
 slil 
 
 
 if 
 
 
 
 
 
 3 
 
 3 o 
 
 s s S o 
 
 
 
 Date of storms. 
 
 Nature of ston 
 northeast gal 
 
 Section of coun 
 by storm. 
 
 Number and u 
 sons killed. 
 
 Number and n 
 sons injured. 
 
 Number and n 
 sels lost or da 
 estimated am 
 
 Number of ho 
 and other b 
 stl'oyed or da 
 estimated am 
 
 Estimated amo 
 age to propei 
 
 Number of ani 
 and estiniatec 
 
 
 
 
 
 
 
 
 
 
 
 66 
 
SPECIAL DIRECTIONS TO THE VOLUNTARY OBSERVERS OF THE 
 WEATHER BUREAU. 
 
 In the reduction of the meteorological records presented to this 
 office, much additional labor 'has resulted from the occasional omis- 
 sion in the records of some impoitant facts, and in want of perfect 
 uniformity in noting the phenomena. To insure uniformity in the 
 records, attention is called to the following remarks. 
 
 1 . Failure to record latitude and longitude, name and station of the observer , 
 and date on each sheet, the observer probably supposing it sufficient to 
 insert them once on the first sheet sent, and so omitting them after- 
 wards. This often renders it necessary to search back through all 
 the series of registers to some one that contained them perhaps in 
 a former year. They should be inserted on every sheet. 
 
 2. Designating the same place by different names, thus rendering it 
 impossible to distinguish whether it is one place or two, unless 
 by noticing the similarity in the name of the observer or in the 
 latitude and longitude. Such changes of name should be avoided 
 when practicable, and when necessarily made, special attention 
 should be called to it. 
 
 3. Diversity in the mode of recording the barometer, as follows : 
 
 (a) Integers record in full, thus, 29.35. (THIS is the proper mode.) 
 () Integers omittted when the same as in the entry next above, 
 thus, 38. 
 
 (c) Integers omitted when the same as in the entry next to the left. 
 
 (d) Integers omitted when the same as in the entry next preced- 
 
 ing in the order of time. 
 
 (e) Integers omitted, except where they are different from the 
 
 usual ones at the place of observation. 
 (/) Integers inserted occasionally and apparently without any 
 
 system whatever. 
 (g) A constant suppressed, and the excess or deficiency recorded, 
 
 as + or . 
 The proper mode is that indicated by (a). 
 
 4. Diversity in the mode of recording the thermometer, when it is below 
 zero, as follows : 
 
 (a) Indicated by the sign placed before it, thus, 16. 
 
 (This is the proper mode). 
 
 (b) Indicated by the same sign placed after it, thus, 16 
 
 (c) Indicated by writing it under a zero, thus, - . 
 
 (d) Indicated by writing it after a zero, with a comma between, 
 
 thus, 0,1 6, 
 
 (e) Indicated by the word "below," or the abbreviation b written 
 
 before or after it, thus, 16 below, i6b, b 16, or below 16. 
 The first (a) is the proper mode. 
 9377 5 67 
 
68 
 
 
 
 5. Departure from the printed instructions in recording the degree of cloudi- 
 ness, some observers reversing the figures and using 10 to denote a 
 clear sky, and o, one entirely overcast; and others omitting the 
 record altogether in the columns of cloudiness when the sky is clear, 
 and in place of it sometimes inserting the word " clear " in the columns 
 of "remarks," or elsewhere. Both lead to error, and -should be 
 avoided; the zero should always be inserted "in the narrow column," 
 as directed, when the sky is clear. 
 
 6. Diversity in the use of the character (0) in recording the motion of the 
 clouds, as follows: 
 
 (a) Used to signify a calm, or that there is no perceptible motion. 
 
 (This is the correct use]. 
 
 (b) Used to signify that the sky is clear, instead of inserting it in 
 
 the proper column. 
 
 (c) Used to signify that no observation was taken. 
 
 (d) Used to signify that the direction in which the upper current 
 
 was moving could not be determined on account of the sky 
 being either perfectly clear or entirely overcast. 
 The first (a) is the correct use. 
 
 7. Want of full and proper records of the direction of the wind, some 
 observers recording the direction only after each change, and then 
 omitting it so long as it continues the same, merely inserting a figure 
 to denote the force. It is better to make the record in full. Other 
 observers record the direction toward which the wind or clouds are 
 moving instead of indicating that from which they come. A WIND 
 from the north, or CLOUDS moving from the north, are to be denoted 
 by N, and from the south by S, etc. 
 
 8. Different kinds of thermometers or different exposures used for the dry 
 and wet bulb thermometers, so that the observations are not comparable 
 
 readily, if at all. 
 
 9. Diversity in the use of the dash and the sign ("), as follows: 
 
 (a) To signify that the entry next above is to be repeated. 
 
 (b) To signify that the entry next to the left is to be repeated. 
 
 (c) To signify that the entry next preceding in the order of time 
 is to be repeated. 
 
 (d) To signify nothing at all, but merely to fill a blank. 
 
 The use of these characters has caused much trouble in the re- 
 duction, and the true remedy would be to avoid them altogether, by 
 making each record complete in itself. 
 
 10. Illegibility of the records, either from defective chirography or 
 from being entered in pencil marks and partly erased. 
 
INSTRUCTIONS IN THE USE OF THE TABLES. 
 
 TABLE I. DEW POINT. 
 
 In Table I are given the temperatures of the dew point as depend- 
 ent on the reading of the dry and wet bulb thermometers. The 
 values apply to roof shelters and whirled wet and dry bulb ther- 
 mometers, but may be used without much error for all shelters well 
 ventilated. The formula from which the table is derived (Ferrel's) 
 for dew points below 32 is: 
 p=p 7 0.000360 P (t t') (14-0-00065 t'), and for dew points above 32: 
 
 t t/ 
 pp' 0.000367 P (t t')(i + ), in which, 
 
 p= vapor pressure of saturation at the dew point temperature. 
 p'= vapor pressure of saturation at the wet bulb temperature. 
 P=barometric pressure taken as 29.4 inches in computing the tables, 
 t =dry thermometer. 
 t'=wet thermometer. 
 
 Example. 
 
 To find the dew point for the reading of the dry bulb 6o.o and 
 the wet bulb 48.o, entering the table on page 75 with t=6o and 
 t t' = i2, we find the dew-point 35. 
 
 There is a small correction to be applied to the value, if great 
 accuracy is desired, when the barometric pressure differs from 29.4 
 inches. This is obtained by the use of Table III, in connection with 
 Table IV. Having found the dew point, the vapor pressure corre- 
 sponding to it is taken from Table IV; in the example above for 35 
 it is 0.203. By means of Table III, with the air pressure, say 27.0 
 inches, and for the difference of dry and wet bulb 12, the 
 correction to the vapor pressure is found to be +0.010. The vapor 
 pressure corrected is then 0.213, an< ^ by Table IV the corresponding 
 dew point is 36. 
 
 TABLE II. RELATIVE HUMIDITY. 
 
 In Table II are given the relative humidities corresponding to the 
 reading of dry and wet bulb thermometers. The relative humidity 
 of the air at any time is the percentage of moisture contained in the 
 air as compared with the whole amount it is capable of holding for 
 the particular temperature at the time. Air containing no moisture 
 is at zero relative humidity; when saturated the relative humidity 
 is 100. 
 
 Example. 
 
 To find the relative humidity for the reading of the dry bulb 6o.o 
 and the wet-bulb 48.o, entering the table on page 85 with t=6o and 
 t t'=i2, we find the relative humidity 39 per cent. 
 
70 
 
 If it is desired to correct the value for the pressure of 27.0 inches, 
 the procedure is as follows: 
 
 In correcting the dew-point for pressure the corrected value in 
 example given above was 36. On page 75 in the column for t t' = i2, 
 the corrected value of 36 is one line lower than the original uncor. 
 rected value 35. Taking the corresponding value of the relative 
 humidity in Table II on page 85, one line lower than 39 in the column 
 for t t'=i2, we have the corrected relative humidity 40 instead of 39. 
 
 Tables III and IV are auxiliary to Tables I and II. 
 
 TABLE IV. 
 
 Table IV gives the vapor pressure at saturation for various tem- 
 peratures. The values for temperatures above 32 are the Regnault 
 Broch values; below 32 to 60 they are Marvin's values observed 
 at the Weather Bureau office, Washington City (see report of Chief 
 (Signal Officer for the year 1891). 
 
 TABLE V. ABSOLUTE HUMIDITY. 
 
 Table V gives the weight of vapor contained in the air per cubic 
 foot of air when saturated at different temperatures. 
 
 At a temperature of 43, for instance, when saturated, the weight 
 of vapor contained is 3.177 grains of water. The weight of vapor 
 contained in the air at different vapor pressures is nearly propor- 
 tional to the pressures. 
 
 TABLE VI. REDUCTION OF BAROMETER TO 32. 
 
 To reduce the barometer reading to the temperature of 32, enter 
 Table VI with the observed reading and the temperature as shown 
 by the attached thermometer. For example, suppose the reading is 
 28.50 and the attached thermometer 73, the reduction is 0.114, or 
 that amount is to be subtracted from the reading to give the pressure 
 for the temperature of the instrument at 32, 
 
 The reduction is additive below 29 and subtractive above. 
 
 TABLE VII. REDUCTION OF BAROMETER TO SEA LEVEL. 
 
 Table VII gives the approximate reduction to be applied to an 
 observation of pressure to reduce it to sea level. The following 
 example will show its use: Suppose the height of the station is 670 
 feet, and the temperature of the outside air obtained from the dry bulb 
 thermometer at the time of the observation is 45, then the reduction 
 would be .737 or .74; this amount is to be added to the observed ba- 
 rometer reading to reduce it to sea level. In using the table, observ- 
 ers should construct one in manuscript, after learning the height of 
 the station; this should be carried out to every degree of air tem- 
 perature for the height of the station as found in the left-hand 
 column. 
 
71 
 
 TABLE I. Temperature of the dew point, in degrees Fahrenheit. 
 
 ^ 
 
 Difference between the dry and wet thermometers (t t'). 
 
 
 JS 
 
 
 
 t 
 
 0.2 
 
 0.4 
 
 0.6 
 
 0.8 
 
 to.0 
 
 10.2 
 
 10.4 
 
 10.6 
 
 10.8 
 
 2.0 
 
 20.2 
 
 2.4 
 
 20.6 
 
 b 
 
 40 
 
 52 
 
 
 
 
 
 
 
 
 
 
 9 
 
 (t-f) 
 
 40 
 
 39 
 
 50 
 
 
 
 
 
 
 
 
 
 
 ~ 
 
 
 39 
 
 38 
 37 
 
 49 
 
 48 
 
 
 
 
 
 
 
 
 
 
 
 
 001 
 
 0.2 
 
 38 
 
 37 
 
 36 
 
 46 
 
 
 
 
 
 
 
 
 
 
 "* 
 
 
 
 36 
 
 35 
 
 44 
 
 
 
 
 
 
 
 
 
 
 50 
 
 60 
 
 
 35 
 
 34 
 
 43 
 
 58 
 
 
 
 
 
 
 
 
 
 49 
 
 58 
 
 
 -34 
 
 33 
 
 42 
 
 55 
 
 
 
 
 
 
 
 
 
 48 
 
 56 
 
 
 33 
 
 32 
 
 40 
 
 52 
 
 
 
 
 
 
 
 
 
 47 
 
 54 
 
 
 32 
 
 -31 
 
 38 
 
 49 
 
 
 
 
 
 
 
 
 
 46 
 
 53 
 
 
 31 
 
 30 
 
 36 
 
 47 
 
 
 
 
 
 
 
 
 
 45 
 
 51 
 
 
 30 
 
 29 
 
 35 
 
 44 
 
 
 
 
 
 
 
 
 
 44 
 
 50 
 
 60 
 
 
 28 
 
 33 
 
 42 
 
 56 
 
 
 
 
 
 
 
 
 43 
 
 49 
 
 58 
 
 28 
 
 27 
 
 32 
 
 -40 -52 
 
 
 
 
 
 
 
 
 42 
 
 48 
 
 56 
 
 27 
 
 26 
 
 30 
 
 -37 
 
 48 
 
 
 
 
 
 
 
 
 -41 
 
 -46 
 
 54 
 
 26 
 
 25 
 
 29 
 
 35 
 
 -45 
 
 
 
 
 
 
 
 
 40 
 
 45 
 
 52 
 
 25 
 
 24 
 23 
 
 -28 | -34 
 27 32 
 
 43 
 40 
 
 58 
 53 
 
 
 
 
 
 
 
 39 
 38 
 
 44 
 43 
 
 50 
 -49 
 
 24 
 23 
 
 22 
 
 26 ! 30 
 
 37 
 
 49 
 
 
 
 
 
 
 
 -37 
 
 42 
 
 48 
 
 22 
 
 21 
 
 25 29 
 
 35 
 
 45 
 
 
 
 
 
 
 
 36 
 
 41 
 
 46 
 
 21 
 
 20 
 
 23 28 
 
 33 
 
 41 
 
 55 
 
 
 
 
 
 
 35 
 
 39 
 
 44 
 
 20 
 
 19 
 
 18 
 
 -22 
 21 
 
 26 
 25 
 
 31 
 
 29 
 
 38 
 35 
 
 50 
 45 
 
 
 
 
 
 
 34 
 
 33 
 
 38 
 37 
 
 43 
 42 
 
 19 
 18 
 
 17 
 
 <20 
 
 23 
 
 27 
 
 3-2 
 
 41 
 
 55 
 
 
 
 
 
 32 
 
 35 
 
 40 
 
 17 
 
 16 
 
 19 
 
 22 
 
 26 
 
 30 
 
 37 
 
 49 
 
 
 
 
 
 31 
 
 34 
 
 38 
 
 16 
 
 15 
 14 
 
 17 
 16 
 
 20 
 19 
 
 24 
 
 22 
 
 -28 
 -26 
 
 -34 
 31 
 
 44 
 39 
 
 52 
 
 
 
 
 30 
 
 33 
 
 36 
 
 15 
 14 
 
 13 
 12 
 
 15 
 14 
 
 18 
 17 
 
 21 
 20 
 
 25 
 23 
 
 29 
 
 27 
 
 35 
 
 :tt 
 
 46 
 41 
 
 55 
 
 
 
 
 -13 
 
 12 
 
 11 
 
 13 
 
 16 
 
 18 
 
 21 
 
 25 
 
 30 
 
 36 
 
 48 
 
 
 
 
 11 
 
 10 
 g 
 
 12 
 11 
 
 14 
 13 
 
 17 
 15 
 
 20 
 18 
 
 23 
 21 
 
 27 
 25 
 
 33 
 30 
 
 42 
 37 
 
 58 
 48 
 
 
 
 10 
 9 
 
 8 
 
 - 7 
 6 
 
 10 
 
 9 
 
 8 
 
 12 
 11 
 
 10 
 
 14 
 -13 
 
 12 
 
 17 
 15 
 14 
 
 20 
 
 18 
 16 
 
 23 
 
 *>"! 
 
 19 
 
 27 
 25 
 -23 
 
 33 
 
 30 
 
 27 
 
 42 
 36 
 32 
 
 58 
 48 
 41 
 
 56 
 
 
 
 8 
 
 - 7 
 6 
 
 K 
 
 7 
 
 8 
 
 10 
 
 12 
 
 15 
 
 17 
 
 21 
 
 24 
 
 29 
 
 35 
 
 47 
 
 
 
 5 
 
 
 
 7 
 
 9 
 
 11 
 
 13 
 
 16 
 
 19 
 
 22 
 
 26 
 
 31 
 
 39 
 
 54 
 
 
 4 
 
 ~~ 
 
 4 
 
 g 
 
 8 
 
 10 
 
 12 
 
 14 
 
 17 
 
 20 
 
 23 
 
 28 
 
 33 
 
 44 
 
 
 8 
 
 
 
 3 
 
 5 
 
 6 
 
 8 
 
 10 
 
 12 
 
 15 
 
 18 
 
 21 
 
 24 
 
 29 
 
 36 
 
 48 
 
 2 
 
 L 
 
 i 
 
 2 
 
 4 
 
 5 
 
 7 
 
 9 
 
 11 
 
 13 
 
 16 
 
 18 
 
 22 
 
 26 
 
 31 
 
 39 
 
 1 
 
 
 1 
 
 3 
 
 4 
 
 6 
 
 7 
 
 9 
 
 11 
 
 14 
 
 16 
 
 19 
 
 -23 
 
 27 
 
 33 
 
 
 
 + i 
 
 1 
 
 
 
 1 1 
 
 2 
 1 
 
 3 
 
 2 
 
 4 
 3 
 
 6 
 5 
 
 8 
 6 
 
 10 
 8 
 
 12 
 10 
 
 14 
 
 12 
 
 17 
 15 
 
 20 
 17 
 
 24 
 21 
 
 28 
 25 
 
 + 1 
 
 - 
 
 
 
 1 
 
 2 
 
 3 
 
 . 5 
 
 _ 7 
 
 8 
 
 10 
 
 13 
 
 15 
 
 -18 
 
 21 
 
 3 
 
 4 
 
 3 
 
 + l 
 
 + 2 
 
 
 
 1 
 
 2 
 
 4 
 
 5 
 
 7 
 
 9 
 
 11 
 
 13 
 
 16 
 
 19 
 
 4 
 
 5 
 
 4 
 
 3 
 
 + 1 
 
 
 
 1 
 
 2 
 
 4 
 
 5 
 
 7 
 
 9 
 
 11 
 
 14 
 
 12 
 
 16 
 14 
 
 5 
 6 
 
 6 
 7 
 
 5 
 g 
 
 4 
 
 5 
 
 3 
 4 
 
 + 1 
 3 
 
 
 + l 
 
 
 
 1 
 
 3 
 
 4 
 
 6 
 
 8 
 
 10 
 
 12 
 
 7 
 
 g 
 
 7 
 
 6 
 
 5 
 
 4 
 
 3 
 
 + 1 
 
 
 
 1 
 
 3 
 
 4 
 
 6 
 
 8 
 
 10 
 
 8 
 
 9 
 
 8 
 
 7 
 
 6 
 
 5 
 
 4 
 
 3 
 
 + 1 
 
 
 
 - 1 
 
 3 
 
 4 
 
 6 
 
 8 
 
 9 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 5 
 
 4 
 
 3 
 
 + 1 
 
 
 
 1 
 
 3 
 
 4 
 
 6 
 
 10 
 
 11 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 5 
 
 4 
 
 3 
 
 + 2 
 
 
 
 1 
 
 3 
 
 4 
 
 11 
 
 12 
 
 11 
 
 10 
 
 9 
 
 9 
 
 8 
 
 7 
 
 5 
 
 4 
 
 3 
 
 + 2 
 
 
 
 - 1 
 
 2 
 
 12 
 
 13 
 
 12 
 
 11 
 
 11 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 5 
 
 3 
 
 + 2 
 
 + 1 
 
 1 
 
 13 
 
 14 
 
 13 
 
 12 
 
 12 
 
 11 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 5 
 
 4 
 
 2 
 
 + 1 
 
 14 
 
 15 
 
 14 
 
 13 
 
 13 
 
 12 
 
 11 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 5 
 
 4 
 
 3 
 
 15 
 
 16 
 
 15 
 
 15 
 
 14 
 
 13 
 
 12 
 
 11 
 
 10 
 
 10 
 
 9 
 
 8 
 
 7 
 
 5 
 
 4 
 
 16 
 
 17 
 
 16 
 
 16 
 
 15 
 
 14 
 
 13 
 
 12 
 
 12 
 
 11 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 17 
 
 18 
 
 17 
 
 17 
 
 16 
 
 15 
 
 14 
 
 14 
 
 13 
 
 12 
 
 11 
 
 10 
 
 9 
 
 8 
 
 7 
 
 18 
 
 19 
 
 18 
 
 18 
 
 17 
 
 16 
 
 15 
 
 15 
 
 14 
 
 13 
 
 12 
 
 11 
 
 10 
 
 10 
 
 9 
 
 19 
 
 20 
 
 19 
 
 19 
 
 18 
 
 17 
 
 17 
 
 16 
 
 15 
 
 14 
 
 13 
 
 13 
 
 12 
 
 11 
 
 10 
 
 20 
 
 t. 
 
 0.2 
 
 0.4 
 
 0.6 
 
 0.8 
 
 10 
 
 10.2 
 
 10.4 
 
 10.6 
 
 10.8 
 
 2.0 
 
 2. 2 
 
 2.4 
 
 2. 6 
 
 t. 
 
 Point. 
 
72 
 
 TABLE I. Temperature of the dew point, in degrees Fahrenheit. 
 
 k 
 
 0" 
 
 Difference between the dry and wet thermometers (tf). 
 
 * 
 
 I 
 
 2. 6 
 
 2. 8 
 
 3.0 
 
 3. 2 
 
 3. 4 
 
 3. 6 
 
 3. 8 
 
 4.0 
 
 4. 2 
 
 4. 4 
 
 fc 
 
 g, 
 
 2 
 
 48 
 
 
 
 
 
 
 
 
 
 
 2 
 
 1 
 
 39 
 
 54 
 
 
 
 
 
 
 
 
 
 1 
 
 
 
 33 
 
 43 
 
 
 
 
 
 
 
 
 
 
 
 + 1 
 
 28 
 
 35 
 
 -46 
 
 
 
 
 
 
 
 
 + 1 
 
 I 2 
 
 25 
 
 30 
 
 37 
 
 50 
 
 
 
 
 
 
 
 2 
 
 3 
 
 21 
 
 26 
 
 31 
 
 39 
 
 54 
 
 
 
 
 
 
 3 
 
 4 
 
 19 
 
 22 
 
 27 
 
 32 
 
 42 
 
 60 
 
 
 
 
 
 4 
 
 5 
 
 16 
 
 19 
 
 23 
 
 28 
 
 34 
 
 45 
 
 
 
 
 
 5 
 
 G 
 
 14 
 
 17 
 
 20 
 
 24 
 
 29 
 
 35 
 
 47 
 
 
 
 
 6 
 
 7 
 
 12 
 
 14 
 
 17 
 
 20 
 
 24 
 
 29 
 
 37 
 
 50 
 
 
 
 7 
 
 8 
 
 10 
 
 12 
 
 15 
 
 17 
 
 21 
 
 25 
 
 30 
 
 38 
 
 53 
 
 
 8 
 
 9 
 
 8 
 
 10 
 
 -12 
 
 15 
 
 18 
 
 21 
 
 25 
 
 31 
 
 39 
 
 55 
 
 9 
 
 10 
 
 6 
 
 8 
 
 10 
 
 12 
 
 15 
 
 18 
 
 21 
 
 26 
 
 ^31 
 
 40 
 
 10 
 
 11 
 
 _ 4 
 
 6 
 
 8 
 
 10 
 
 12 
 
 15 
 
 18 
 
 21 
 
 26 
 
 31 
 
 11 
 
 12 
 
 2 
 
 4 
 
 6 
 
 8 
 
 -10 
 
 12 
 
 15 
 
 18 
 
 21 
 
 26 
 
 12 
 
 13 
 
 _ 1 
 
 2 
 
 4 
 
 5 
 
 7 
 
 9 
 
 12 
 
 14 
 
 17 
 
 21 
 
 13 
 
 14 
 
 + 1 
 
 
 
 2 
 
 3 
 
 5 
 
 7 
 
 9 
 
 11 
 
 14 
 
 17 
 
 14 
 
 15 
 
 3 
 
 + 1 
 
 
 
 2 
 
 3 
 
 5 
 
 7 
 
 9 
 
 11 
 
 14 
 
 15 
 
 16 
 
 4 
 
 3 
 
 + 2 
 
 
 
 1 
 
 3 
 
 4 
 
 6 
 
 8 
 
 10 
 
 16 
 
 17 
 
 6 
 
 5 
 
 3 
 
 + 2 
 
 + 1 
 
 1 
 
 2 
 
 _ 4 
 
 6 
 
 8 
 
 17 
 
 18 
 
 7 
 
 6 
 
 5 
 
 4 
 
 2 
 
 + 1 
 
 
 
 2 
 
 3 
 
 5 
 
 18 
 
 19 
 
 9 
 
 8 
 
 7 
 
 5 
 
 4 
 
 3 
 
 + 1 
 
 
 
 l 
 
 3 
 
 19 
 
 20 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 5 
 
 3 
 
 + 2 
 
 + 1 
 
 1 
 
 20 
 
 t. 
 
 2.G 
 
 2. 8 
 
 3.0 
 
 3. 2 
 
 3. 4 
 
 3. 6 
 
 3. 8 
 
 4.0 
 
 4. 2 
 
 4. 4 
 
 t. 
 
 t. 
 
 4. 6 
 
 4. 8 
 
 5.0 
 
 5. 2 
 
 5. 4 
 
 5. 6 
 
 5. 8 
 
 6. 
 
 G.2 
 
 G.4 
 
 t. 
 
 8 
 
 
 
 
 
 
 
 
 
 
 
 8 
 
 9 
 
 
 
 
 
 
 
 
 
 
 
 9 
 
 10 
 
 57 
 
 
 
 
 
 
 
 
 
 
 10 
 
 11 
 
 41 
 
 60 
 
 
 
 
 
 
 
 
 
 11 
 
 12 
 
 31 
 
 41 
 
 59 
 
 
 
 
 
 
 
 
 12 
 
 13 
 
 -25 
 
 31 
 
 40 
 
 58 
 
 
 
 
 
 
 
 13 
 
 14 
 
 20 
 
 25 
 
 30 
 
 39 
 
 56 
 
 
 
 
 
 
 14 
 
 15 
 
 16 
 
 20 
 
 24 
 
 30 
 
 38 
 
 53 
 
 
 
 
 
 15 
 
 16 
 
 13 
 
 16 
 
 19 
 
 23 
 
 28 
 
 36 
 
 50 
 
 
 
 
 16 
 
 17 
 
 10 
 
 12 
 
 -15 
 
 18 
 
 22 
 
 27 
 
 34 
 
 47 
 
 
 
 17 
 
 18 
 
 7 
 
 9 
 
 [2 
 
 14 
 
 17 
 
 21 
 
 26 
 
 32 
 
 44 
 
 
 18 
 
 19 
 
 - 5 
 
 7 
 
 9 
 
 11 
 
 14 
 
 17 
 
 20 
 
 25 
 
 30 
 
 40 
 
 19 
 
 20 
 
 2 
 
 4 
 
 6 
 
 8 
 
 10 
 
 13 
 
 16 
 
 19 
 
 is 
 
 29 
 
 20 
 
 t. 
 
 4. 6 
 
 4. 8 
 
 5.0 
 
 5. 2 
 
 5. 4 
 
 5. 6 
 
 5. 8 
 
 6.0 
 
 6. 2 
 
 6. 4 
 
 t. 
 
73 
 
 TABLE I Temperature of the dew point, in degrees Fahrenheit. 
 
 1 
 
 1 
 
 Difference between the dry and wet thermometers (t t'). 
 
 t 
 (Dry ther.) 
 
 0.5 
 
 1.0 
 
 1.5 
 
 2.0 
 
 2. 5 
 
 3.0 
 
 3. 5 
 
 4.0 
 
 4. 5 
 
 5.0 
 
 5. 5 
 
 6.0 
 
 20 
 
 18 
 
 17 
 
 15 
 
 13 
 
 10 
 
 8 
 
 5 
 
 2 
 
 2 
 
 6 
 
 -12 
 
 19 
 
 20 
 
 21 
 
 19 
 
 18 
 
 16 
 
 14 
 
 12 
 
 9 
 
 7 
 
 4 
 
 
 
 4 
 
 8 
 
 15 
 
 21 
 
 22 
 
 20 
 
 19 
 
 17 
 
 15 
 
 13 
 
 11 
 
 8 
 
 6 
 
 +2 
 
 1 
 
 6 
 
 11 
 
 22 
 
 23 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 12 
 
 10 
 
 7 
 
 4 
 
 +1 
 
 3 
 
 8 
 
 23 
 
 24 
 
 23 
 
 21 
 
 19 
 
 18 
 
 16 
 
 14 
 
 11 
 
 9 
 
 6 
 
 3 
 
 1 
 
 5 
 
 24 
 
 25 
 
 24 
 
 22 
 
 21 
 
 19 
 
 17 
 
 15 
 
 13 
 
 11 
 
 8 
 
 5 
 
 + 2 
 
 2 
 
 26 
 
 26 
 
 25 
 
 23 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 12 
 
 10 
 
 7 
 
 4 
 
 
 
 26 
 
 27 
 
 26 
 
 24 
 
 23 
 
 21 
 
 20 
 
 18 
 
 16 
 
 14 
 
 11 
 
 9 
 
 6 
 
 + 3 
 
 27 
 
 28 
 
 27 
 
 25 
 
 24 
 
 22 
 
 21 
 
 19 
 
 17 
 
 15 
 
 13 
 
 11 
 
 8 
 
 5 
 
 28 
 
 29 
 
 28 
 
 26 
 
 25 
 
 24 
 
 22 
 
 20 
 
 19 
 
 17 
 
 14 
 
 12 
 
 10 
 
 7 
 
 29 
 
 30 
 
 29 
 
 27 
 
 26 
 
 25 
 
 23 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 11 
 
 9 
 
 30 
 
 31 
 
 30 
 
 29 
 
 27 
 
 26 
 
 24 
 
 23 
 
 21 
 
 19 
 
 18 
 
 15 
 
 13 
 
 11 
 
 31 
 
 32 
 
 31 
 
 30 
 
 28 
 
 27 
 
 26 
 
 24 
 
 22 
 
 21 
 
 19 
 
 17 
 
 15 
 
 13 
 
 32 
 
 33 
 
 31 
 
 31 
 
 29 
 
 28 
 
 26 
 
 25 
 
 23 
 
 22 
 
 19 
 
 18 
 
 16 
 
 14 
 
 33 
 
 34 
 
 32 
 
 32 
 
 30 
 
 29 
 
 27 
 
 26 
 
 24 
 
 24 
 
 21 
 
 20 
 
 18 
 
 16 
 
 34 
 
 35 
 
 33 
 
 32 
 
 31 
 
 30 
 
 29 
 
 28 
 
 26 
 
 25 
 
 23 
 
 22 
 
 20 
 
 18 
 
 35 
 
 36 
 
 35 
 
 34 
 
 32 
 
 31 
 
 30 
 
 29 
 
 27 
 
 26 
 
 24 
 
 23 
 
 21 
 
 19 
 
 36 
 
 37 
 
 36 
 
 35 
 
 33 
 
 32 
 
 31 
 
 30 
 
 28 
 
 27 
 
 26 
 
 24 
 
 22 
 
 21 
 
 37 
 
 38 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 31 
 
 30 
 
 28 
 
 27 
 
 26 
 
 24 
 
 22 
 
 38 
 
 39 
 
 38 
 
 37 
 
 35 
 
 34 
 
 33 
 
 32 
 
 30 
 
 29 
 
 28 
 
 27 
 
 25 
 
 24 
 
 39 
 
 40 
 
 39 
 
 38 
 
 36 
 
 35 
 
 34 
 
 33 
 
 31 
 
 30 
 
 29 
 
 28 
 
 26 
 
 25 
 
 40 
 
 41 
 
 40 
 
 39 
 
 37 
 
 3(5 
 
 35 
 
 34 
 
 32 
 
 32 
 
 30 
 
 29 
 
 28 
 
 26 
 
 41 
 
 42 
 
 41 
 
 40 
 
 39 
 
 38 
 
 36 
 
 35 
 
 34 
 
 33 
 
 31 
 
 30 
 
 29 
 
 27 
 
 42 
 
 43 
 
 42 
 
 41 
 
 40 
 
 39 
 
 37 
 
 36 
 
 35 
 
 34 
 
 32 
 
 31 
 
 30 
 
 29 
 
 43 
 
 44 
 
 43 
 
 42 
 
 41 
 
 40 
 
 38 
 
 37 
 
 36 
 
 35 
 
 33 
 
 32 
 
 31 
 
 30 
 
 44 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 31 
 
 45 
 
 46 
 47 
 
 45 
 46 
 
 44 
 45 
 
 43 
 44 
 
 42 
 43 
 
 41 
 
 42 
 
 40 
 41 
 
 38 
 40 
 
 37 
 39 
 
 36 
 37 
 
 35 
 36 
 
 33 
 34 
 
 32 
 33 
 
 t? 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 40 
 
 38 
 
 37 
 
 36 
 
 35 
 
 48 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 39 
 
 38 
 
 a7 
 
 36 
 
 49 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 40 
 
 38 
 
 37 
 
 50 
 
 51 
 
 . 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 39 
 
 38 
 
 51 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 40 
 
 52 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 53 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 50 
 
 49 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 54 
 
 55 
 
 54 
 
 53 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 44 
 
 43 
 
 55 
 
 56 
 
 55 
 
 54 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 45 
 
 44 
 
 56 
 
 57 
 
 56 
 
 55 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 57 
 
 58 
 
 57 
 
 56 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 58 
 
 59 
 
 58 
 
 57 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 59 
 
 60 
 
 59 
 
 58 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 60 
 
 61 
 
 60 
 
 59 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 61 
 
 62 
 
 61 
 
 60 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 52 
 
 62 
 
 63 
 
 62 
 
 61 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 55 
 
 54 
 
 53 
 
 63 
 
 64 
 
 63 
 
 62 
 
 62 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 56 
 
 55 
 
 54 
 
 64 
 
 65 
 
 04 
 
 63 
 
 63 
 
 62 
 
 61 
 
 60 
 
 59 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 65 
 
 66 
 
 65 
 
 64 
 
 64 
 
 63 
 
 62 
 
 61 
 
 60 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 66 
 
 67 
 
 67 
 
 615 
 
 65 
 
 64 
 
 63 
 
 62 
 
 61 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 67 
 
 68 
 
 68 
 
 67 
 
 66 
 
 65 
 
 64 
 
 63 
 
 62 
 
 62 
 
 61 
 
 60 
 
 59 
 
 58 
 
 68 
 
 69 
 
 69 
 
 68 
 
 67 
 
 66 
 
 65 
 
 64 
 
 63 
 
 63 
 
 62 
 
 61 
 
 60 
 
 59 
 
 69 
 
 70 
 
 70 
 
 69 
 
 68 
 
 67 
 
 67 
 
 66 
 
 65 
 
 64 
 
 63 
 
 62 
 
 61 
 
 61 
 
 70 
 
 71 
 
 71 
 
 70 
 
 69 
 
 68 
 
 68 
 
 67 
 
 66 
 
 65 
 
 64 
 
 63 
 
 62 
 
 62 
 
 71 
 
 72 
 
 72 
 
 71 
 
 70 
 
 69 
 
 69 
 
 68 
 
 67 
 
 66 
 
 65 
 
 64 
 
 63 
 
 63 
 
 72 
 
 73 
 
 73 
 
 72 
 
 71 
 
 70 
 
 70 
 
 69 
 
 68 
 
 67 
 
 66 
 
 66 
 
 65 
 
 64 
 
 73 
 
 74 
 
 74 
 
 73 
 
 72 
 
 71 
 
 71 
 
 70 
 
 69 
 
 68 
 
 67 
 
 67 
 
 66 
 
 65 
 
 74 
 
 75 
 
 75 
 
 74 
 
 73 
 
 72 
 
 72 
 
 71 
 
 70 
 
 69 
 
 68 
 
 68 
 
 67 
 
 66 
 
 75 
 
 70 
 
 76 
 
 75 
 
 74 
 
 73 
 
 73 
 
 72 
 
 71 
 
 70 
 
 69 
 
 69 
 
 68 
 
 67 
 
 76 
 
 77 
 
 77 
 
 76 
 
 75 
 
 74 
 
 74 
 
 73 
 
 72 
 
 71- 
 
 70 
 
 70 
 
 69 
 
 68 
 
 77 
 
 78 
 
 78 
 
 77 
 
 76 
 
 75 
 
 75 
 
 74 
 
 73 
 
 72 
 
 71 
 
 71 
 
 70 
 
 69 
 
 78 
 
 79 
 
 79 
 
 78 
 
 77 
 
 76 
 
 76 
 
 75 
 
 74 
 
 73 
 
 72 
 
 72 
 
 71 
 
 70 
 
 79 
 
 80 
 
 80 
 
 79 
 
 78 
 
 77 
 
 77 
 
 76 
 
 75 
 
 74 
 
 73 
 
 73 
 
 72 
 
 72 
 
 80 
 
 t. 
 
 0.5 
 
 1.0 
 
 1.5 
 
 2.0 
 
 2. 5 
 
 3.0 
 
 3. 5 
 
 4.0 
 
 40.5 
 
 5.0 
 
 5.5 
 
 6.0 
 
 <. 
 
74 
 
 TABLE I. Temperature of the dew point, in degrees Fahrenheit. 
 
 t 
 (Dry ther.) 
 
 Difference between the dry and wet thermometers (< t'). 
 
 t 
 (Dry ther.) 
 
 6.0 
 
 6 3 .5 
 
 7.0 
 
 7. 5 
 
 8.0 
 
 8. 5 
 
 9.0 
 
 9. 5 
 
 10. 
 
 10. 5 
 
 11. 
 
 11. 5 
 
 12. 
 
 19 
 
 25 
 
 
 
 
 
 
 
 
 
 
 
 
 
 19 
 
 20 
 
 19 
 
 32 
 
 
 
 
 
 
 
 
 
 
 
 
 20 
 
 21 
 
 15 
 
 24 
 
 -47 
 
 
 
 
 
 
 
 
 
 
 
 21 
 
 22 
 
 -11 
 
 19 
 
 -31 
 
 
 
 
 
 
 
 
 
 
 
 22 
 
 23 
 
 8 
 
 14 
 
 -24 
 
 45 
 
 
 
 
 
 
 
 
 
 
 23 
 
 24 
 
 5 
 
 -10 
 
 -18 
 
 30 
 
 
 
 
 
 
 
 
 
 
 24 
 
 25 
 
 - 2 
 
 7 
 
 -13 
 
 22 
 
 42 
 
 
 
 
 
 
 
 
 
 25 
 
 26 
 
 
 
 4 
 
 9 
 
 -17 
 
 28 
 
 
 
 
 
 
 
 
 
 26 
 
 27 
 
 + 3 
 
 1 
 
 - 6 
 
 -12 
 
 -20 
 
 37 
 
 
 
 
 
 
 
 
 27 
 
 28 
 
 5 
 
 + 1 
 
 O 
 
 8 
 
 15 
 
 25 
 
 54 
 
 
 
 
 
 
 
 28 
 
 29 
 
 7 
 
 4 
 
 
 
 4 
 
 -10 
 
 -18 
 
 -32 
 
 
 
 
 
 
 
 29 
 
 30 
 
 9 
 
 6 
 
 + 2 
 
 - 2 
 
 6 
 
 -13 
 
 -22 
 
 43 
 
 
 
 
 
 
 30 
 
 31 
 
 11 
 
 8 
 
 5 
 
 + 1 
 
 3 
 
 8 
 
 -15 
 
 -27 
 
 
 
 
 
 
 31 
 
 32 
 
 13 
 
 10 
 
 7 
 
 4 
 
 
 
 4 
 
 10 
 
 -18 
 
 33 
 
 
 
 
 
 32 
 
 33 
 
 14 
 
 12 
 
 9 
 
 6 
 
 + 3 
 
 1 
 
 6 
 
 -12 
 
 -22 
 
 44 
 
 
 
 
 33 
 
 34 
 
 16 
 
 14 
 
 11 
 
 8 
 
 6 
 
 + 2 
 
 2 
 
 Q 
 
 -15 
 
 -27 
 
 
 
 
 34 
 
 35 
 
 18 
 
 15 
 
 13 
 
 10 
 
 8 
 
 5 
 
 + 1 
 
 - 4 
 
 - 9 
 
 18 
 
 32 
 
 
 
 35 
 
 36 
 
 19 
 
 17 
 
 15 
 
 12 
 
 10 
 
 8 
 
 4 
 
 
 
 5 
 
 12 
 
 -20 
 
 42 
 
 
 36 
 
 37 
 
 21 
 
 19 
 
 17 
 
 14 
 
 12 
 
 9 
 
 6 
 
 + 3 
 
 - 2 
 
 6 
 
 14 
 
 -25 
 
 -52 
 
 37 
 
 38 
 
 22 
 
 20 
 
 19 
 
 16 
 
 14 
 
 11 
 
 9 
 
 6 
 
 + 2 
 
 2 
 
 8 
 
 -16 
 
 -29 
 
 38 
 
 39 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 11 
 
 8 
 
 5 
 
 + 1 
 
 A 
 
 -10 
 
 -18 
 
 3U 
 
 40 
 
 25 
 
 23 
 
 22 
 
 20 
 
 18 
 
 16 
 
 13 
 
 11 
 
 8 
 
 4 
 
 
 
 - 5 
 
 -12 
 
 40 
 
 41 
 
 20 
 
 25 
 
 23 
 
 21 
 
 20 
 
 17 
 
 15 
 
 13 
 
 10 
 
 7 
 
 + 4 
 
 1 
 
 6 
 
 41 
 
 42 
 
 27 
 
 26 
 
 24 
 
 23 
 
 21 
 
 19 
 
 18 
 
 15 
 
 12 
 
 10 
 
 7 
 
 + 3 
 
 - 2 
 
 42 
 
 43 
 
 29 
 
 27 
 
 26 
 
 24 
 
 23 
 
 21 
 
 19 
 
 17 
 
 14 
 
 12 
 
 9 
 
 6 
 
 + 2 
 
 43 
 
 44 
 
 30 
 
 28 
 
 27 
 
 20 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 12 
 
 9 
 
 6 
 
 44 
 
 45 
 
 31 
 
 30 
 
 28 
 
 27 
 
 25 
 
 24 
 
 22 
 
 20 
 
 IS 
 
 16 
 
 13 
 
 11 
 
 8 
 
 45 
 
 46 
 
 32 
 
 31 
 
 30 
 
 28 
 
 27 
 
 25 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 13 
 
 11 
 
 46 
 
 47 
 
 33 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 25 
 
 23 
 
 22 
 
 20 
 
 18 
 
 15 
 
 13 
 
 47 
 
 48 
 
 35 
 
 33 
 
 32 
 
 30 
 
 29 
 
 28 
 
 26 
 
 25 
 
 23 
 
 21 
 
 20 
 
 17 
 
 15 
 
 48 
 
 49 
 
 36 
 
 34 
 
 33 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 25 
 
 23 
 
 21 
 
 19 
 
 17 
 
 49 
 
 50 
 
 37 
 
 35 
 
 34 
 
 33 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 23 
 
 21 
 
 19 
 
 50 
 
 51 
 
 38 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 22 
 
 21 
 
 51 
 
 52 
 
 40 
 
 38 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 30 
 
 29 
 
 28 
 
 20 
 
 24 
 
 23 
 
 52 
 
 53 
 
 41 
 
 39 
 
 38 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 30 
 
 29 
 
 28 
 
 20 
 
 24 
 
 53 
 
 54 
 
 42 
 
 41 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 30 
 
 29 
 
 27 
 
 26 
 
 54 
 
 55 
 
 43 
 
 42 
 
 41 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 30 
 
 29 
 
 28 
 
 55 
 
 50 
 
 44 
 
 43 
 
 42 
 
 41 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 30 
 
 29 
 
 56 
 
 57 
 
 46 
 
 45 
 
 44 
 
 42 
 
 41 
 
 40 
 
 39 
 
 37 
 
 36 
 
 35 
 
 33 
 
 32 
 
 30 
 
 57 
 
 58 
 
 47 
 
 46 
 
 45 
 
 44 
 
 42 
 
 41 
 
 40 
 
 39 
 
 37 
 
 36 
 
 35 
 
 33 
 
 32 
 
 58 
 
 59 
 
 48 
 
 47 
 
 40 
 
 45 
 
 44 
 
 43 
 
 41 
 
 40 
 
 39 
 
 38 
 
 36 
 
 35 
 
 33 
 
 59 
 
 60 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 41 
 
 40 
 
 39 
 
 38 
 
 36 
 
 35 
 
 60 
 
 61 
 
 50 
 
 49 
 
 48 
 
 47 
 
 40 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 39 
 
 38 
 
 36 
 
 01 
 
 62 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 39 
 
 38 
 
 62 
 
 63 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 45 
 
 44 
 
 43 
 
 42 
 
 41 
 
 39 
 
 63 
 
 64 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 43 
 
 42 
 
 41 
 
 64 
 
 65 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 43 
 
 42 
 
 65 
 
 66 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 44 
 
 66 
 
 67 
 
 57 
 
 56 
 
 55 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 48 
 
 47 
 
 46 
 
 45 
 
 67 
 
 68 
 
 58 
 
 57 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 47 
 
 46 
 
 68 
 
 69 
 
 59 
 
 58 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 69 
 
 70 
 
 Gl 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 70 
 
 71 
 
 62 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 71 
 
 72 
 
 63 
 
 62 
 
 61 
 
 60 
 
 59 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 72 
 
 73 
 
 64 
 
 63 
 
 62 
 
 62 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 73 
 
 74 
 
 65 
 
 64 
 
 63 
 
 63 
 
 62 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 74 
 
 75 
 
 66 
 
 65 
 
 64 
 
 64 
 
 63 
 
 62 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 56 
 
 75 
 
 76 
 
 67 
 
 66 
 
 65 
 
 65 
 
 64 
 
 63 
 
 62 
 
 61 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 76 
 
 77 
 
 68 
 
 67 
 
 67 
 
 66 
 
 65 
 
 64 
 
 63 
 
 62 
 
 62 
 
 61 
 
 60 
 
 59 
 
 58 
 
 77 
 
 78 
 
 69 
 
 68 
 
 68 
 
 67 
 
 66 
 
 66 
 
 65 
 
 64 
 
 63 
 
 62 
 
 61 
 
 60 
 
 59 
 
 78 
 
 79 
 
 70 
 
 69 
 
 69 
 
 68 
 
 67 
 
 67 
 
 GO 
 
 65 
 
 64 
 
 63 
 
 62 
 
 61 
 
 61 
 
 79 
 
 80 
 
 72 
 
 71 
 
 70 
 
 09 
 
 68 
 
 68 
 
 67 
 
 66 
 
 05 
 
 64 
 
 63 
 
 62 
 
 62 
 
 80 
 
 t. 
 
 6.0 
 
 6. 5 
 
 7.0 
 
 7. 5 
 
 8.0 
 
 8. 5 
 
 9.0 
 
 9. 5 
 
 10. 
 
 10. 5 
 
 11. 
 
 11. 5 
 
 12. 
 
 /. 
 
75 
 
 TABLE I. Temperature of the dew point, in degrees Fahrenheit. 
 
 B 
 
 M 
 
 >-, 
 
 
 Difference between the dry and wet thermometers (t t?). 
 
 h 
 
 d 
 
 "| 
 
 12. 
 
 12. 5 
 
 13. 
 
 13. 5 
 
 14. 
 
 14. 5 
 
 15. 
 
 15. 5 
 
 16. 
 
 16. 5 
 
 17. 
 
 17. 5 
 
 18. 
 
 40 
 
 12 
 
 -22 
 
 44 
 
 
 
 
 
 
 
 
 
 
 
 40 
 
 41 
 
 - 6 
 
 13 
 
 25 
 
 
 
 
 
 
 
 
 
 
 
 41 
 
 42 
 
 2 
 
 n 
 
 15 
 
 28 
 
 
 
 
 
 
 
 
 
 
 42 
 
 43 
 
 + 2 
 
 3 
 
 8 
 
 17 
 
 33 
 
 
 
 
 
 
 
 
 
 43 
 
 44 
 
 6 
 
 + 1 
 
 4 
 
 10 
 
 19 
 
 40 
 
 
 
 
 
 
 
 
 44 
 
 45 
 
 8 
 
 5 
 
 
 
 4 
 
 11 
 
 22 
 
 48 
 
 
 
 
 
 
 
 45 
 
 46 
 
 11 
 
 8 
 
 + * 
 
 
 
 5 
 
 13 
 
 -24 
 
 
 
 
 
 
 
 46 
 
 47 
 
 13 
 
 10 
 
 7 
 
 + 3 
 
 1 
 
 6 
 
 14 
 
 27 
 
 
 
 
 
 
 47 
 
 48 
 
 15 
 
 12 
 
 10 
 
 6 
 
 + 2 
 
 2 
 
 8 
 
 16 
 
 30 
 
 
 
 
 
 48 
 
 49 
 
 17 
 
 14 
 
 12 
 
 9 
 
 6 
 
 + 2 
 
 3 
 
 9 
 
 -18 
 
 35 
 
 
 
 
 49 
 
 50 
 
 19 
 
 16 
 
 14 
 
 12 
 
 9 
 
 5 
 
 + 1 
 
 4 
 
 10 
 
 20 
 
 42 
 
 
 
 50 
 
 51 
 
 21 
 
 18 
 
 17 
 
 14 
 
 11 
 
 8 
 
 5 
 
 
 
 5 
 
 12 
 
 22 
 
 52 
 
 
 51 
 
 52 
 
 23 
 
 21 
 
 19 
 
 16 
 
 U 
 
 11 
 
 8 
 
 + 4 
 
 
 
 6 
 
 13 
 
 25 
 
 
 52 
 
 53 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 11 
 
 8 
 
 + 4 
 
 1 
 
 6 
 
 14 
 
 28 
 
 53 
 
 54 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 13 
 
 10 
 
 7 
 
 + 3 
 
 2 
 
 8 
 
 16 
 
 54 
 
 55 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 13 
 
 10 
 
 7 
 
 + 3 
 
 2 
 
 8 
 
 55 
 
 56 
 
 29 
 
 27 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 15 
 
 13 
 
 10 
 
 6 
 
 + 2 
 
 . 2 
 
 56 
 
 57 
 
 30 
 
 29 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 15 
 
 13 
 
 10 
 
 6 
 
 + 2 
 
 57 
 
 58 
 
 32 
 
 30 
 
 29 
 
 27 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 15 
 
 12 
 
 9 
 
 6 
 
 68 
 
 59 
 
 33 
 
 32 
 
 31 
 
 29 
 
 27 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 15 
 
 12 
 
 9 
 
 59 
 
 60 
 
 35 
 
 33 
 
 32 
 
 30 
 
 29 
 
 27 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 15 
 
 12 
 
 60 
 
 61 
 
 36 
 
 35 
 
 33 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 15 
 
 61 
 
 62 
 
 38 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 62 
 
 63 
 
 39 
 
 38 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 63 
 
 64 
 
 41 
 
 39 
 
 38 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 22 
 
 64 
 
 65 
 
 42 
 
 41 
 
 40 
 
 38 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 65 
 
 66 
 
 44 
 
 43 
 
 41 
 
 40 
 
 38 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 30 
 
 28 
 
 ' 26 
 
 66 
 
 67 
 
 45 
 
 44 
 
 43 
 
 41 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 32 
 
 31 
 
 30 
 
 28 
 
 67 
 
 68 
 
 46 
 
 45 
 
 44 
 
 43 
 
 42 
 
 40 
 
 39 
 
 38 
 
 36 
 
 34 
 
 33 
 
 31 
 
 30 
 
 68 
 
 69 
 
 48 
 
 47 
 
 46 
 
 45 
 
 43 
 
 42 
 
 40 
 
 39 
 
 38 
 
 36 
 
 34 
 
 33 
 
 32 
 
 69 
 
 70 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 43 
 
 42 
 
 41 
 
 39 
 
 38 
 
 36 
 
 35 
 
 33 
 
 70 
 
 71 
 
 51 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 43 
 
 42 
 
 41 
 
 39 
 
 38 
 
 36 
 
 35 
 
 71 
 
 72 
 
 52 
 
 51 
 
 50 
 
 49 
 
 47 
 
 46 
 
 45 
 
 44 
 
 43 
 
 41 
 
 40 
 
 38 
 
 37 
 
 72 
 
 73 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 46 
 
 45 
 
 44 
 
 43 
 
 41 
 
 40 
 
 38 
 
 73 
 
 74 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 45 
 
 44 
 
 43 
 
 41 
 
 40 
 
 74 
 
 75 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 50 
 
 49 
 
 48 
 
 47 
 
 45 
 
 44 
 
 43 
 
 42 
 
 75 
 
 76 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 50 
 
 49 
 
 48 
 
 47 
 
 46 
 
 45 
 
 43 
 
 76 
 
 77 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 4!) 
 
 48 
 
 46 
 
 45 
 
 77 
 
 78 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 49 
 
 48 
 
 47 
 
 78 
 
 79 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 
 
 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 49 
 
 48 
 
 79 
 
 80 
 
 62 
 
 61 
 
 60 
 
 59 
 
 58 
 
 57 
 
 56 55 
 
 54 
 
 53 
 
 52 
 
 51 
 
 50 
 
 80 
 
 t. 
 
 12. 
 
 12. 5 
 
 13. 
 
 13. 5 
 
 14. 
 
 14. 5 
 
 15. 
 
 15. 5 
 
 16. 
 
 16. 5 
 
 17. 
 
 17. 5 
 
 18. 
 
 I. 
 
76 
 
 TABLE I. Temperature of the dew point, in degrees Fahrenheit. 
 
 t 
 (Dryther.) 
 
 Difference between the dry and wet thermometers (t t'). 
 
 2 
 
 >-> 
 
 Q_ 
 
 18.0 
 
 19.0 
 
 20.0 
 
 21.0 
 
 22. 
 
 23.0 
 
 24.0 
 
 25.0 
 
 26.0 
 
 27.0 
 
 28.0 
 
 29.0 
 
 30. 
 
 55 
 
 -8 
 
 
 
 
 
 
 
 
 
 
 
 
 
 55 
 
 66 
 
 2 
 
 19 
 
 
 
 
 
 
 
 
 
 
 
 
 56 
 
 57 
 
 +2 
 
 10 
 
 48 
 
 
 
 
 
 
 
 
 
 
 
 57 
 
 58 
 
 6 
 
 3 
 
 22 
 
 
 
 
 
 
 
 
 
 
 
 58 
 
 59 
 
 9 
 
 + 1 
 
 12 
 
 
 
 
 
 
 
 
 
 
 
 59 
 
 60 
 
 12 
 
 5 
 
 5 
 
 -25 
 
 
 
 
 
 
 
 
 
 
 60 
 
 61 
 
 15 
 
 9 
 
 
 
 14 
 
 
 
 
 
 
 
 
 
 
 61 
 
 62 
 
 18 
 
 12 
 
 4- 5 
 
 6 
 
 28 
 
 
 
 
 
 
 
 
 
 62 
 
 68 
 
 20 
 
 15 
 
 9 
 
 
 
 14 
 
 
 
 
 
 
 
 
 63 
 
 64 
 
 22 
 
 18 
 
 12 
 
 + 4 
 
 6 
 
 32 
 
 
 
 
 
 
 
 64 
 
 65 
 
 24 
 
 20 
 
 15 
 
 9 
 
 
 
 16 
 
 
 
 
 
 
 
 
 65 
 
 66 
 
 26 
 
 22 
 
 18 
 
 12 
 
 -1- 4 
 
 7 
 
 34 
 
 
 
 
 
 
 
 66 
 
 67 
 
 28 
 
 24 
 
 20 
 
 15 
 
 9 
 
 1 
 
 -16 
 
 
 
 
 
 
 
 67 
 
 68 
 
 30 
 
 26 
 
 23 
 
 18 
 
 12 
 
 + 4 
 
 7 
 
 37 
 
 
 
 
 
 
 68 
 
 69 
 
 32 
 
 28 
 
 25 
 
 20 
 
 15 
 
 8 
 
 
 
 17 
 
 
 
 
 
 
 69 
 
 70 
 
 33 
 
 30 
 
 27 
 
 23 
 
 19 
 
 12 
 
 + 5 
 
 7 
 
 39 
 
 
 
 
 
 70 
 
 71 
 
 35 
 
 32 
 
 29 
 
 25 
 
 21 
 
 16 
 
 9 
 
 
 
 17 
 
 
 
 
 
 71 
 
 72 
 
 37 
 
 33 
 
 31 
 
 27 
 
 - 23 
 
 18 
 
 13 
 
 + 5 
 
 6 
 
 39 
 
 
 
 
 72 
 
 73 
 
 38 
 
 35 
 
 32 
 
 29 
 
 25 
 
 21 
 
 16 
 
 10 
 
 
 
 16 
 
 
 
 
 73 
 
 74 
 
 40 
 
 37 
 
 34 
 
 31 
 
 28 
 
 24 
 
 19 
 
 13 
 
 + 6 
 
 6 
 
 37 
 
 
 
 74 
 
 75 
 
 42 
 
 39 
 
 36 
 
 32 
 
 30 
 
 26 
 
 22 
 
 16 
 
 10 
 
 
 
 16 
 
 
 
 75 
 
 76 
 
 43 
 
 41 
 
 38 
 
 34 
 
 32 
 
 28 
 
 24 
 
 20 
 
 14 
 
 + 6 
 
 G 
 
 34 
 
 
 76 
 
 77 
 
 45 
 
 42 
 
 40 
 
 36 
 
 33 
 
 30 
 
 26 
 
 22 
 
 17 
 
 11 
 
 + 1 
 
 14 
 
 
 77 
 
 78 
 
 47 
 
 44 
 
 41 
 
 38 
 
 35 
 
 32 
 
 28 
 
 24 
 
 20 
 
 14 
 
 7 
 
 4 
 
 30 
 
 78 
 
 79 
 
 48 
 
 46 
 
 43 
 
 40 
 
 37 
 
 34 
 
 31 
 
 27 
 
 23 
 
 18 
 
 11 
 
 + 2 
 
 13 
 
 79 
 
 80 
 
 50 
 
 47 
 
 45 
 
 42 
 
 39 
 
 36 
 
 32 
 
 29 
 
 25 
 
 21 
 
 15 
 
 8 
 
 3 
 
 80 
 
 t. 
 
 18.0 
 
 19.0 
 
 20.0 
 
 21. 
 
 22.0 
 
 23 
 
 24.0 
 
 25.0 
 
 26. 
 
 27. 
 
 28.0 
 
 29.0 
 
 30. 
 
 t. 
 
77 
 
 TABLE I. Temperature of the deiv point, in degrees Fahrenheit. 
 
 J 
 
 Difference between the dry and wet thermometers (tr-t f ). 
 
 I 
 
 b 
 
 a 
 
 1.0 
 
 2.0 
 
 3.0 
 
 4.0 
 
 5.0 
 
 6.0 
 
 7.0 
 
 8.0 
 
 9.0 
 
 10. 
 
 11.0 
 
 12.0 
 
 1 
 
 80 
 
 79 
 
 77 
 
 76 
 
 74 
 
 73 
 
 72 
 
 70 
 
 68 
 
 67 
 
 65 
 
 63 
 
 62 
 
 80 
 
 81 
 
 80 
 
 78 
 
 77 
 
 75 
 
 74 
 
 73 
 
 71 
 
 70 
 
 68 
 
 66 
 
 6.5 
 
 63 
 
 81 
 
 82 
 
 81 
 
 79 
 
 78 
 
 77 
 
 75 
 
 74 
 
 72 
 
 71 
 
 69 
 
 68 
 
 66 
 
 64 
 
 82 
 
 83 
 
 82 
 
 80 
 
 79 
 
 78 
 
 76 
 
 75 
 
 73 
 
 72 
 
 70 
 
 69 
 
 67 
 
 65 
 
 83 
 
 84 
 
 83 
 
 81 
 
 80 
 
 79 
 
 77 
 
 76 
 
 74 
 
 73 
 
 71 
 
 70 
 
 68 
 
 67 
 
 84 
 
 85 
 
 84 
 
 82 
 
 81 
 
 80 
 
 78 
 
 77 
 
 75 
 
 74 
 
 72 
 
 71 
 
 69 
 
 68 
 
 85 
 
 86 
 
 85 
 
 83 
 
 82 
 
 81 
 
 79 
 
 78 
 
 76 
 
 75 
 
 73 
 
 72 
 
 71 
 
 69 
 
 86 
 
 87 
 
 86 
 
 84 
 
 83 
 
 82 
 
 80 
 
 79 
 
 78 
 
 76 
 
 74 
 
 73 
 
 72 
 
 70 
 
 87 
 
 88 
 
 87 
 
 85 
 
 84 
 
 83 
 
 81 
 
 80 
 
 79 
 
 77 
 
 75 
 
 74 
 
 73 
 
 71 
 
 88 
 
 89 
 
 88 
 
 86 
 
 85 
 
 84 
 
 82 
 
 81 
 
 80 
 
 78 
 
 76 
 
 76 
 
 74 
 
 72 
 
 89 
 
 90 
 
 89 
 
 87 
 
 86 
 
 85 
 
 84 
 
 82 
 
 81 
 
 79 
 
 78 
 
 77 
 
 75 
 
 74 
 
 90 
 
 91 
 
 90 
 
 88 
 
 87 
 
 86 
 
 85 
 
 83 
 
 82 
 
 80 
 
 79 
 
 78 
 
 76 
 
 75 
 
 91 
 
 92 
 
 91 
 
 89 
 
 88 
 
 87 
 
 86 
 
 84 
 
 83 
 
 82 
 
 80 
 
 79 
 
 77 
 
 76 
 
 92 
 
 93 
 
 92 
 
 91 
 
 89 
 
 88 
 
 87 
 
 85 
 
 84 
 
 83 
 
 81 
 
 80 
 
 78 
 
 77 
 
 93 
 
 94 
 
 93 
 
 92 
 
 90 
 
 89 
 
 88 
 
 86 
 
 85 
 
 84 
 
 82 
 
 81 
 
 80 
 
 78 
 
 94 
 
 95 
 
 94 
 
 93 
 
 91 
 
 90 
 
 89 
 
 87 
 
 86 
 
 85 
 
 83 
 
 82 
 
 81 
 
 79 
 
 95 
 
 96 
 
 95 
 
 94 
 
 92 
 
 91 
 
 90 
 
 88 
 
 87 
 
 86 
 
 84 
 
 83 
 
 82 
 
 80 
 
 96 
 
 97 
 
 96 
 
 95 
 
 93 
 
 92 
 
 91 
 
 90 
 
 88 
 
 87 
 
 86 
 
 84 
 
 83 
 
 81 
 
 97 
 
 98 
 
 97 
 
 96 
 
 94 
 
 93 
 
 92 
 
 91 
 
 89 
 
 88 
 
 87 
 
 85 
 
 84 
 
 83 
 
 98 
 
 99 
 
 98 
 
 97 
 
 95 
 
 94 
 
 93 
 
 92 
 
 90 
 
 89 
 
 88 
 
 86 
 
 85 
 
 84 
 
 99 
 
 100 
 
 99 
 
 98 
 
 96 
 
 95 
 
 94 
 
 93 
 
 91 
 
 90 
 
 89 
 
 87 
 
 86 
 
 85 
 
 100 
 
 101 
 
 100 
 
 99 
 
 97 
 
 96 
 
 95 
 
 94 
 
 92 
 
 91 
 
 90 
 
 88 
 
 87 
 
 86 
 
 101 
 
 102 
 
 101 
 
 100 
 
 98 
 
 97 
 
 96 
 
 95 
 
 93 
 
 92 
 
 91 
 
 90 
 
 88 
 
 87 
 
 102 
 
 103 
 
 102 
 
 101 
 
 99 
 
 98 
 
 97 
 
 96 
 
 94 
 
 93 
 
 92 
 
 91 
 
 89 
 
 88 
 
 103 
 
 104 
 
 103 
 
 102 
 
 100 
 
 99 
 
 98 
 
 97 
 
 96 
 
 94 
 
 93 
 
 92 
 
 90 
 
 89 
 
 104 
 
 105 
 
 104 
 
 103 
 
 101 
 
 100 
 
 99 
 
 98 
 
 97 
 
 95 
 
 94 
 
 93 
 
 91 
 
 90 
 
 105 
 
 106 
 
 105 
 
 104 
 
 102 
 
 101 
 
 100 
 
 99 
 
 98 
 
 96 
 
 95 
 
 94 
 
 93 
 
 91 
 
 106 
 
 107 
 
 106 
 
 105 
 
 103 
 
 102 
 
 101 
 
 100 
 
 99 
 
 97 
 
 96 
 
 95 
 
 94 
 
 92 
 
 107 
 
 108 
 
 107 
 
 106 
 
 104 
 
 103 
 
 102 
 
 101 
 
 100 
 
 98 
 
 97 
 
 96 
 
 95 
 
 93 
 
 108 
 
 109 
 
 108 
 
 107 
 
 105 
 
 104 
 
 103 
 
 102 
 
 101 
 
 99 
 
 98 
 
 97 
 
 96 
 
 94 
 
 109 
 
 110 
 
 109 
 
 108 
 
 107 
 
 105 
 
 104 
 
 .103 
 
 102 
 
 101 
 
 99 
 
 98 
 
 97 
 
 96 
 
 110 
 
 111 
 
 110 
 
 109 
 
 108 
 
 106 
 
 105 
 
 104 
 
 103 
 
 102 
 
 100 
 
 99 
 
 98 
 
 97 
 
 111 
 
 112 
 
 111 
 
 110 109 
 
 107 
 
 106 
 
 105 
 
 104 
 
 103 
 
 101 
 
 100 
 
 99 
 
 98 
 
 112 
 
 113 
 
 112 
 
 111 
 
 110 
 
 108 
 
 107 
 
 106 
 
 105 
 
 104 
 
 102 
 
 101 
 
 100 
 
 99 
 
 113 
 
 114 
 
 113 
 
 112 
 
 111 
 
 109 
 
 108 
 
 107 
 
 106 
 
 105 
 
 103 
 
 102 
 
 101 
 
 100 
 
 114 
 
 115 
 
 114 
 
 113 
 
 112 
 
 110 
 
 109 
 
 108 
 
 107 
 
 106 
 
 105 
 
 103 
 
 102 
 
 101 
 
 115 
 
 116 
 
 115 
 
 114 
 
 113 
 
 111 
 
 110 
 
 109 
 
 108 
 
 107 
 
 106 
 
 104 
 
 103 
 
 102 
 
 116 
 
 117 
 
 116 
 
 115 
 
 114 
 
 112 
 
 111 
 
 110 
 
 109 
 
 108 
 
 107 
 
 105 
 
 104 
 
 103 
 
 117 
 
 118 
 
 117 
 
 116 
 
 115 
 
 113 
 
 112 
 
 111 
 
 110 
 
 109 
 
 108 
 
 106 
 
 105 
 
 104 
 
 118 
 
 119 
 
 118 
 
 117 
 
 116 
 
 114 
 
 113 
 
 112 
 
 111 
 
 110 
 
 109 
 
 107 
 
 106 
 
 105 
 
 119 
 
 120 
 
 119 
 
 118 
 
 117 
 
 115 
 
 114 
 
 113 
 
 112 
 
 111 
 
 110 
 
 108 
 
 107 
 
 106 
 
 120 
 
 121 
 
 120 119 
 
 118 
 
 117 
 
 115 
 
 114 
 
 113 
 
 112 
 
 111 
 
 110 
 
 108 
 
 107 
 
 121 
 
 122 
 
 121 
 
 120 
 
 119 
 
 118 
 
 116 
 
 115 
 
 114 
 
 113 
 
 112 
 
 111 
 
 109 
 
 108 
 
 122 
 
 123 
 
 122 
 
 121 
 
 120 
 
 119 
 
 117 
 
 116 
 
 115 
 
 114 
 
 113 
 
 112 
 
 110 
 
 109 
 
 123 
 
 124 
 
 123 
 
 122 
 
 121 
 
 120 
 
 118 
 
 117 
 
 116 
 
 115 
 
 114 
 
 113 
 
 111 
 
 110 
 
 124 
 
 125 
 
 124 
 
 123 
 
 122 
 
 121 
 
 119 
 
 118 
 
 117 
 
 116 
 
 115 
 
 114 
 
 112 
 
 111 
 
 1-25 
 
 126 
 
 125 
 
 124 
 
 123 
 
 122 
 
 120 
 
 119 
 
 118 
 
 117 
 
 116 
 
 115 
 
 114 
 
 112 
 
 126 
 
 127 
 
 r/6 
 
 125 
 
 124 
 
 123 
 
 121 
 
 120 
 
 119 
 
 118 
 
 117 
 
 116 
 
 115 
 
 113 
 
 127 
 
 128 
 
 127 
 
 126 
 
 125 
 
 124 
 
 122 
 
 121 
 
 120 
 
 119 
 
 118 
 
 117 
 
 116 
 
 114 
 
 128 
 
 129 
 
 128 
 
 127 
 
 126 
 
 125 
 
 123 
 
 122 
 
 121 
 
 120 
 
 119 
 
 118 
 
 117 
 
 115 
 
 129 
 
 130 
 
 129 
 
 128 
 
 127 
 
 126 
 
 124 
 
 123 
 
 122 
 
 121 
 
 120 
 
 119 
 
 118 
 
 117 
 
 130 
 
 131 
 
 130 
 
 129 
 
 128 
 
 127 
 
 125 
 
 124 
 
 123 
 
 122 
 
 121 
 
 120 
 
 119 
 
 118 
 
 131 
 
 132 
 
 131 
 
 130 
 
 129 
 
 128 
 
 126 
 
 125 
 
 124 
 
 123 
 
 122 
 
 121 
 
 120 
 
 119 
 
 132 
 
 133 
 
 132 
 
 131 
 
 130 
 
 129 
 
 128 
 
 126 ' 125 124 
 
 123 
 
 122 
 
 121 
 
 120 
 
 133 
 
 134 
 
 133 
 
 132 
 
 131 
 
 130 
 
 129 
 
 127 
 
 126 
 
 125 
 
 124 
 
 123 
 
 122 
 
 121 
 
 134 
 
 135 
 
 134 
 
 133 
 
 132 
 
 131 
 
 130 
 
 128 
 
 127 
 
 126 
 
 125 
 
 124 
 
 123 
 
 122 
 
 135 
 
 136 
 
 135 
 
 134 
 
 133 
 
 132 
 
 131 
 
 129 
 
 128 
 
 127 
 
 126 
 
 125 
 
 124 
 
 123 
 
 136 
 
 137 
 
 136 
 
 135 
 
 134 
 
 133 
 
 132 
 
 130 
 
 129 
 
 128 
 
 127 
 
 126 
 
 125 
 
 124 
 
 137 
 
 138 
 
 137 
 
 136 
 
 135 
 
 134 
 
 133 
 
 131 
 
 J30 
 
 129 
 
 128 
 
 127 
 
 126 
 
 125 
 
 138 
 
 139 
 
 138 
 
 137 
 
 136 
 
 135 
 
 134 
 
 132 
 
 131 
 
 130 
 
 129 
 
 128 
 
 127 
 
 126 
 
 139 
 
 140 
 
 139 
 
 138 
 
 137 
 
 136 
 
 135 
 
 133 
 
 132 
 
 131 
 
 130 
 
 129 
 
 128 
 
 127 
 
 140 
 
 t. 
 
 1.0 
 
 2.0 
 
 3.0 
 
 4.0 
 
 5.0 
 
 6.0 
 
 7.0 
 
 8.0 
 
 9.0 
 
 10.0 
 
 11. 
 
 12.0 
 
 I. 
 
78 
 
 TABLE I. Temperature of the dew point, in degrees Fahrenheit. 
 
 t . 
 
 (Dryther.) 
 
 Difference between the dry and wet thermometers (< t'). 
 
 ? 
 
 ~ 
 
 I 
 
 12.0 
 
 13.0 
 
 14.0 
 
 15.0 
 
 16. 
 
 17.0 
 
 18.0 
 
 19.0 
 
 20.0 
 
 21.0 
 
 22.0 
 
 23.0 
 
 24.0 
 
 80 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 47 
 
 45 
 
 42 
 
 39 
 
 36 
 
 32 
 
 80 
 
 81 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 44 
 
 41 
 
 38 
 
 35 
 
 81 
 
 82 
 
 64 
 
 62 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 50 
 
 48 
 
 45 
 
 43 
 
 40 
 
 37 
 
 82 
 
 83 
 
 65 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 47 
 
 44 
 
 42 
 
 39 
 
 83 
 
 84 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 46 
 
 43 
 
 41 
 
 84 
 
 85 
 
 68 
 
 66 
 
 64 
 
 62 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 50 
 
 48 
 
 45 
 
 42 
 
 85 
 
 86 
 
 69 
 
 67 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 49 
 
 47 
 
 44 
 
 86 
 
 87 
 
 70 
 
 68 
 
 67 
 
 65 
 
 63 
 
 6 o 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 48 
 
 46 
 
 87 
 
 88 
 
 71 
 
 70 
 
 68 
 
 66 
 
 64 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 50 
 
 48 
 
 88 
 
 89 
 
 72 
 
 71 
 
 69 
 
 67 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 49 
 
 89 
 
 90 
 
 74 
 
 72 
 
 70 
 
 69 
 
 67 
 
 65 
 
 63 
 
 62 
 
 60 
 
 58 
 
 56 
 
 53 
 
 51 
 
 90 
 
 91 
 
 75 
 
 73 
 
 72 
 
 70 
 
 68 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 91 
 
 92 
 
 76 
 
 74 
 
 73 
 
 71 
 
 69 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 92 
 
 93 
 
 77 
 
 75 
 
 74 
 
 72 
 
 71 
 
 69 
 
 67 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 66 
 
 93 
 
 94 
 
 78 
 
 77 
 
 75 
 
 73 
 
 72 
 
 70 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 94 
 
 95 
 
 79 
 
 78 
 
 76 
 
 75 
 
 73 
 
 71 
 
 70 
 
 68 
 
 66 
 
 64 
 
 63 
 
 61 
 
 59 
 
 95 
 
 96 
 
 80 
 
 79 
 
 77 
 
 76 
 
 74 
 
 73 
 
 71 
 
 69 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 96 
 
 97 
 
 81 
 
 80 
 
 78 
 
 77 
 
 75 
 
 74 
 
 72 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 97 
 
 98 
 
 83 
 
 81 
 
 80 
 
 78 
 
 77 
 
 75 
 
 73 
 
 72 
 
 70 
 
 68 
 
 67 
 
 65 
 
 63 
 
 98 
 
 99 
 
 84 
 
 82 
 
 81 
 
 79 
 
 78 
 
 76 
 
 75 
 
 73 
 
 71 
 
 70 
 
 68 
 
 66 
 
 64 
 
 99 
 
 100 
 
 85 
 
 83 
 
 82 
 
 80 
 
 79 
 
 77 
 
 76 
 
 74 
 
 73 
 
 71 
 
 69 
 
 67 
 
 66 
 
 100 
 
 101 
 
 86 
 
 84 
 
 83 
 
 82 
 
 80 
 
 79 
 
 77 
 
 75 
 
 74 
 
 72 
 
 71 
 
 69 
 
 67 
 
 101 
 
 102 
 
 87 
 
 85 
 
 84 
 
 83 
 
 81 
 
 80 
 
 78 
 
 77 
 
 75 
 
 73 
 
 72 
 
 70 
 
 68 
 
 102 
 
 103 
 
 88 
 
 87 
 
 85 
 
 84 
 
 82 
 
 81 
 
 79 
 
 78 
 
 76 
 
 75 
 
 73 
 
 71 
 
 70 
 
 103 
 
 104 
 
 89 
 
 88 
 
 86 
 
 85 
 
 83 
 
 82 
 
 81 
 
 79 
 
 78 
 
 76 
 
 74 
 
 73 
 
 71 
 
 104 
 
 105 
 
 90 
 
 89 
 
 87 
 
 86 
 
 85 
 
 83 
 
 82 
 
 80 
 
 79 
 
 77 
 
 76 
 
 74 
 
 72 
 
 105 
 
 106 
 
 91 
 
 90 
 
 89 
 
 87 
 
 86 
 
 84 
 
 83 
 
 81 
 
 80 
 
 78 
 
 77 
 
 75 
 
 74 
 
 106 
 
 107 
 
 92 
 
 91 
 
 90 
 
 88 
 
 87 
 
 85 
 
 84 
 
 83 
 
 81 
 
 80 
 
 78 
 
 76 
 
 75 
 
 107 
 
 108 
 
 93 
 
 92 
 
 91 
 
 89 
 
 88 
 
 87 
 
 85 
 
 84 
 
 82 
 
 81 
 
 79 
 
 78 
 
 76 
 
 108 
 
 109 
 
 94 
 
 93 
 
 92 
 
 90 
 
 89 
 
 88 
 
 86 
 
 85 
 
 83 
 
 2 
 
 80 
 
 79 
 
 77 
 
 109 
 
 110 
 
 96 
 
 94 
 
 93 
 
 92 
 
 90 
 
 89 
 
 87 
 
 86 
 
 85 
 
 83 
 
 82 
 
 80 
 
 79 
 
 110 
 
 111 
 
 97 
 
 95 
 
 94 
 
 93 
 
 91 
 
 90 
 
 89 
 
 87 
 
 86 
 
 84 
 
 83 
 
 81 
 
 80 
 
 111 
 
 112 
 
 98 
 
 96 
 
 95 
 
 94 
 
 92 
 
 91 
 
 90 
 
 88 
 
 87 
 
 85 
 
 84 
 
 83 
 
 81 
 
 112 
 
 113 
 
 99 
 
 97 
 
 96 
 
 95 
 
 93 
 
 92 
 
 91 
 
 89 
 
 88 
 
 87 
 
 85 
 
 84 
 
 82 
 
 113 
 
 114 
 
 100 
 
 99 
 
 97 
 
 96 
 
 95 
 
 93 
 
 92 
 
 91 
 
 89 
 
 88 
 
 86 
 
 85 
 
 83 
 
 114 
 
 115 
 
 101 
 
 100 
 
 98 
 
 97 
 
 96 
 
 94 
 
 93 
 
 92 
 
 90 
 
 89 
 
 88 
 
 86 
 
 85 
 
 115 
 
 116 
 
 102 
 
 101 
 
 99 
 
 98 
 
 97 
 
 95 
 
 94 
 
 93 
 
 91 
 
 90 
 
 89 
 
 87 
 
 86 
 
 116 
 
 117 
 
 103 
 
 102 
 
 100 
 
 99 
 
 98 
 
 96 
 
 95 
 
 94 
 
 93 
 
 91 
 
 90 
 
 88 
 
 87 
 
 117 
 
 118 
 
 104 
 
 103 
 
 101 
 
 100 
 
 99 
 
 97 
 
 96 
 
 95 
 
 94 
 
 92 
 
 91 
 
 90 
 
 88 
 
 118 
 
 119 
 
 105 
 
 104 
 
 103 
 
 101 
 
 100 
 
 99 
 
 97 
 
 96 
 
 95 
 
 93 
 
 92 
 
 91 
 
 89 
 
 119 
 
 120 
 
 106 
 
 105 
 
 104 
 
 102 
 
 101 
 
 100 
 
 99 
 
 97 
 
 96 
 
 95 
 
 93 
 
 92 
 
 90 
 
 120 
 
 121 
 
 107 
 
 106 
 
 105 
 
 103 
 
 102 
 
 101 
 
 100 
 
 98 
 
 97 
 
 96 
 
 94 
 
 93 
 
 92 
 
 121 
 
 122 
 
 108 
 
 107 
 
 106 
 
 105 
 
 103 
 
 102 
 
 101 
 
 99 
 
 98 
 
 97 
 
 96 
 
 94 
 
 93 
 
 122 
 
 123 
 
 109 
 
 108 
 
 107 
 
 106 
 
 104 
 
 103 
 
 102 
 
 101 
 
 99 
 
 98 
 
 97 
 
 95 
 
 94 
 
 123 
 
 124 
 
 110 
 
 109 
 
 108 
 
 107 
 
 105 
 
 104 
 
 103 
 
 102 
 
 100 
 
 99 
 
 98 
 
 96 
 
 95 
 
 124 
 
 125 
 
 111 
 
 110 
 
 109 
 
 108 
 
 106 
 
 105 
 
 104 
 
 103 
 
 101 
 
 100 
 
 99 
 
 98 
 
 96 
 
 125 
 
 126 
 
 112 
 
 111 
 
 110 
 
 109 
 
 108 
 
 106 
 
 105 
 
 104 
 
 103 
 
 101 
 
 100 
 
 99 
 
 97 
 
 126 
 
 127 
 
 113 
 
 112 
 
 111 
 
 110 
 
 109 
 
 107 
 
 106 
 
 105 
 
 104 
 
 102 
 
 101 
 
 100 
 
 98 
 
 127 
 
 128 
 
 114 
 
 113 
 
 112 
 
 111 
 
 110 
 
 108 
 
 107 
 
 106 
 
 105 
 
 103 
 
 102 
 
 101 
 
 100 
 
 128 
 
 129 
 
 115 
 
 114 
 
 113 
 
 112 
 
 111 
 
 110 
 
 108 
 
 107 
 
 106 
 
 105 
 
 103 
 
 102 
 
 101 
 
 129 
 
 130 
 
 117 
 
 115 
 
 114 
 
 113 
 
 112 
 
 111 
 
 109 
 
 108 
 
 107 
 
 106 
 
 104 
 
 103 
 
 102 
 
 130 
 
 131 
 
 118 
 
 116 
 
 115 
 
 114 
 
 113 
 
 112 
 
 110 
 
 109 
 
 108 
 
 107 
 
 106 
 
 104 
 
 103 
 
 131 
 
 132 
 
 119 
 
 117 
 
 116 
 
 115 
 
 114 
 
 113 
 
 112 
 
 110 
 
 109 
 
 108 
 
 107 
 
 105 
 
 104 
 
 132 
 
 133 
 
 120 
 
 118 
 
 117 
 
 116 
 
 115 
 
 114 
 
 113 
 
 111 
 
 110 
 
 109 
 
 108 
 
 106 
 
 105 
 
 133 
 
 134 
 
 121 
 
 120 
 
 118 
 
 117 
 
 116 
 
 115 
 
 114 
 
 112 
 
 111 
 
 110 
 
 109 
 
 108 
 
 106 
 
 134 
 
 135 
 
 122 
 
 121 
 
 119 
 
 118 
 
 117 
 
 116 
 
 115 
 
 113 
 
 112 
 
 111 
 
 110 
 
 109 
 
 107 
 
 135 
 
 136 
 
 123 
 
 122 
 
 120 
 
 119 
 
 118 
 
 117 
 
 116 
 
 115 
 
 113 
 
 112 
 
 111 
 
 110 
 
 108 
 
 136 
 
 137 
 
 124 
 
 123 
 
 121 
 
 120 
 
 119 
 
 118 
 
 117 
 
 116 
 
 114 
 
 113 
 
 112 
 
 111 
 
 110 
 
 137 
 
 138 
 
 125 
 
 124 
 
 122 
 
 121 
 
 120 
 
 119 
 
 118 
 
 117 
 
 115 
 
 114 
 
 113 
 
 112 
 
 111 
 
 138 
 
 139 
 
 126 
 
 125 
 
 124 
 
 122 
 
 121 
 
 120 
 
 119 
 
 118 
 
 117 
 
 115 
 
 114 
 
 113 
 
 112 
 
 139 
 
 140 
 
 127 
 
 126 
 
 125 
 
 123 
 
 122 
 
 121 
 
 120 
 
 119 
 
 118 
 
 116 
 
 115 
 
 114 
 
 113 
 
 140 
 
 t. 
 
 12. 
 
 13.0 
 
 14.0 
 
 15. 
 
 16.0 
 
 17.0 
 
 18.0 
 
 19.0 
 
 20.0 
 
 21.0 
 
 22.0 
 
 23.0 
 
 24.0 
 
 i 
 
79 
 
 TABLE I. Temperature of the dew point, in degrees Fahrenheit. 
 
 I 
 
 Difference between the dry and wet thermometers ( t <'). 
 
 I 
 
 1 
 
 24. 
 
 25.0 
 
 26.0 
 
 27. 
 
 28.0 
 
 29.0 
 
 30.0 
 
 31.0 
 
 32. 
 
 33.0 
 
 34.0 
 
 35.0 
 
 36. 
 
 "I 
 
 80 
 
 32 
 
 29 
 
 25 
 
 21 
 
 15 
 
 8 
 
 3 
 
 27 
 
 
 
 
 
 
 80 
 
 81 
 
 35 
 
 31 
 
 28 
 
 24 
 
 18 
 
 12 
 
 +3 
 
 11 
 
 
 
 
 
 
 81 
 
 82 
 
 37 
 
 33 
 
 30 
 
 26 
 
 ' 22 
 
 16 
 
 9 
 
 2 
 
 -24 
 
 
 
 
 
 82 
 
 83 
 
 39 
 
 35 
 
 32 
 
 28 
 
 24 
 
 19 
 
 13 
 
 + 5 
 
 9 
 
 
 
 
 
 83 
 
 84 
 
 41 
 
 37 
 
 34 
 
 30 
 
 27 
 
 22 
 
 17 
 
 10 
 
 
 
 -20 
 
 
 
 
 84 
 
 85 
 
 42 
 
 39 
 
 36 
 
 32 
 
 29 
 
 25 
 
 20 
 
 14 
 
 + 6 
 
 - 7 
 
 64 
 
 
 
 85 
 
 86 
 
 44 
 
 41 
 
 38 
 
 35 
 
 31 
 
 28 
 
 23 
 
 18 
 
 11 
 
 + 1 
 
 17 
 
 
 
 86 
 
 87 
 
 46 
 
 43 
 
 40 
 
 37 
 
 33 
 
 30 
 
 26 
 
 21 
 
 15 
 
 7 
 
 5 
 
 38 
 
 
 87 
 
 88 
 
 48 
 
 45 
 
 42 
 
 39 
 
 35 
 
 32 
 
 28 
 
 24 
 
 19 
 
 12 
 
 + 3 
 
 13 
 
 
 88 
 
 89 
 
 49 
 
 47 
 
 44 
 
 41 
 
 38 
 
 34 
 
 31 
 
 27 
 
 22 
 
 16 
 
 9 
 
 2 
 
 28 
 
 89 
 
 90 
 
 51 
 
 48 
 
 46 
 
 43 
 
 40 
 
 36 
 
 32 
 
 29 
 
 25 
 
 20 
 
 13 
 
 + * 
 
 10 
 
 90 
 
 91 
 
 53 
 
 50 
 
 47 
 
 45 
 
 42 
 
 38 
 
 35 
 
 32 
 
 28 
 
 23 
 
 18 
 
 10 
 
 
 
 91 
 
 92 
 
 54 
 
 52 
 
 49 
 
 46 
 
 44 
 
 41 
 
 37 
 
 34 
 
 30 
 
 26 
 
 21 
 
 15 
 
 + 7 
 
 92 
 
 93 
 
 56 
 
 63 
 
 51 
 
 48 
 
 46 
 
 43 
 
 39 
 
 36 
 
 32 
 
 29 
 
 24 
 
 19 
 
 12 
 
 93 
 
 94 
 
 57 
 
 55 
 
 53 
 
 50 
 
 47 
 
 45 
 
 42 
 
 38 
 
 35 
 
 31 
 
 27 
 
 22 
 
 16 
 
 94 
 
 95 
 
 59 
 
 56 
 
 54 
 
 52 
 
 49 
 
 46 
 
 44 
 
 40 
 
 37 
 
 33 
 
 30 
 
 25 
 
 20 
 
 95 
 
 96 
 
 60 
 
 58 
 
 56 
 
 53 
 
 51 
 
 48 
 
 46 
 
 43 
 
 39 
 
 36 
 
 32 
 
 28 
 
 24 
 
 96 
 
 97 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 60 
 
 47 
 
 45 
 
 41 
 
 38 
 
 34 
 
 31 
 
 26 
 
 97 
 
 98 
 
 63 
 
 61 
 
 59 
 
 57 
 
 54 
 
 52 
 
 49 
 
 47 
 
 44 
 
 40 
 
 37 
 
 33 
 
 29 
 
 98 
 
 99 
 
 64 
 
 02 
 
 60 
 
 58 
 
 56 
 
 54 
 
 51 
 
 48 
 
 46 
 
 43 
 
 39 
 
 35 
 
 32 
 
 99 
 
 100 
 
 66 
 
 64 
 
 62 
 
 60 
 
 57 
 
 55 
 
 53 
 
 50 
 
 48 
 
 46 
 
 41 
 
 38 
 
 34 
 
 100 
 
 101 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 54 
 
 52 
 
 49 
 
 4V 
 
 44 
 
 40 
 
 37 
 
 101 
 
 102 
 
 68 
 
 66 
 
 65 
 
 63 
 
 61 
 
 58 
 
 56 
 
 54 
 
 51 
 
 49 
 
 46 
 
 43 
 
 39 
 
 102 
 
 103 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 55 
 
 53 
 
 50 
 
 48 
 
 45 
 
 41 
 
 103 
 
 104 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 52 
 
 50 
 
 47 
 
 44 
 
 104 
 
 105 
 
 72 
 
 "(0 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 56 
 
 54 
 
 52 
 
 49 
 
 ' 46 
 
 105 
 
 106 
 
 74 
 
 V2 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 53 
 
 51 
 
 48 
 
 106 
 
 107 
 
 75 
 
 73 
 
 71 
 
 VO 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 57 
 
 55 
 
 52 
 
 50 
 
 107 
 
 108 
 
 76 
 
 74 
 
 73 
 
 Yl 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 54 
 
 52 
 
 108 
 
 109 
 
 77 
 
 76 
 
 74 
 
 72 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 58 
 
 56 
 
 54 
 
 109 
 
 110 
 
 79 
 
 77 
 
 75 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 55 
 
 110 
 
 II 1 
 
 80 
 
 73 
 
 77 
 
 75 
 
 73 
 
 71 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 59 
 
 57 
 
 111 
 
 112 
 
 81 
 
 79 
 
 78 
 
 76 
 
 74 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 112 
 
 113 
 
 82 
 
 81 
 
 79 
 
 77 
 
 76 
 
 74 
 
 72 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 60 
 
 113 
 
 114 
 
 83 
 
 82 
 
 80 
 
 79 
 
 77 
 
 75 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 114 
 
 115 
 
 85 
 
 83 
 
 82 
 
 80 
 
 78 
 
 77 
 
 75 
 
 73 
 
 72 
 
 70 
 
 68 
 
 66. 
 
 64 
 
 115 
 
 116 
 
 86 
 
 84 
 
 83 
 
 81 
 
 80 
 
 78 
 
 76 
 
 75 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 116 
 
 117 
 
 87 
 
 86 
 
 84 
 
 82 
 
 81 
 
 79 
 
 78 
 
 76 
 
 74 
 
 72 
 
 71 
 
 69 
 
 67 
 
 117 
 
 118 
 
 88 
 
 87 
 
 85 
 
 84 
 
 82 
 
 81 
 
 79 
 
 77 
 
 76 
 
 74 
 
 72 
 
 70 
 
 68 
 
 118 
 
 119 
 
 89 
 
 88 
 
 86 
 
 85 
 
 83 
 
 82 
 
 80 
 
 79 
 
 77 
 
 75 
 
 74 
 
 72 
 
 70 
 
 119 
 
 120 
 
 90 
 
 89 
 
 88 
 
 86 
 
 85 
 
 83 
 
 82 
 
 80 
 
 78 
 
 77 
 
 75 
 
 73 
 
 71 
 
 120 
 
 121 
 
 92 
 
 90 
 
 89 
 
 87 
 
 86 
 
 84 
 
 83 
 
 81 
 
 80 
 
 78 
 
 76 
 
 74 
 
 73 
 
 121 
 
 122 
 
 93 
 
 91 
 
 90 
 
 89 
 
 87 
 
 86 
 
 84 
 
 83 
 
 81 
 
 79 
 
 78 
 
 76 
 
 74 
 
 122 
 
 123 
 
 94 
 
 93 
 
 91 
 
 90 
 
 88 
 
 87 
 
 85 
 
 84 
 
 82 
 
 81 
 
 79 
 
 77 
 
 75 
 
 123 
 
 124 
 
 96 
 
 94 
 
 92 
 
 91 
 
 89 
 
 88 
 
 87 
 
 85 
 
 83 
 
 82 
 
 80 
 
 79 
 
 77 
 
 124 
 
 125 
 
 96 
 
 95 
 
 93 
 
 92 
 
 91 
 
 89 
 
 88 
 
 86 
 
 85 
 
 83 
 
 82 
 
 80 
 
 78 
 
 125 
 
 126 
 
 97 
 
 96 
 
 95 
 
 93 
 
 92 
 
 90 
 
 89 
 
 87 
 
 86 
 
 84 
 
 83 
 
 81 
 
 80 
 
 126 
 
 127 
 
 98 
 
 97 
 
 96 
 
 94 
 
 93 
 
 92 
 
 90 
 
 89 
 
 87 
 
 86 
 
 84 
 
 83 
 
 81 
 
 127 
 
 128 
 
 100 
 
 98 
 
 97 
 
 96 
 
 94 
 
 93 
 
 91 
 
 90 
 
 88 
 
 87 
 
 85 
 
 84 
 
 82 
 
 128 
 
 129 
 
 101 
 
 99 
 
 98 
 
 97 
 
 95 
 
 94 
 
 93 
 
 91 
 
 90 
 
 88 
 
 87 
 
 85 
 
 84 
 
 129 
 
 130 
 131 
 132 
 133 
 134 
 
 102 
 
 103 
 104 
 105 
 106 
 
 101 
 102 
 103 
 104 
 105 
 
 99 
 100 
 101 
 103 
 104 
 
 98 
 99 
 100 
 101 
 102 
 
 97 
 98 
 99 
 100 
 101 
 
 95 
 96 
 97 
 99 
 100 
 
 94 
 95 
 96 
 97 
 98 
 
 92 
 94 
 95 
 96 
 
 97 
 
 91 
 92 
 93 
 94 
 96 
 
 89 
 91 
 92 
 93 
 94 
 
 88 
 89 
 90 
 92 
 93 
 
 86 
 88 
 89 
 90 
 91 
 
 85 
 86 
 87 
 89 
 90 
 
 130 
 131 
 132 
 133 
 134 
 
 135 
 136 
 137 
 138 
 139 
 
 107 
 108 
 110 
 111 
 112 
 
 106 
 107 
 108 
 109 
 110 
 
 105 
 106 
 107 
 108 
 109 
 
 104 
 105 
 106 
 107 
 108 
 
 102 
 103 
 104 
 106 
 107 
 
 101 
 102 
 103 
 104 
 105 
 
 100 
 101 
 102 
 103 
 104 
 
 98 
 99 
 101 
 102 
 103 
 
 97 
 98 
 99 
 100 
 101 
 
 95 
 97 
 98 
 99 
 100 
 
 94 
 95 
 96 
 
 98 
 99 
 
 93 
 94 
 95 
 96 
 97 
 
 91 
 92 
 94 
 95 
 96 
 
 135 
 136 
 137 
 138 
 139 
 
 140 
 
 113 
 
 112 
 
 110 
 
 109 
 
 108 
 
 107 
 
 105 
 
 104 
 
 103 
 
 101 
 
 100 
 
 99 
 
 97 
 
 140 
 
 t. 
 
 24. 
 
 25 .0 
 
 26. 
 
 27.0 
 
 28.0 
 
 29.0 
 
 30.0 
 
 31.0 
 
 32.0 
 
 33. 
 
 34.0 
 
 35.0 
 
 36.0 
 
 t. 
 
TABLE I. Temperature of the dew point, in degrees Fahrenheit. 
 
 1 
 
 Difference between the dry and wet thermometers, (<<'). - 
 
 ? 
 
 I 
 
 36.0 
 
 37 -.0 
 
 38.0 
 
 39.0 
 
 40.0 
 
 41. 
 
 42.0 
 
 43.0 
 
 44. 
 
 450 
 
 46. 
 
 47. 
 
 48.0 
 
 b 
 
 89 
 
 28 
 
 
 
 
 
 
 
 
 
 
 
 
 
 89 
 
 90 
 
 10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 90 
 
 91 
 
 
 
 -22 
 
 
 
 
 
 
 
 
 
 
 
 
 91 
 
 92 
 
 + 7 
 
 7 
 
 16 
 
 
 
 
 
 
 
 
 
 
 
 92 
 
 93 
 
 12 
 
 + 2 
 
 4 
 
 
 
 
 
 
 
 
 
 
 
 93 
 
 94 
 
 16 
 
 8 
 
 + 4 
 
 37 
 
 
 
 
 
 
 
 
 
 
 94 
 
 95 
 
 20 
 
 13 
 
 10 
 
 12 
 
 
 
 
 
 
 
 
 
 
 95 
 
 96 
 
 24 
 
 15 
 
 15 
 
 - 1 
 
 25 
 
 
 
 
 
 
 
 
 
 96 
 
 97 
 
 26 
 
 21 
 
 19 
 
 + 7 
 
 8 
 
 
 
 
 
 
 
 
 
 97 
 
 98 
 
 29 
 
 25 
 
 23 
 
 12 
 
 + 2 
 
 18 
 
 
 
 
 
 
 
 
 98 
 
 99 
 
 32 
 
 28 
 
 26 
 
 17 
 
 9 
 
 4 
 
 -42 
 
 
 
 
 
 
 
 99 
 
 100 
 
 34 
 
 30 
 
 29 
 
 21 
 
 14 
 
 + 5 
 
 12 
 
 
 
 
 
 
 
 100 
 
 101 
 
 37 
 
 32 
 
 32 
 
 24 
 
 18 
 
 11 
 
 
 
 25 
 
 
 
 
 
 
 101 
 
 102 
 
 39 
 
 35 
 
 34 
 
 27 
 
 22 
 
 16 
 
 + 7 
 
 7 
 
 
 
 
 
 
 102 
 
 103 
 
 41 
 
 38 
 
 34 
 
 30 
 
 26 
 
 20 
 
 13 
 
 + 3 
 
 16 
 
 
 
 
 
 103 
 
 104 
 
 44 
 
 40 
 
 37 
 
 32 
 
 29 
 
 24 
 
 18 
 
 10 
 
 2 
 
 -38 
 
 
 
 
 104 
 
 105 
 
 46 
 
 43 
 
 39 
 
 35 
 
 31 
 
 27 
 
 22 
 
 15 
 
 + 6 
 
 10 
 
 
 
 
 105 
 
 106 
 
 48 
 
 45 
 
 42 
 
 38 
 
 34 
 
 30 
 
 25 
 
 20 
 
 12 
 
 + 1 
 
 -22 
 
 
 
 106 
 
 107 
 
 50 
 
 47 
 
 44 
 
 40 
 
 37 
 
 32 
 
 28 
 
 24 
 
 17 
 
 9 
 
 5 
 
 
 
 107 
 
 108 ' 
 
 52 
 
 49 
 
 46 
 
 43 
 
 39 
 
 35 
 
 31 
 
 27 
 
 21 
 
 14 
 
 + 5 
 
 -13 
 
 
 108 
 
 109 
 
 54 
 
 51 
 
 48 
 
 43 
 
 42 
 
 38 
 
 34 
 
 30 
 
 25 
 
 - 19 
 
 12 
 
 
 
 28 
 
 109 
 
 110 
 
 55 
 
 53 
 
 50 
 
 47 
 
 44 
 
 41 
 
 37 
 
 33 
 
 28 
 
 23 
 
 17 
 
 + 8 
 
 7 
 
 110 
 
 111 
 
 57 
 
 54 
 
 52 
 
 49 
 
 46 
 
 43 
 
 39 
 
 35 
 
 31 
 
 27 
 
 21 
 
 14 
 
 + 4 
 
 111 
 
 112 
 
 59 
 
 56 
 
 54 
 
 51 
 
 48 
 
 45 
 
 42 
 
 38 
 
 34 
 
 30 
 
 25 
 
 19 
 
 11 
 
 112 
 
 113 
 
 60 
 
 58 
 
 56 
 
 53 
 
 50 
 
 47 
 
 44 
 
 41 
 
 37 
 
 32 
 
 28 
 
 23 
 
 16 
 
 113 
 
 114 
 
 62 
 
 60 
 
 58 
 
 55 
 
 52 
 
 50 
 
 47 
 
 43 
 
 40 
 
 35 
 
 31 
 
 27 
 
 21 
 
 114 
 
 115 
 
 64 
 
 62 
 
 59 
 
 57 
 
 54 
 
 52 
 
 49 
 
 46 
 
 42 
 
 38 
 
 34 
 
 30 
 
 25 
 
 115 
 
 116 
 
 65 
 
 63 
 
 61 
 
 59 
 
 56 
 
 54 
 
 51 
 
 43 
 
 45 
 
 41 
 
 37 
 
 33 
 
 28 
 
 116 
 
 117 
 
 67 
 
 65 
 
 63 
 
 60 
 
 58 
 
 56 
 
 53 
 
 50 
 
 47 
 
 44 
 
 40 
 
 36 
 
 32 
 
 117 
 
 118 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 57 
 
 55 
 
 52 
 
 49 
 
 46 
 
 43 
 
 39 
 
 31 
 
 118 
 
 119 
 
 70 
 
 68 
 
 66 
 
 64 
 
 61 
 
 59 
 
 57 
 
 54 
 
 51 
 
 48 
 
 45 
 
 42 
 
 37 
 
 119 
 
 120 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 56 
 
 53 
 
 50 
 
 47 
 
 44 
 
 40 
 
 120 
 
 121 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 60 
 
 58 
 
 55 
 
 52 
 
 50 
 
 47 
 
 43 
 
 121 
 
 122 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 57 
 
 54 
 
 52 
 
 49 
 
 46 
 
 122 
 
 123 
 
 75 
 
 74 
 
 7-2 
 
 70 
 
 68 
 
 66 
 
 64 
 
 61 
 
 59 
 
 56 
 
 54 
 
 51 
 
 48 
 
 123 
 
 124 
 
 77 
 
 75 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 58 
 
 56 
 
 53 
 
 50 
 
 124 
 
 125 
 
 78 
 
 76 
 
 75 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 60 
 
 58 
 
 55 
 
 52 
 
 125 
 
 126 
 
 80 
 
 78 
 
 76 
 
 74 
 
 73 
 
 71 
 
 69 
 
 67 
 
 64 
 
 62 
 
 60 
 
 57 
 
 54 
 
 126 
 
 127 
 
 81 
 
 79 
 
 78 
 
 76 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 59 
 
 56 
 
 127 
 
 128 
 
 82 
 
 81 
 
 79 
 
 77 
 
 75 
 
 74 
 
 72 
 
 70 
 
 68 
 
 65 
 
 63 
 
 61 
 
 58 
 
 128 
 
 129 
 
 84 
 
 82 
 
 80 
 
 79 
 
 77 
 
 75 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 60 
 
 129 
 
 130 
 
 85 
 
 83 
 
 82 
 
 80 
 
 78 
 
 76 
 
 75 
 
 73 
 
 71 
 
 69 
 
 67 
 
 64 
 
 62 
 
 130 
 
 131 
 
 86 
 
 85 
 
 83 
 
 81 
 
 80 
 
 78 
 
 76 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 131 
 
 132 
 
 87 
 
 86 
 
 84 
 
 83 
 
 81 
 
 79 
 
 78 
 
 76 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 132 
 
 133 
 
 89 
 
 87 
 
 86 
 
 84 
 
 82 
 
 81 
 
 79 
 
 77 
 
 75 
 
 73 
 
 71 
 
 69 
 
 67 
 
 133 
 
 134 
 
 90 
 
 88 
 
 87 
 
 85 
 
 84 
 
 82 
 
 80 
 
 79 
 
 77 
 
 75 
 
 73 
 
 71 
 
 69 
 
 134 
 
 135 
 
 91 
 
 90 
 
 88 
 
 87 
 
 85 
 
 83 
 
 82 
 
 
 
 78 
 
 76 
 
 75 
 
 73 
 
 71 
 
 135 
 
 136 
 
 92 
 
 91 
 
 89 
 
 88 
 
 86 
 
 85 
 
 83 
 
 81 
 
 80 
 
 78 
 
 76 
 
 74 
 
 72 
 
 136 
 
 137 
 
 94 
 
 92 
 
 91 
 
 89 
 
 88 
 
 86 
 
 84 
 
 83 
 
 81 
 
 79 
 
 78 
 
 76 
 
 74 
 
 137 
 
 138 
 
 95 
 
 93 
 
 92 
 
 90 
 
 89 
 
 87 
 
 86 
 
 84 
 
 82 
 
 81 
 
 79 
 
 77 
 
 75 
 
 138 
 
 139 
 
 96 
 
 95 
 
 93 
 
 92 
 
 90 
 
 89 
 
 87 
 
 85 
 
 84 
 
 82 
 
 80 
 
 79 
 
 77 
 
 139 
 
 140 
 
 97 
 
 96 
 
 94 
 
 93 
 
 91 
 
 90 
 
 88 
 
 87 
 
 85 
 
 83 
 
 82 
 
 80 
 
 78 
 
 140 
 
 t. 
 
 36.0 
 
 37. 
 
 38.0 
 
 39.0 
 
 40. 
 
 41.0 
 
 42.0 
 
 43. 
 
 44. 
 
 45 .0 
 
 46.0 
 
 47. 
 
 48.0 
 
 I. 
 
81 
 
 TABLE II. Relative humidity, per cent. 
 
 K. 
 
 Difference between the dry and wet thermometers (tf). 
 
 _i 
 
 b 
 
 0.2 
 
 0.4 
 
 0.6 
 
 0.8 
 
 10.0 
 
 10.. 
 
 10.4 
 
 10.6 
 
 1. 8 
 
 2.0 
 
 2. 2 
 
 2. 4 
 
 2. 6 
 
 "i 
 
 40 
 
 46 
 
 
 
 
 
 
 
 
 
 
 ~ 
 
 (<-<') 
 
 40 
 
 39 
 
 49 
 
 
 
 
 
 
 
 
 
 
 JT 
 
 
 39 
 
 38 
 
 51 
 
 
 
 
 
 
 
 
 
 
 
 
 
 38 
 
 37 
 
 54 
 
 
 
 
 
 
 
 
 
 
 b 
 
 0. 1 
 
 0.2 
 
 37 
 
 36 
 
 56 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 36 
 
 35 
 
 59 
 
 
 
 
 
 
 
 
 
 
 50 
 
 51 
 
 
 35 
 
 34 
 
 61 
 
 22 
 
 
 
 
 
 
 
 
 
 49 
 
 54 
 
 
 34 
 
 33 
 
 63 
 
 25 
 
 
 
 
 
 
 
 
 
 48 
 
 57 
 
 
 33 Rela- 
 
 32 
 31 
 
 65 
 67 
 
 30 
 34 
 
 
 
 
 
 
 
 
 
 47 
 
 46 
 
 60 
 
 62 
 
 
 -3? tivehu- 
 31 midity. 
 
 30 
 
 69 
 
 38 
 
 
 
 
 
 
 
 
 
 45 
 
 65 
 
 
 30 
 
 29 
 
 71 
 
 42 
 
 
 
 
 
 
 
 
 
 44 
 
 67 
 
 33 
 
 29 
 
 -28 
 
 72 
 
 45 
 
 17 
 
 
 
 
 
 
 
 
 43 
 
 69 
 
 37 
 
 28 
 
 27 
 
 74 
 
 48 
 
 22 
 
 
 
 
 
 
 
 
 42 
 
 71 
 
 40 
 
 27 
 
 -26 
 
 76 
 
 51 
 
 26 
 
 
 
 
 
 
 
 
 41 
 
 72 
 
 44 
 
 26 
 
 -25 
 
 77 
 
 53 
 
 31 
 
 
 
 
 
 
 
 
 40 
 
 73 
 
 46 
 
 25 
 
 -24 
 
 78 
 
 56 
 
 34 
 
 12 
 
 
 
 
 
 
 
 39 
 
 74 
 
 49 
 
 24 
 
 -23 
 
 79 
 
 58 
 
 37 
 
 16 
 
 
 
 
 
 
 
 38 
 
 76 
 
 51 
 
 23 
 
 22 
 
 80 
 
 60 
 
 40 
 
 20 
 
 
 
 
 
 
 
 37 
 
 77 
 
 54 
 
 22 
 
 21 
 
 81 
 
 62 
 
 44 
 
 25 
 
 
 
 
 
 
 
 36 
 
 78 
 
 56 
 
 21 
 
 20 
 
 82 
 
 64 
 
 47 
 
 29 
 
 11 
 
 
 
 
 
 
 35 
 
 79 
 
 59 
 
 20 
 
 19 
 
 83 
 
 66 
 
 49 
 
 33 
 
 16 
 
 
 
 
 
 
 34 
 
 80 
 
 61 
 
 19 
 
 18 
 
 84 
 
 68 
 
 52 
 
 36 
 
 20 
 
 
 
 
 
 
 -33 
 
 81 
 
 63 
 
 18 
 
 17 
 
 85 
 
 70 
 
 54 
 
 39 
 
 24 
 
 9 
 
 
 
 
 
 32 
 
 83 
 
 65 
 
 -17 
 
 16 
 
 86 
 
 71 
 
 57 
 
 43 
 
 28 
 
 14 
 
 
 
 
 
 31 
 
 84 
 
 67 
 
 16 
 
 15 
 
 1 A_ 
 
 86 
 
 73 
 
 59 
 
 46 
 
 AQ 
 
 32 
 
 Q 
 
 19 
 23 
 
 10 
 
 
 
 
 30 
 
 85 
 
 69 
 
 15 
 
 13 
 
 88 
 
 76 
 
 63 
 
 T:O 
 
 51 
 
 OD 
 
 39 
 
 27 
 
 15 
 
 
 
 
 
 
 
 13 
 
 12 
 
 88 
 
 77 
 
 65 
 
 53 
 
 42 
 
 30 
 
 19 
 
 7 
 
 
 
 
 
 
 12 
 
 11 
 
 89 
 
 78 
 
 67 
 
 56 
 
 45 
 
 34 
 
 23 
 
 12 
 
 
 
 
 
 
 11 
 
 10 
 
 90 
 
 79 
 
 68 
 
 58 
 
 48 
 
 37 
 
 26 
 
 16 
 
 5 
 
 
 
 
 
 10 
 
 9 
 
 90 
 
 80 
 
 70 
 
 60 
 
 50 
 
 40 
 
 30 
 
 20 
 
 10 
 
 
 
 
 
 9 
 
 8 
 
 90 
 
 81 
 
 71 
 
 62 
 
 52 
 
 '43 
 
 33 
 
 24 
 
 14 
 
 5 
 
 
 
 
 8 
 
 7 
 
 91 
 
 82 
 
 73 
 
 63 
 
 54 
 
 45 
 
 36 
 
 27 
 
 18 
 
 9 
 
 
 
 
 7 
 
 6 
 
 91 
 
 83 
 
 74 
 
 65 
 
 56 
 
 48 
 
 39 
 
 31 
 
 22 
 
 13 
 
 5 
 
 
 
 6 
 
 5 
 
 92 
 
 83 
 
 75 
 
 67 
 
 58 
 
 50 
 
 42 
 
 34 
 
 25 
 
 17 
 
 9 
 
 
 
 5 
 
 4 
 
 92 
 
 84 
 
 76 
 
 68 
 
 60 
 
 52 
 
 45 
 
 37 
 
 29 
 
 21 
 
 13 
 
 5 
 
 
 4 
 
 3 
 
 92 
 
 85 
 
 77 
 
 70 
 
 62 
 
 65 
 
 47 
 
 40 
 
 32 
 
 25 
 
 17 
 
 10 
 
 
 3 
 
 2 
 
 93 
 
 86 
 
 78 
 
 71 
 
 64 
 
 57 
 
 50 
 
 42 
 
 35 
 
 28 
 
 21 
 
 14 
 
 7 
 
 2 
 
 1 
 
 93 
 
 86 
 
 79 
 
 72 
 
 66 
 
 59 
 
 52 
 
 45 
 
 38 
 
 31 
 
 25 
 
 18 
 
 11 
 
 1 
 
 
 
 93 
 
 87 
 
 80 
 
 74 
 
 67 
 
 61 
 
 54 
 
 48 
 
 41 
 
 35 
 
 28 
 
 22 
 
 15 
 
 
 
 + 1 
 
 94 
 
 87 
 
 81 
 
 75 
 
 69 
 
 63 
 
 56 
 
 50 
 
 44 
 
 38 
 
 32 
 
 25 
 
 19 
 
 + 1 
 
 2 
 
 94 
 
 88 
 
 82 
 
 76 
 
 70 
 
 64 
 
 58 
 
 52 
 
 46 
 
 40 
 
 35 
 
 29 
 
 23 
 
 2 
 
 3 
 
 94 
 
 88 
 
 83 
 
 77 
 
 71 
 
 66 
 
 60 
 
 54 
 
 49 
 
 43 
 
 37 
 
 32 
 
 26 
 
 3 
 
 4 
 
 94 
 
 89 
 
 83 
 
 78 
 
 73 
 
 67 
 
 62 
 
 56 
 
 51 
 
 45 
 
 40 
 
 34 
 
 29 
 
 4 
 
 5 
 
 95 
 
 89 
 
 84 
 
 79 
 
 74 
 
 68 
 
 63 
 
 58 
 
 53 
 
 48 
 
 42 
 
 3.7 
 
 32 
 
 5 
 
 6 
 
 95 
 
 90 
 
 85 
 
 80 
 
 75 
 
 70 
 
 65 
 
 60 
 
 54 
 
 50 
 
 44 
 
 39 
 
 34 
 
 6 
 
 7 
 
 95 
 
 90 
 
 85 
 
 80 
 
 76 
 
 71 
 
 66 
 
 61 
 
 56 
 
 51 
 
 47 
 
 42 
 
 37 
 
 7 
 
 8 
 
 95 
 
 91 
 
 86 
 
 81 
 
 76 
 
 72 
 
 67 
 
 62 
 
 58 
 
 53 
 
 49 
 
 44 
 
 39 
 
 8 
 
 9 
 
 96 
 
 91 
 
 86 
 
 82 
 
 77 
 
 73 
 
 68 
 
 64 
 
 59 
 
 55 
 
 51 
 
 46 
 
 42 
 
 9 
 
 10 
 
 96 
 
 91 
 
 87 
 
 83 
 
 78 
 
 74 
 
 69 
 
 65 
 
 61 
 
 57 
 
 52 
 
 48 
 
 44 
 
 10 
 
 It 
 
 96 
 
 92 
 
 87 
 
 83 
 
 79 
 
 75 
 
 71 
 
 66 
 
 62 
 
 58 
 
 54 
 
 50 
 
 46 
 
 11 
 
 12 
 
 90 
 
 92 
 
 88 
 
 84 
 
 80 
 
 76 
 
 72 
 
 68 
 
 64 
 
 60 
 
 56 
 
 52 
 
 48 
 
 12 
 
 13 
 
 96 
 
 92 
 
 88 
 
 84 
 
 81 
 
 77 
 
 73 
 
 69 
 
 65 
 
 61 
 
 58 
 
 54 
 
 50 
 
 13 
 
 14 
 
 96 
 
 93 
 
 89 
 
 85 
 
 81 
 
 78 
 
 74 
 
 70 
 
 67 
 
 63 
 
 59 
 
 56 
 
 52 
 
 14 
 
 15 
 
 96 
 
 93 
 
 89 
 
 86 
 
 82 
 
 79 
 
 75 
 
 71 
 
 68 
 
 64 
 
 61 
 
 57 
 
 54 
 
 15 
 
 16 
 
 97 
 
 93 
 
 90 
 
 8G 
 
 83 
 
 79 
 
 76 
 
 73 
 
 69 
 
 66 
 
 62 
 
 59 
 
 56 
 
 16 
 
 17 
 
 97 
 
 93 
 
 90 
 
 87 
 
 83 
 
 80 
 
 77 
 
 74 
 
 70 
 
 67 
 
 64 
 
 60 
 
 57 
 
 17 
 
 18 
 
 97 
 
 94 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 74 
 
 71 
 
 68 
 
 65 
 
 62 
 
 59 
 
 18 
 
 19 
 
 97 
 
 94 
 
 91 
 
 88 
 
 84 
 
 81 
 
 78 
 
 75 
 
 72 
 
 69 
 
 66 
 
 63 
 
 60 
 
 19 
 
 20 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 79 
 
 76 
 
 73 
 
 70 
 
 67 
 
 64 
 
 61 
 
 20 
 
 t. 
 
 0.2 
 
 0.4 
 
 0.6 
 
 0.8 
 
 1. 
 
 ,. 2 
 
 10.4 
 
 P. 6 
 
 ,0.8 
 
 2.0 
 
 2.2 
 
 2. 4 
 
 2. 6 
 
 t. 
 
82 
 
 TABLE II. Relative humidity, per cent. 
 
 I 
 
 Difference between the dry and wet thermometers (t <') 
 
 
 
 p. 
 
 2. 6 
 
 2. 8 
 
 3.0 
 
 3. 2 
 
 3. 4 
 
 3. 6 
 
 3. 8 
 
 4.0 
 
 4. 2 
 
 4. 4 
 
 1 
 
 2 
 
 7 
 
 
 
 
 
 
 
 
 
 
 2 
 
 1 
 
 11 
 
 4 
 
 
 
 
 
 
 
 
 
 1 
 
 o 
 
 15 
 
 9 
 
 
 
 
 
 
 
 
 
 
 
 + 1 
 
 19 
 
 13 
 
 7 
 
 
 
 
 
 
 
 
 -f 1 
 
 2 
 
 23 
 
 17 
 
 11 
 
 5 
 
 
 
 
 
 
 
 2 
 
 3 
 
 26 
 
 20 
 
 15 
 
 9 
 
 4 
 
 
 
 
 
 
 3 
 
 4 
 
 29 
 
 24 
 
 18 
 
 13 
 
 8 
 
 2 
 
 
 
 
 
 4 
 
 5 
 
 32 
 
 27 
 
 22 
 
 16 
 
 11 
 
 6 
 
 
 
 
 
 5 
 
 6 
 
 34 
 
 29 
 
 25 
 
 20 
 
 15 
 
 10 
 
 5 
 
 
 
 
 6 
 
 7 
 
 37 
 
 32 
 
 28 
 
 23 
 
 18 
 
 13 
 
 9 
 
 4 
 
 
 
 7 
 
 8 
 
 39 
 
 35 
 
 30 
 
 26 
 
 21 
 
 17 
 
 12 
 
 8 
 
 3 
 
 
 8 
 
 9 
 
 42 
 
 37 
 
 33 
 
 28 
 
 24 
 
 20 
 
 15 
 
 11 
 
 7 
 
 2 
 
 9 
 
 10 
 
 44 
 
 40 
 
 35 
 
 31 
 
 27 
 
 23 
 
 19 
 
 14 
 
 10 
 
 6 
 
 10 
 
 11 
 
 46 
 
 42 
 
 38 
 
 34 
 
 30 
 
 26 
 
 22 
 
 18 
 
 14 
 
 10 
 
 11 
 
 12 
 
 48 
 
 44 
 
 40 
 
 36 
 
 32 
 
 28 
 
 25 
 
 21 
 
 17 
 
 13 
 
 12 
 
 13 
 
 50 
 
 46 
 
 42 
 
 39 
 
 35 
 
 31 
 
 27 
 
 24 
 
 20 
 
 16 
 
 13 
 
 14 
 
 52 
 
 48 
 
 45 
 
 41 
 
 37 
 
 34 
 
 30 
 
 27 
 
 23 
 
 19 
 
 14 
 
 15 
 
 54 
 
 50 
 
 47 
 
 43 
 
 40 
 
 36 
 
 33 
 
 29 
 
 26 
 
 23 
 
 15 
 
 16 
 
 56 
 
 52 
 
 49 
 
 46 
 
 42 
 
 39 
 
 36 
 
 32 
 
 29 
 
 25 
 
 16 
 
 17 
 
 57 
 
 54 
 
 51 
 
 48 
 
 44 
 
 41 
 
 38 
 
 35 
 
 31 
 
 28 
 
 17 
 
 18 
 
 59 
 
 56 
 
 53 
 
 49 
 
 46 
 
 43 
 
 40 
 
 37 
 
 34 
 
 31 
 
 18 
 
 19 
 
 60 
 
 57 
 
 54 
 
 51 
 
 48 
 
 45 
 
 42 
 
 39 
 
 36 
 
 33 
 
 19 
 
 20 
 
 61 
 
 58 
 
 56 
 
 53 
 
 50 
 
 47 
 
 44 
 
 41 
 
 38 
 
 '35 
 
 20 
 
 t. 
 
 2. 6 
 
 2.8 
 
 3.0 
 
 3. 2 
 
 3. 4 
 
 3. 6 
 
 3. 8 
 
 4.0 
 
 4. 2 
 
 4. 4 
 
 t. 
 
 t. 
 
 4. 6 
 
 4. 8 
 
 5.0 
 
 5. 2 
 
 5. 4 
 
 5. 6 
 
 5. 8 
 
 6.0 
 
 6. 2 
 
 6. 4 
 
 t. 
 
 8 
 
 
 
 
 
 
 
 
 
 
 
 8 
 
 9 
 
 
 
 
 
 
 
 
 
 
 
 9 
 
 10 
 
 2 
 
 
 
 
 
 
 
 
 
 
 10 
 
 11 
 
 6 
 
 2 
 
 
 
 
 
 
 
 
 
 11 
 
 12 
 
 9 
 
 5 
 
 2 
 
 
 
 
 
 
 
 
 12 
 
 13 
 
 13 
 
 9 
 
 5 
 
 2 
 
 
 
 
 
 
 
 13 
 
 14 
 
 16 
 
 12 
 
 9 
 
 5 
 
 2 
 
 
 
 
 
 
 14 
 
 15 
 
 19 
 
 16 
 
 12 
 
 9 
 
 5 
 
 2 
 
 
 
 
 
 15 
 
 16 
 
 22 
 
 19 
 
 16 
 
 12 
 
 9 
 
 6 
 
 2 
 
 
 
 
 16 
 
 17 
 
 25 
 
 22 
 
 19 
 
 16 
 
 12 
 
 9 
 
 6 
 
 3 
 
 
 
 17 
 
 18 
 
 28 
 
 25 
 
 22 
 
 19 
 
 16 
 
 13 
 
 9 
 
 6 
 
 3 
 
 
 18 
 
 19 
 
 30 
 
 27 
 
 24 
 
 21 
 
 19 
 
 16 
 
 13 
 
 10 
 
 7 
 
 4 
 
 19 
 
 20 
 
 33 
 
 30 
 
 27 
 
 24 
 
 21 
 
 19 
 
 16 
 
 13 
 
 10 
 
 7 
 
 20 
 
 t. 
 
 4. 6 
 
 4. 8 
 
 5.0 
 
 5. 2 
 
 5. 4 
 
 5. 6 
 
 5. 8 
 
 6.0 
 
 6^.2 
 
 6. 4 
 
 t. 
 
83 
 
 TABLE II. Relative humidity, per cent. 
 
 X5 
 
 Difference between the dry and wet thermometers (t t'). 
 
 1 
 
 I 
 
 0.5 
 
 10.0 
 
 10.5 
 
 2.0 
 
 2. 5 
 
 3.0 
 
 3. 5 
 
 4.0 
 
 4. 5 
 
 5.0 
 
 5. 5 
 
 6.0 
 
 1 
 
 20 
 
 92 
 
 85 
 
 77 
 
 70 
 
 63 
 
 56 
 
 48 
 
 41 
 
 34 
 
 27 
 
 20 
 
 13 
 
 20 
 
 21 
 
 93 
 
 85 
 
 78 
 
 71 
 
 64 
 
 57 
 
 50 
 
 43 
 
 36 
 
 29 
 
 23 
 
 16 
 
 21 
 
 22 
 
 93 
 
 86 
 
 79 
 
 72 
 
 65 
 
 58 
 
 51 
 
 45 
 
 38 
 
 32 
 
 25 
 
 19 
 
 22 
 
 23 
 
 93 
 
 86 
 
 80 
 
 73 
 
 66 
 
 60 
 
 53 
 
 46 
 
 40 
 
 34 
 
 27 
 
 21 
 
 23 
 
 24 
 
 93 
 
 87 
 
 80 
 
 74 
 
 67 
 
 61 
 
 54 
 
 48 
 
 42 
 
 36 
 
 30 
 
 24 
 
 24 
 
 25 
 
 94 
 
 87 
 
 81 
 
 74 
 
 68 
 
 62 
 
 56 
 
 50 
 
 44 
 
 38 
 
 32 
 
 26 
 
 25 
 
 26 
 
 94 
 
 88 
 
 81 
 
 75 
 
 69 
 
 63 
 
 57 
 
 51 
 
 45 
 
 40 
 
 34 
 
 28 
 
 26 
 
 27 
 
 94 
 
 88 
 
 82 
 
 76 
 
 70 
 
 64 
 
 59 
 
 53 
 
 47 
 
 42 
 
 36 
 
 30 
 
 27 
 
 28 
 
 94 
 
 88 
 
 82 
 
 77 
 
 71 
 
 65 
 
 GO 
 
 54 
 
 49 
 
 43 
 
 38 
 
 33 
 
 28 
 
 29 
 
 94 
 
 89 
 
 83 
 
 77 
 
 72 
 
 66 
 
 61 
 
 56 
 
 50 
 
 45 
 
 40 
 
 35 
 
 29 
 
 30 
 
 94 
 
 89 
 
 84 
 
 78 
 
 73 
 
 67 
 
 62 
 
 57 
 
 52 
 
 47 
 
 41 
 
 36 
 
 30 
 
 31 
 
 95 
 
 89 
 
 84 
 
 79 
 
 74 
 
 68 
 
 63 
 
 58 
 
 53 
 
 48 
 
 43 
 
 38 
 
 31 
 
 32 
 
 95 
 
 90 
 
 84 
 
 79 
 
 74 
 
 69 
 
 64 
 
 59 
 
 54 
 
 50 
 
 45 
 
 40 
 
 32 
 
 33 
 
 95 
 
 90 
 
 85 
 
 80 
 
 75 
 
 70 
 
 65 
 
 60 
 
 56 
 
 51 
 
 47 
 
 42 
 
 33 
 
 34 
 
 95 
 
 91 
 
 86 
 
 81 
 
 75 
 
 72 
 
 67 
 
 62 
 
 57 
 
 53 
 
 48 
 
 44 
 
 34 
 
 35 
 
 95 
 
 91 
 
 86 
 
 82 
 
 76 
 
 73 
 
 69 
 
 65 
 
 59 
 
 54 
 
 50 
 
 45 
 
 35 
 
 36 
 
 96 
 
 91 
 
 86 
 
 82 
 
 77 
 
 73 
 
 70 
 
 66 
 
 61 
 
 56 
 
 51 
 
 47 
 
 36 
 
 37 
 
 96 
 
 91 
 
 87 
 
 82 
 
 78 
 
 74 
 
 70 
 
 66 
 
 62 
 
 57 
 
 52 
 
 48 
 
 37 
 
 38 
 
 96 
 
 92 
 
 87 
 
 83 
 
 79 
 
 75 
 
 71 
 
 67 
 
 63 
 
 58 
 
 54 
 
 50 
 
 38 
 
 39 
 
 96 
 
 9'^ 
 
 88 
 
 83 
 
 79 
 
 75 
 
 72 
 
 68 
 
 63 
 
 59 
 
 55 
 
 52 
 
 39 
 
 40 
 
 96 
 
 92 
 
 88 
 
 84 
 
 80 
 
 76 
 
 72 
 
 68 
 
 64 
 
 60 
 
 56 
 
 53 
 
 40 
 
 41 
 
 96 
 
 92 
 
 88 
 
 84 
 
 80 
 
 76 
 
 72 
 
 69 
 
 65 
 
 61 
 
 57 
 
 54 
 
 41 
 
 42 
 
 96 
 
 92 
 
 88 
 
 84 
 
 81 
 
 77 
 
 73 
 
 69 
 
 65 
 
 62 
 
 58 
 
 55 
 
 42 
 
 43 
 
 96 
 
 92 
 
 88 
 
 85 
 
 81 
 
 77 
 
 74 
 
 70 
 
 66 
 
 63 
 
 59 
 
 56 
 
 43 
 
 44 
 
 96 
 
 92 
 
 88 
 
 85 
 
 81 
 
 78 
 
 74 
 
 70 
 
 67 
 
 63 
 
 60 
 
 57 
 
 44 
 
 45 
 
 96 
 
 92 
 
 89 
 
 85 
 
 82 
 
 78 
 
 75 
 
 71 
 
 67 
 
 64 
 
 61 
 
 58 
 
 45 
 
 46 
 
 96 
 
 93 
 
 89 
 
 85 
 
 82 
 
 79 
 
 75 
 
 72 
 
 68 
 
 65 
 
 61 
 
 58 
 
 46 
 
 47 
 
 96 
 
 93 
 
 89 
 
 86 
 
 83 
 
 79 
 
 76 
 
 72 
 
 69 
 
 66 
 
 62 
 
 59 
 
 47 
 
 48 
 
 96 
 
 93 
 
 89 
 
 86 
 
 83 
 
 79 
 
 76 
 
 73 
 
 69 
 
 66 
 
 63 
 
 60 
 
 48 
 
 49 
 
 97 
 
 93 
 
 90 
 
 86 
 
 83 
 
 80 
 
 76 
 
 73 
 
 70 
 
 67 
 
 63 
 
 60 
 
 49 
 
 50 
 
 97 
 
 93 
 
 90 
 
 87 
 
 83 
 
 80 
 
 77 
 
 74 
 
 70 
 
 67 
 
 64 
 
 61 
 
 50 
 
 51 
 
 97 
 
 93 
 
 90 
 
 87 
 
 84 
 
 81 
 
 77 
 
 74 
 
 71 
 
 68 
 
 65 
 
 62 
 
 51 
 
 52 
 
 97 
 
 94 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 75 
 
 72 
 
 69 
 
 66 
 
 63 
 
 52 
 
 53 
 
 97 
 
 94 
 
 91 
 
 87 
 
 84 
 
 81 
 
 78 
 
 75 
 
 72 
 
 69 
 
 66 
 
 65 
 
 53 
 
 54 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 79 
 
 76 
 
 73 
 
 70 
 
 67 
 
 64 
 
 54 
 
 55 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 79 
 
 76 
 
 73 
 
 70 
 
 68 
 
 65 
 
 55 
 
 56 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 80 
 
 77 
 
 74 
 
 71 
 
 68 
 
 65 
 
 56 
 
 57 
 
 97 
 
 94 
 
 91 
 
 88 
 
 86 
 
 83 
 
 80 
 
 77 
 
 74 
 
 71 
 
 69 
 
 66 
 
 57 
 
 58 
 
 97 
 
 94 
 
 91 
 
 89 
 
 86 
 
 83 
 
 80 
 
 78 
 
 75 
 
 72 
 
 69 
 
 67 
 
 58 
 
 59 
 
 97 
 
 94 
 
 92 
 
 89 
 
 86 
 
 83 
 
 81 
 
 78 
 
 75 
 
 72 
 
 70 
 
 67 
 
 59 
 
 60 
 
 97 
 
 94 
 
 92 
 
 89 
 
 86 
 
 84 
 
 81 
 
 78 
 
 75 
 
 73 
 
 70 
 
 68 
 
 60 
 
 61 
 
 97 
 
 94 
 
 92 
 
 89 
 
 87 
 
 84 
 
 81 
 
 78 
 
 76 
 
 73 
 
 71 
 
 68 
 
 61 
 
 62 
 
 97 
 
 95 
 
 92 
 
 89 
 
 87 
 
 84 
 
 81 
 
 79 
 
 76 
 
 74 
 
 71 
 
 69 
 
 62 
 
 63 
 
 97 
 
 95 
 
 92 
 
 89 
 
 87 
 
 84 
 
 82 
 
 79 
 
 77 
 
 74 
 
 72 
 
 69 
 
 63 
 
 64 
 
 97 
 
 95 
 
 9-2 
 
 90 
 
 87 
 
 85 
 
 82 
 
 79 
 
 77 
 
 74 
 
 72 
 
 70 
 
 64 
 
 65 
 
 97 
 
 95 
 
 92 
 
 90 
 
 87 
 
 85 
 
 82 
 
 80 
 
 77 
 
 75 
 
 72 
 
 70 
 
 65 
 
 66 
 
 97 
 
 95 
 
 92 
 
 90 
 
 87 
 
 85 
 
 82 
 
 80 
 
 78 
 
 75 
 
 73 
 
 71 
 
 66 
 
 67 
 
 98 
 
 95 
 
 93 
 
 90 
 
 88 
 
 85 
 
 83 
 
 80 
 
 78 
 
 76 
 
 73 
 
 71 
 
 67 
 
 68 
 
 98 
 
 95 
 
 93 
 
 90 
 
 88 
 
 85 
 
 83 
 
 81 
 
 78 
 
 76 
 
 74 
 
 71 
 
 68 
 
 69 
 
 98 
 
 95 
 
 93 
 
 90 
 
 88 
 
 86 
 
 83 
 
 81 
 
 78 
 
 76 
 
 74 
 
 72 
 
 69 
 
 70 
 
 98 
 
 95 
 
 93 
 
 90 
 
 88 
 
 86 
 
 83 
 
 81 
 
 79 
 
 77 
 
 74 
 
 72 
 
 70 
 
 71 
 
 98 
 
 95 
 
 93 
 
 91 
 
 88 
 
 86 
 
 84 
 
 81 
 
 79 
 
 77 
 
 75 
 
 72 
 
 71 
 
 72 
 
 98 
 
 95 
 
 93 
 
 91 
 
 88 
 
 86 
 
 84 
 
 82 
 
 79 
 
 77 
 
 75 
 
 73 
 
 72 
 
 73 
 
 98 
 
 95 
 
 93 
 
 91 
 
 88 
 
 86 
 
 84 
 
 82 
 
 80 
 
 78 
 
 75 
 
 73 
 
 73 
 
 74 
 
 98 
 
 95 
 
 93 
 
 91 
 
 88 
 
 86 
 
 84 
 
 82 
 
 80 
 
 78 
 
 76 
 
 74 
 
 74 
 
 75 
 
 98 
 
 95 
 
 93 
 
 91 
 
 89 
 
 87 
 
 84 
 
 82 
 
 80 
 
 78 
 
 76 
 
 74 
 
 75 
 
 76 
 
 98 
 
 95 
 
 93 
 
 91 
 
 89 
 
 87 
 
 85 
 
 82 
 
 80 
 
 78 
 
 76 
 
 74 
 
 76 
 
 77 
 
 98 
 
 95 
 
 93 
 
 91 
 
 89 
 
 87 
 
 85 
 
 83 
 
 80 
 
 78 
 
 76 
 
 74 
 
 77 
 
 78 
 
 98 
 
 96 
 
 93 
 
 91 
 
 89 
 
 87 
 
 85 
 
 83 
 
 81 
 
 79 
 
 77 
 
 75 
 
 78 
 
 79 
 
 98 
 
 96 
 
 94 
 
 91 
 
 89 
 
 87 
 
 85 
 
 83 
 
 81 
 
 79 
 
 77 
 
 75 
 
 79 
 
 80 
 
 98 
 
 96 
 
 94 
 
 92 
 
 89 
 
 87 
 
 85 
 
 83 
 
 81 
 
 79 
 
 77 
 
 75 
 
 80 
 
 t. 
 
 0.5 
 
 iM 
 
 *. 
 
 2.0 
 
 2. 5 
 
 3.0 
 
 3. 5 
 
 4.0 
 
 4. 5 
 
 6.0 
 
 5. 5 
 
 6.0 
 
 .t 
 
 9377 
 
84 
 
 TABLE II. Relative humidity, per cent. 
 
 t 
 
 (Dryther.) 
 
 Difference between the dry and wet thermometers (t t'). 
 
 t 
 (Dry ther.) 
 
 \ 
 6.0 
 
 6. 5 
 
 7.0 
 
 7.5 
 
 8.0 
 
 8.5 
 
 9.0 
 
 9.5 
 
 10.0 
 
 10. 5 
 
 11.0 
 
 11.5 
 
 12.0 
 
 19 
 
 10 
 
 
 
 
 
 
 
 
 
 
 
 
 
 19 
 
 20 
 
 13 
 
 6 
 
 
 
 
 
 
 
 
 
 
 
 
 20 
 
 21 
 
 16 
 
 9 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 21 
 
 22 
 
 19 
 
 12 
 
 6 
 
 
 
 
 
 
 
 
 
 
 
 22 
 
 23 
 
 21 
 
 15 
 
 9 
 
 2 
 
 
 
 
 
 
 
 
 
 
 23 
 
 24 
 
 24 
 
 17 
 
 11 
 
 6 
 
 
 
 
 
 
 
 
 
 
 24 
 
 25 
 
 26 
 
 20 
 
 14 
 
 8 
 
 3 
 
 
 
 
 
 
 
 
 
 25 
 
 26 
 
 28 
 
 23 
 
 17 
 
 11 
 
 6 
 
 
 
 
 
 
 
 
 
 26 
 
 27 
 
 30 
 
 25 
 
 19 
 
 14 
 
 9 
 
 3 
 
 
 
 
 
 
 
 
 27 
 
 28 
 
 33 
 
 27 
 
 22 
 
 17 
 
 11 
 
 6 
 
 1 
 
 
 
 
 
 
 
 28 
 
 29 
 
 35 
 
 29 
 
 24 
 
 19 
 
 14 
 
 9 
 
 4 
 
 
 
 
 
 
 
 29 
 
 30 
 
 36 
 
 31 
 
 26 
 
 22 
 
 17 
 
 12 
 
 7 
 
 2 
 
 
 
 
 
 
 30 
 
 31 
 
 38 
 
 33 
 
 29 
 
 24 
 
 19 
 
 14 
 
 10 
 
 5 
 
 
 
 
 
 
 31 
 
 32 
 
 40 
 
 35 
 
 31 
 
 26 
 
 21 
 
 17 
 
 12 
 
 8 
 
 3 ' 
 
 
 
 
 
 32 
 
 33 
 
 42 
 
 37 
 
 33 
 
 28 
 
 24 
 
 19 
 
 15 
 
 10 
 
 6 
 
 2 
 
 
 
 
 33 
 
 34 
 
 44 
 
 39 
 
 35 
 
 30 
 
 26 
 
 21 
 
 17 
 
 13 
 
 9 
 
 4 
 
 
 
 
 34 
 
 35 
 
 45 
 
 41 
 
 37 
 
 32 
 
 28 
 
 24 
 
 19 
 
 15 
 
 12 
 
 7 
 
 3 
 
 
 
 35 
 
 36 
 
 47 
 
 43 
 
 38 
 
 34 
 
 30 
 
 26 
 
 22 
 
 18 
 
 14 
 
 10 
 
 6 
 
 2 
 
 
 36 
 
 37 
 
 48 
 
 44 
 
 40 
 
 36 
 
 32' 
 
 28 
 
 24 
 
 20 
 
 16 
 
 12 
 
 8 
 
 5 
 
 1 
 
 37 
 
 38 
 
 50 
 
 46 
 
 42 
 
 38 
 
 34 
 
 30 
 
 26 
 
 22 
 
 18 
 
 15 
 
 11 
 
 7 
 
 3 
 
 38 
 
 39 
 
 52 
 
 48 
 
 44 
 
 40 
 
 36 
 
 32 
 
 28 
 
 24 
 
 20 
 
 17 
 
 13 
 
 9 
 
 6 
 
 39 
 
 40 
 
 53 
 
 49 
 
 45 
 
 41 
 
 38 
 
 34 
 
 30 
 
 26 
 
 22 
 
 19 
 
 16 
 
 12 
 
 8 
 
 40 
 
 41 
 
 54 
 
 50 
 
 46 
 
 43 
 
 39 
 
 36 
 
 32 
 
 29 
 
 24 
 
 21 
 
 18 
 
 14 
 
 10 
 
 41 
 
 42 
 
 55 
 
 51 
 
 48 
 
 44 
 
 40 
 
 37 
 
 34 
 
 30 
 
 27 
 
 23 
 
 20 
 
 16 
 
 13 
 
 42 
 
 43 
 
 56 
 
 52 
 
 49 
 
 46 
 
 42 
 
 38 
 
 35 
 
 32 
 
 29 
 
 25 
 
 22 
 
 19 
 
 15 
 
 43 
 
 44 
 
 57 
 
 53 
 
 50 
 
 47 
 
 43 
 
 40 
 
 37 
 
 33 
 
 30 
 
 27 
 
 24 
 
 21 
 
 17 
 
 44 
 
 45 
 
 58 
 
 54 
 
 51 
 
 48 
 
 44 
 
 41 
 
 38 
 
 35 
 
 32 
 
 29 
 
 25 
 
 22 
 
 19 
 
 45 
 
 46 
 
 58 
 
 55 
 
 52 
 
 49 
 
 46 
 
 42 
 
 39 
 
 36 
 
 33 
 
 30 
 
 27 
 
 23 
 
 21 
 
 46 
 
 47 
 
 59 
 
 56 
 
 63 
 
 50 
 
 47 
 
 44 
 
 40 
 
 38 
 
 34 
 
 31 
 
 28 
 
 25 
 
 22 
 
 47 
 
 48 
 
 60 
 
 56 
 
 53 
 
 51 
 
 48 
 
 45 
 
 42 
 
 39 
 
 36 
 
 33 
 
 30 
 
 27 
 
 24 
 
 48 
 
 49 
 
 60 
 
 57 
 
 54 
 
 52 
 
 49 
 
 46 
 
 43 
 
 40 
 
 37 
 
 34 
 
 31 
 
 29 
 
 26 
 
 49 
 
 50 
 
 61 
 
 58 
 
 55 
 
 52 
 
 50 
 
 47 
 
 44 
 
 41 
 
 38 
 
 36 
 
 33 
 
 30 
 
 27 
 
 50 
 
 51 
 
 62 
 
 69 
 
 56 
 
 53 
 
 50 
 
 48 
 
 45 
 
 42 
 
 39 
 
 37 
 
 34 
 
 31 
 
 28 
 
 51 
 
 52 
 
 63 
 
 60 
 
 57 
 
 54 
 
 51 
 
 48 
 
 46 
 
 43 
 
 40 
 
 38 
 
 35 
 
 33 
 
 30 
 
 52 
 
 53 
 
 63 
 
 61 
 
 58 
 
 55 
 
 52 
 
 49 
 
 47 
 
 44 
 
 42 
 
 39 
 
 36 
 
 34 
 
 31 
 
 53 
 
 54 
 
 64 
 
 61 
 
 59 
 
 56 
 
 53 
 
 50 
 
 48 
 
 45 
 
 43 
 
 40 
 
 38 
 
 35 
 
 32 
 
 54 
 
 55 
 
 65 
 
 62 
 
 59 
 
 57 
 
 54 
 
 51 
 
 49 
 
 46 
 
 43 
 
 41 
 
 39 
 
 36 
 
 34 
 
 55 
 
 56 
 
 65 
 
 63 
 
 60 
 
 57 
 
 55 
 
 52 
 
 50 
 
 47 
 
 44 
 
 42 
 
 40 
 
 37 
 
 35 
 
 56 
 
 57 
 
 66 
 
 64 
 
 61 
 
 58 
 
 55 
 
 53 
 
 50 
 
 48 
 
 45 
 
 43 
 
 40 
 
 38 
 
 36 
 
 57 
 
 58 
 
 67 
 
 64 
 
 61 
 
 59 
 
 56 
 
 53 
 
 51 
 
 49 
 
 46 
 
 44 
 
 42 
 
 39 
 
 37 
 
 58 
 
 69 
 
 67 
 
 65 
 
 62 
 
 60 
 
 57 
 
 54 
 
 52 
 
 49 
 
 47 
 
 45 
 
 43 
 
 40 
 
 38 
 
 59 
 
 60 
 
 68 
 
 65 
 
 63 
 
 60 
 
 58 
 
 55 
 
 53 
 
 50 
 
 48 
 
 46 
 
 44 
 
 41 
 
 39 
 
 60 
 
 61 
 
 68 
 
 66 
 
 63 
 
 61 
 
 58 
 
 56 
 
 54 
 
 51 
 
 49 
 
 47 
 
 44 
 
 42 
 
 40 
 
 61 
 
 62 
 
 69 
 
 66 
 
 64 
 
 61 
 
 59 
 
 57 
 
 54 
 
 52 
 
 50 
 
 47 
 
 45 
 
 43 
 
 41 
 
 62 
 
 63 
 
 69 
 
 67 
 
 64 
 
 62 
 
 60 
 
 57 
 
 55 
 
 53 
 
 51 
 
 48 
 
 46 
 
 44 
 
 42 
 
 63 
 
 64 
 
 70 
 
 67 
 
 65 
 
 62 
 
 60 
 
 58 
 
 56 
 
 53 
 
 51 
 
 49 
 
 47 
 
 45 
 
 43 
 
 64 
 
 65 
 
 70 
 
 68 
 
 65 
 
 63 
 
 61 
 
 59 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 44 
 
 65 
 
 66 
 
 71 
 
 68 
 
 66 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 45 
 
 66 
 
 67 
 
 71 
 
 69 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 45 
 
 67 
 
 68 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 68 
 
 69 
 
 72 
 
 70 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 69 
 
 70 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 57 
 
 55 
 
 53 
 
 52 
 
 50 
 
 48 
 
 70 
 
 71 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 71 
 
 72 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 72 
 
 73 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 52 
 
 50 
 
 73 
 
 74 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 74 
 
 75 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 55 
 
 53 
 
 51 
 
 75 
 
 76 
 
 74 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 63 
 
 61 
 
 sa 
 
 57 
 
 55 
 
 53 
 
 52 
 
 76 
 
 77 
 
 74 
 
 73. 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 56 
 
 54 
 
 52 
 
 77 
 
 78 
 
 75 
 
 73 
 
 71 
 
 69 
 
 67 
 
 65 
 
 63 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 53 
 
 78 
 
 79 
 
 75 
 
 73 
 
 71 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 57 
 
 55 
 
 53 
 
 79 
 
 80 
 
 75 
 
 73 
 
 72 
 
 70 
 
 68 
 
 66 
 
 64 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 54 
 
 80 
 
 f. 
 
 6.0 
 
 6.5 
 
 7 e .O 
 
 7.5 
 
 8.0 
 
 8.5 
 
 9.0 
 
 9.5 
 
 10.0 
 
 10.5 
 
 11.0 
 
 11.5 
 
 12.0 
 
 t. 
 
85 
 
 TABLE II. Relative humidity, per cent. 
 
 I 
 
 Difference between the dry and wet thermometers (< O. 
 
 |j 
 
 
 
 JS 
 
 (^ 
 
 12. 
 
 12. 5 
 
 13. 
 
 13. 5 
 
 14. 
 
 14. 5 
 
 15. 
 
 15. 5 
 
 16. 
 
 16. 5 
 
 17. 
 
 17. 5 
 
 18. 
 
 >> 
 
 . 
 
 40 
 
 8 
 
 5 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 40 
 
 41 
 
 10 
 
 7 
 
 4 
 
 
 
 
 
 
 
 
 
 
 
 41 
 
 42 
 
 13 
 
 10 
 
 6 
 
 3 
 
 
 
 
 
 
 
 
 
 
 42 
 
 43 
 
 15 
 
 12 
 
 9 
 
 5 
 
 2 
 
 
 
 
 
 
 
 
 
 43 
 
 44 
 
 17 
 
 14 
 
 11 
 
 8 
 
 5 
 
 1 
 
 
 
 
 
 
 
 
 44 
 
 45 
 
 19 
 
 16 
 
 13 
 
 10 
 
 7 
 
 4 
 
 1 
 
 
 
 
 
 
 
 45 
 
 46 
 
 21 
 
 18 
 
 15 
 
 12 
 
 9 
 
 6 
 
 3 
 
 
 
 
 
 
 
 46 
 
 47 
 
 22 
 
 20 
 
 16 
 
 14 
 
 11 
 
 8 
 
 5 
 
 3 
 
 
 
 
 
 
 47 
 
 48 
 
 24 
 
 21 
 
 19 
 
 16 
 
 13 
 
 10 
 
 7 
 
 5 
 
 2 
 
 
 
 
 
 48 
 
 49 
 
 26 
 
 23 
 
 20 
 
 17 
 
 15 
 
 12 
 
 9 
 
 7 
 
 4 
 
 1 
 
 
 
 
 49 
 
 50 
 
 27 
 
 24 
 
 22 
 
 19 
 
 16 
 
 14 
 
 11 
 
 9 
 
 6 
 
 4 
 
 1 
 
 
 
 50 
 
 61 
 
 28 
 
 26 
 
 23 
 
 21 
 
 18 
 
 16 
 
 13 
 
 10 
 
 8 
 
 5 
 
 3 
 
 
 
 
 51 
 
 52 
 
 30 
 
 27 
 
 24 
 
 22 
 
 20 
 
 17 
 
 15 
 
 12 
 
 10 
 
 7 
 
 5 
 
 2 
 
 
 52 
 
 63 
 
 31 
 
 29 
 
 26 
 
 24 
 
 21 
 
 19 
 
 16 
 
 14 
 
 12 
 
 9 
 
 7 
 
 4 
 
 2 
 
 53 
 
 54 
 
 32 
 
 30 
 
 28 
 
 25 
 
 23 
 
 20 
 
 18 
 
 15 
 
 13 
 
 11 
 
 8 
 
 6 
 
 4 
 
 54 
 
 55 
 
 34 
 
 31 
 
 29 
 
 26 
 
 24 
 
 22 
 
 19 
 
 17 
 
 15 
 
 12 
 
 10 
 
 8 
 
 6 
 
 55 
 
 56 
 
 35 
 
 33 
 
 30 
 
 28 
 
 25 
 
 23 
 
 21 
 
 19 
 
 16 
 
 14 
 
 12 
 
 10 
 
 8 
 
 56 
 
 57 
 
 36 
 
 34 
 
 32 
 
 29 
 
 27 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 13 
 
 11 
 
 9 
 
 57 
 
 58 
 
 37 
 
 35 
 
 33 
 
 30 
 
 28 
 
 26 
 
 24 
 
 21 
 
 19 
 
 17 
 
 15 
 
 13 
 
 11 
 
 58 
 
 59 
 
 38 
 
 36 
 
 34 
 
 31 
 
 29 
 
 27 
 
 25 
 
 23 
 
 21 
 
 18 
 
 16 
 
 14 
 
 12 
 
 59 
 
 60 
 
 39 
 
 37 
 
 34 
 
 32 
 
 30 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 60 
 
 61 
 
 40 
 
 38 
 
 35 
 
 33 
 
 32 
 
 29 
 
 27 
 
 25 
 
 23 
 
 21 
 
 19 
 
 17 
 
 15 
 
 61 
 
 62 
 
 41 
 
 39 
 
 37 
 
 34 
 
 32 
 
 30 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 62 
 
 63 
 
 42 
 
 40 
 
 38 
 
 36 
 
 33 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 63 
 
 64 
 
 43 
 
 41 
 
 38 
 
 36 
 
 34 
 
 32 
 
 30 
 
 29 
 
 27 
 
 25 
 
 23 
 
 21 
 
 19 
 
 64 
 
 65 
 
 44 
 
 42 
 
 39 
 
 37 
 
 35 
 
 33 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 65 
 
 66 
 
 45 
 
 42 
 
 40 
 
 38 
 
 36 
 
 34 
 
 32 
 
 30 
 
 29 
 
 27 
 
 25 
 
 23 
 
 22 
 
 66 
 
 67 
 
 45 
 
 43 
 
 41 
 
 39 
 
 37 
 
 35 
 
 33 
 
 32 
 
 30 
 
 28 
 
 26 
 
 25 
 
 23 
 
 67 
 
 68 
 
 46 
 
 44 
 
 42 
 
 40 
 
 38 
 
 36 
 
 34 
 
 33 
 
 31 
 
 29 
 
 27 
 
 26 
 
 24 
 
 68 
 
 69 
 
 47 
 
 45 
 
 43 
 
 41 
 
 39 
 
 37 
 
 35 
 
 33 
 
 32 
 
 30 
 
 28 
 
 26 
 
 25 
 
 69 
 
 70 
 
 48 
 
 46 
 
 44 
 
 42 
 
 40 
 
 38 
 
 36 
 
 34 
 
 33 
 
 31 
 
 29 
 
 27 
 
 26 
 
 70 
 
 71 
 
 48 
 
 46 
 
 45 
 
 43 
 
 41 
 
 39 
 
 37 
 
 .35 
 
 34 
 
 32 
 
 30 
 
 28 
 
 27 
 
 71 
 
 72 
 
 49 
 
 47 
 
 45 
 
 43 
 
 42 
 
 40 
 
 38 
 
 36 
 
 35 
 
 33 
 
 31 
 
 30 
 
 28 
 
 72 
 
 73 
 
 50 
 
 48 
 
 46 
 
 44 
 
 42 
 
 41 
 
 39 
 
 37 
 
 35 
 
 34 
 
 32 
 
 30 
 
 29 
 
 73 
 
 74 
 
 50 
 
 48 
 
 47 
 
 45 
 
 43 
 
 41 
 
 40 
 
 38 
 
 36 
 
 35 
 
 33 
 
 31 
 
 30 
 
 74 
 
 75 
 
 51 
 
 49 
 
 47 
 
 46 
 
 44 
 
 42 
 
 40 
 
 39 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 75 
 
 76 
 
 52 
 
 50 
 
 48 
 
 46 
 
 45 
 
 43 
 
 41 
 
 39 
 
 38 
 
 36 
 
 35 
 
 33 
 
 31 
 
 76 
 
 77 
 
 52 
 
 50 
 
 49 
 
 47 
 
 45 
 
 44 
 
 42 
 
 40 
 
 39 
 
 37 
 
 35 
 
 34 
 
 32 
 
 77 
 
 78 
 
 53 
 
 51 
 
 49 
 
 48 
 
 46 
 
 44 
 
 43 
 
 41 
 
 39 
 
 38 
 
 36 
 
 35 
 
 33 
 
 78 
 
 79 
 
 53 
 
 52 
 
 50 
 
 48 
 
 47 
 
 45 
 
 43 
 
 42 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 79 
 
 80 
 
 54 
 
 52 
 
 51 
 
 49 
 
 47 
 
 45 
 
 44 
 
 42 
 
 41 
 
 39 
 
 38 
 
 36 
 
 35 
 
 80 
 
 fc 
 
 12. 
 
 12. 5 
 
 13. 
 
 13. 5 
 
 14. 
 
 14. 5 
 
 15. 
 
 15. 5 
 
 16. 
 
 16. 5 
 
 17. 
 
 17. 5 
 
 18. 
 
 t. 
 
TABLE II. Relative humidity, per cent. 
 
 ? 
 
 Difference between the dry and wet thermometers (1 <'). 
 
 y 
 
 2 
 
 1 
 
 18.0 
 
 19.0 
 
 20.0 
 
 21.0 
 
 22. 
 
 23.0 
 
 24.0 
 
 25.0 
 
 26.0 
 
 27.0 
 
 28.0 
 
 29.(> 
 
 30.0 
 
 *j& 
 
 , 
 
 55 
 
 6 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 55 
 
 50 
 
 8 
 
 3 
 
 
 
 
 
 
 
 
 
 
 
 
 56 
 
 57 
 
 9 
 
 5 
 
 
 
 
 
 
 
 
 
 
 
 
 57 
 
 58 
 
 11 
 
 7 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 58 
 
 59 
 
 12 
 
 8 
 
 4 
 
 
 
 
 
 
 
 
 
 
 
 59 
 
 60 
 
 14 
 
 10 
 
 6 
 
 2 
 
 
 
 
 
 
 
 
 
 
 60 
 
 61 
 
 15 
 
 11 
 
 7 
 
 3 
 
 
 
 
 
 
 
 
 
 
 61 
 
 62 
 
 16 
 
 13 
 
 9 
 
 5 
 
 1 
 
 
 
 
 
 
 
 
 
 62 
 
 63 
 
 18 
 
 14 
 
 10 
 
 7 
 
 3 
 
 
 
 
 
 
 
 
 
 63 
 
 64 
 
 19 
 
 15 
 
 12 
 
 8 
 
 5 
 
 1 
 
 
 
 
 
 
 
 
 64 
 
 65 
 
 20 
 
 17 
 
 13 
 
 10 
 
 6 
 
 3 
 
 
 
 
 
 
 
 
 65 
 
 66 
 
 22 
 
 18 
 
 14 
 
 11 
 
 8 
 
 4 
 
 1 
 
 
 
 
 
 
 
 66 
 
 67 
 
 23 
 
 19 
 
 16 
 
 12 
 
 9 
 
 6 
 
 2 
 
 
 
 
 
 
 
 67 
 
 68 
 
 24 
 
 20 
 
 17 
 
 14 
 
 10 
 
 7 
 
 4 
 
 1 
 
 
 
 
 
 
 68 
 
 69 
 
 25 
 
 22 
 
 18 
 
 15 
 
 12 
 
 8 
 
 5 
 
 2 
 
 
 
 
 
 
 69 
 
 70 
 
 26 
 
 23 
 
 19 
 
 16 
 
 13 
 
 10 
 
 7 
 
 4 
 
 1 
 
 
 
 
 
 70 
 
 71 
 
 27 
 
 24 
 
 20 
 
 17 
 
 14 
 
 11 
 
 8 
 
 5 
 
 2 
 
 
 
 
 
 71 
 
 72 
 
 28 
 
 24 
 
 22 
 
 18 
 
 15 
 
 12 
 
 9 
 
 6 
 
 3 
 
 1 
 
 
 
 
 72 
 
 73 
 
 29 
 
 25 
 
 22 
 
 19 
 
 16 
 
 13 
 
 10 
 
 8 
 
 5 
 
 2 
 
 
 
 
 73 
 
 74 
 
 30 
 
 26 
 
 23 
 
 20 
 
 18 
 
 15 
 
 12 
 
 9 
 
 6 
 
 3 
 
 1 
 
 
 
 74 
 
 75 
 
 31 
 
 27 
 
 24 
 
 21 
 
 19 
 
 16 
 
 13 
 
 10 
 
 7 
 
 5 
 
 2 
 
 
 
 75 
 
 76 
 
 31 
 
 28 
 
 25 
 
 22 
 
 20 
 
 17 
 
 14 
 
 11 
 
 8 
 
 6 
 
 3 
 
 1 
 
 
 76 
 
 77 
 
 32 
 
 29 
 
 26 
 
 23 
 
 20 
 
 18 
 
 15 
 
 12 
 
 10 
 
 7 
 
 4 
 
 2 
 
 
 77 
 
 78 
 
 33 
 
 30 
 
 27 
 
 24 
 
 21 
 
 19 
 
 16 
 
 13 
 
 11 
 
 8 
 
 6 
 
 3 
 
 1 
 
 78 
 
 79 
 
 34 
 
 31 
 
 28 
 
 25 
 
 22 
 
 19 
 
 17 
 
 14 
 
 12 
 
 9 
 
 7 
 
 4 
 
 2 
 
 79 
 
 80 
 
 35 
 
 32 
 
 29 
 
 26 
 
 23 
 
 20 
 
 18 
 
 15 
 
 13 
 
 10 
 
 8 
 
 6 
 
 3 
 
 80 
 
 t. 
 
 18.0 
 
 19.0 
 
 20.0 
 
 21.0 
 
 22. 
 
 23. 
 
 24. 
 
 25. 
 
 26. 
 
 27.0 
 
 28.0 
 
 29.0 
 
 303.0 
 
 t. 
 
87 
 
 TABLE II. Relative humidity, per cent. 
 
 0) 
 
 Difference between the dry and wet thermometers (t t'). 
 
 1 
 
 ft 
 
 10.0 
 
 2 J .0 
 
 3.0 
 
 4.0 
 
 5.0 
 
 6.0 
 
 7.0 
 
 8.0 
 
 9.0 
 
 10.0 
 
 mo 
 
 12.0 
 
 "1 
 
 80 
 
 96 
 
 92 
 
 87 
 
 83 
 
 79 
 
 75 
 
 72 
 
 68 
 
 64 
 
 61 
 
 57 
 
 54 
 
 80 
 
 81 
 
 96 
 
 92 
 
 88 
 
 84 
 
 80 
 
 76 
 
 72 
 
 68 
 
 65 
 
 61 
 
 58 
 
 54 
 
 81 
 
 82 
 
 96 
 
 92 
 
 88 
 
 84 
 
 80 
 
 76 
 
 72 
 
 69 
 
 65 
 
 62 
 
 58 
 
 55 
 
 82 
 
 83 
 
 96 
 
 92 
 
 88 
 
 84 
 
 80 
 
 76 
 
 73 
 
 69 
 
 66 
 
 62 
 
 59 
 
 55 
 
 83 
 
 84 
 
 96 
 
 92 
 
 88 
 
 84 
 
 80 
 
 77 
 
 73 
 
 69 
 
 66 
 
 63 
 
 59 
 
 56 
 
 84 
 
 85 
 
 96 
 
 92 
 
 88 
 
 84 
 
 80 
 
 77 
 
 73 
 
 70 
 
 66 
 
 63 
 
 60 
 
 56 
 
 85 
 
 86 
 
 96 
 
 92 
 
 88 
 
 84 
 
 81 
 
 77 
 
 73 
 
 70 
 
 67 
 
 63 
 
 60 
 
 57 
 
 86 
 
 87 
 
 96 
 
 92 
 
 88 
 
 84 
 
 81 
 
 77 
 
 74 
 
 70 
 
 67 
 
 64 
 
 60 
 
 57 
 
 87 
 
 88 
 
 96 
 
 92 
 
 88 
 
 85 
 
 81 
 
 77 
 
 74 
 
 71 
 
 67 
 
 64 
 
 61 
 
 58 
 
 88 
 
 89 
 
 96 
 
 92 
 
 88 
 
 85 
 
 81 
 
 78 
 
 74 
 
 71 
 
 68 
 
 64 
 
 61 
 
 58 
 
 89 
 
 90 
 
 96 
 
 92 
 
 88 
 
 85 
 
 81 
 
 78 
 
 75 
 
 71 
 
 68 
 
 65 
 
 62 
 
 59 
 
 90 
 
 91 
 
 96 
 
 92 
 
 89 
 
 85 
 
 82 
 
 78 
 
 75 
 
 71 
 
 68 
 
 65 
 
 62 
 
 59 
 
 91 
 
 92 
 
 96 
 
 92 
 
 89 
 
 85 
 
 82 
 
 78 
 
 75 
 
 72 
 
 69 
 
 65 
 
 62 
 
 59 
 
 92 
 
 93 
 
 96 
 
 93 
 
 89 
 
 85 
 
 82 
 
 78 
 
 75 
 
 72 
 
 69 
 
 66 
 
 63 
 
 60 
 
 93 
 
 94 
 
 96 
 
 93 
 
 89 
 
 86 
 
 82 
 
 79 
 
 75 
 
 72 
 
 69 
 
 66 
 
 63 
 
 60 
 
 94 
 
 95 
 
 96 
 
 93 
 
 89 
 
 86 
 
 82 
 
 79 
 
 76 
 
 72 
 
 69 
 
 66 
 
 63 
 
 60 
 
 95 
 
 96 
 
 96 
 
 93 
 
 89 
 
 86 
 
 82 
 
 79 
 
 76 
 
 73 
 
 70 
 
 67 
 
 64 
 
 61 
 
 96 
 
 97 
 
 96 
 
 93 
 
 89 
 
 86 
 
 82 
 
 79 
 
 76 
 
 73 
 
 70 
 
 67 
 
 64 
 
 61 
 
 97 
 
 98 
 
 96 
 
 93 
 
 89 
 
 86 
 
 83 
 
 79 
 
 76 
 
 73 
 
 70 
 
 67 
 
 64 
 
 61 
 
 98 
 
 99 
 
 96 
 
 93 
 
 89 
 
 86 
 
 83 
 
 80 
 
 76 
 
 73 
 
 70 
 
 68 
 
 65 
 
 62 
 
 99 
 
 100 
 
 97 
 
 93 
 
 90 
 
 86 
 
 83 
 
 80 
 
 77 
 
 74 
 
 71 
 
 68 
 
 65 
 
 62 
 
 100 
 
 101 
 
 97 
 
 93 
 
 90 
 
 86 
 
 83 
 
 80 
 
 77 
 
 74 
 
 71 
 
 68 
 
 65 
 
 62 
 
 101 
 
 102 
 
 97 
 
 93 
 
 90 
 
 86 
 
 83 
 
 80 
 
 77 
 
 74 
 
 71 
 
 68 
 
 65 
 
 63 
 
 102 
 
 103 
 
 97 
 
 93 
 
 90 
 
 87 
 
 83 
 
 80 
 
 77 
 
 74 
 
 71 
 
 69 
 
 66 
 
 63 
 
 103 
 
 104 
 
 97 
 
 93 
 
 90 
 
 87 
 
 83 
 
 80 
 
 77 
 
 74 
 
 72 
 
 69 
 
 66 
 
 63 
 
 104 
 
 105 
 
 97 
 
 93 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 75 
 
 72 
 
 69 
 
 66 
 
 64 
 
 105 
 
 106 
 
 97 
 
 93 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 75 
 
 72 
 
 69 
 
 66 
 
 64 
 
 106 
 
 107 
 
 97 
 
 93 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 75 
 
 72 
 
 69 
 
 67 
 
 64 
 
 107 
 
 108 
 
 97 
 
 93 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 75 
 
 72 
 
 70 
 
 67 
 
 64 
 
 108 
 
 109 
 
 97 
 
 93 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 75 
 
 73 
 
 70 
 
 67 
 
 65 
 
 109 
 
 110 
 
 97 
 
 94 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 76 
 
 73 
 
 70 
 
 67 
 
 65 
 
 110 
 
 111 
 
 97 
 
 94 
 
 90 
 
 87 
 
 84 
 
 81 
 
 78 
 
 76 
 
 73 
 
 70 
 
 68 
 
 65 
 
 111 
 
 112 
 
 97 
 
 94 
 
 90 
 
 87 
 
 84 
 
 82 
 
 79 
 
 76 
 
 73 
 
 71 
 
 68 
 
 65 
 
 112 
 
 113 
 
 97 
 
 94 
 
 90 
 
 87 
 
 85 
 
 82 
 
 79 
 
 76 
 
 73 
 
 71 
 
 68 
 
 66 
 
 113 
 
 114 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 79 
 
 76 
 
 74 
 
 71 
 
 68 
 
 66 
 
 114 
 
 115 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 79 
 
 76 
 
 74 
 
 71 
 
 69 
 
 66 
 
 115 
 
 116 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 79 
 
 76 
 
 74 
 
 71 
 
 69 
 
 66 
 
 116 
 
 117 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 79 
 
 77 
 
 74 
 
 71 
 
 69 
 
 66 
 
 117 
 
 118 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 79 
 
 77 
 
 74 
 
 72 
 
 69 
 
 67 
 
 118 
 
 119 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 82 
 
 80 
 
 77 
 
 74 
 
 72 
 
 69 
 
 67 
 
 119 
 
 120 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 83 
 
 80 
 
 77 
 
 75 
 
 72 
 
 70 
 
 67 
 
 120 
 
 121 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 83 
 
 80 
 
 77 
 
 75 
 
 72 
 
 70 
 
 67 
 
 121 
 
 122 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 83 
 
 80 
 
 77 
 
 75 
 
 72 
 
 70 
 
 67 
 
 122 
 
 123 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 83 
 
 80 
 
 78 
 
 75 
 
 73 
 
 70 
 
 68 
 
 123 
 
 124 
 
 97 
 
 94 
 
 91 
 
 88 
 
 85 
 
 83 
 
 80 
 
 78 
 
 75 
 
 73 
 
 70 
 
 68 
 
 124 
 
 125 
 
 97 
 
 94 
 
 91 
 
 88 
 
 86 
 
 83 
 
 80 
 
 78 
 
 75 
 
 73 
 
 70 
 
 68 
 
 125 
 
 126 
 
 97 
 
 94 
 
 91 
 
 88 
 
 86 
 
 83 
 
 80 
 
 78 
 
 75 
 
 73 
 
 71 
 
 68 
 
 126 
 
 127 
 
 97 
 
 94 
 
 91 
 
 89 
 
 86 
 
 83 
 
 81 
 
 78 
 
 76 
 
 73 
 
 71 
 
 68 
 
 127 
 
 128 
 
 97 
 
 94 
 
 91 
 
 89 
 
 86 
 
 83 
 
 81 
 
 78 
 
 76 
 
 73 
 
 71 
 
 68 
 
 128 
 
 1*9 
 
 97 
 
 94 
 
 91 
 
 89 
 
 86 
 
 83 
 
 81 
 
 78 
 
 76 
 
 73 
 
 71 
 
 69 
 
 129 
 
 130 
 
 97 
 
 94 
 
 91 
 
 89 
 
 86 
 
 83 
 
 81 
 
 78 
 
 76 
 
 74 
 
 71 
 
 69 
 
 130 
 
 131 
 
 97 
 
 94 
 
 92 
 
 89 
 
 86 
 
 84 
 
 81 
 
 79 
 
 76 
 
 74 
 
 71 
 
 69 
 
 131 
 
 132 
 
 97 
 
 94 
 
 92 
 
 89 
 
 86 
 
 84 
 
 81 
 
 79 
 
 76 
 
 74 
 
 72 
 
 69 
 
 132 
 
 133 
 
 97 
 
 94 
 
 92 
 
 89 
 
 86 
 
 84 
 
 81 
 
 79 
 
 76 
 
 ' 74 
 
 72 
 
 69 
 
 133 
 
 134 
 
 97 
 
 94 
 
 92 
 
 89 
 
 86 
 
 84 
 
 81 
 
 79 
 
 76 
 
 74 
 
 72 
 
 70 
 
 134 
 
 135 
 
 97 
 
 94 
 
 92 
 
 89 
 
 86 
 
 84 
 
 81 
 
 79 
 
 77 
 
 74 
 
 72 
 
 70 
 
 135 
 
 136 
 
 97 
 
 94 
 
 92 
 
 89 
 
 87 
 
 84 
 
 82 
 
 79 
 
 77 
 
 74 
 
 72 
 
 70 
 
 136 
 
 137 
 
 97 
 
 94 
 
 92 
 
 89 
 
 87 
 
 84 
 
 82 
 
 79 
 
 77 
 
 74 
 
 72 
 
 70 
 
 137 
 
 138 
 
 97 
 
 95 
 
 92 
 
 89 
 
 87 
 
 84 
 
 82 
 
 79 
 
 77 
 
 74 
 
 73 
 
 70 
 
 138 
 
 139 
 
 97 
 
 95 
 
 92 
 
 89 
 
 87 
 
 84 
 
 82 
 
 79 
 
 77 
 
 75 
 
 73 
 
 70 
 
 139 
 
 140 
 
 97 
 
 95 
 
 92 
 
 89 
 
 87 
 
 84 
 
 82 
 
 79 
 
 77 
 
 75 
 
 73 
 
 71 
 
 140 
 
 t. 
 
 1... 
 
 2.0 
 
 3.0 
 
 4.0 
 
 5.0 
 
 6.0 
 
 7.0 
 
 8.0 
 
 9.0 
 
 10.0 
 
 mo 
 
 12.0 
 
 t. 
 
88 
 
 TABLE II. Eelative humidity, per cent. 
 
 ? 
 
 Difference between the dry and wet thermometers ( t tf). 
 
 ? 
 
 
 
 
 J9 
 
 - +- 
 
 ~I 
 
 12.0 
 
 13.0 
 
 14.0 
 
 15.0 
 
 16.0 
 
 17.0 
 
 18.0 
 
 19.0 
 
 20. 
 
 21.0 
 
 22.0 
 
 23.0 
 
 24.0 
 
 | 
 
 80 
 
 54 
 
 51 
 
 47 
 
 44 
 
 41 
 
 38 
 
 35 
 
 32 
 
 29 
 
 26 
 
 23 
 
 20 
 
 18 
 
 80 
 
 81 
 
 54 
 
 51 
 
 48 
 
 44 
 
 41 
 
 38 
 
 35 
 
 33 
 
 30 
 
 27 
 
 24 
 
 21 
 
 19 
 
 81 
 
 82 
 
 55 
 
 52 
 
 48 
 
 45 
 
 42 
 
 39 
 
 36 
 
 33 
 
 31 
 
 28 
 
 25 
 
 22 
 
 20 
 
 82 
 
 83 
 
 55 
 
 52 
 
 49 
 
 46 
 
 43 
 
 40 
 
 37 
 
 34 
 
 31 
 
 29 
 
 26 
 
 23 
 
 21 
 
 83 
 
 84 
 
 56 
 
 53 
 
 49 
 
 4G 
 
 44 
 
 41 
 
 38 
 
 35 
 
 32 
 
 29 
 
 27 
 
 24 
 
 22 
 
 84 
 
 85 
 
 56 
 
 53 
 
 50 
 
 47 
 
 44 
 
 41 
 
 38 
 
 36 
 
 33 
 
 30 
 
 28 
 
 25 
 
 22 
 
 85 
 
 86 
 
 57 
 
 54 
 
 51- 
 
 48 
 
 45 
 
 42 
 
 39 
 
 36 
 
 34 
 
 31 
 
 29 
 
 26 
 
 23 
 
 86 
 
 87 
 
 57 
 
 54 
 
 51 
 
 48 
 
 45 
 
 42 
 
 40 
 
 37 
 
 34 
 
 32 
 
 30 
 
 27 
 
 24 
 
 87 
 
 88 
 
 58 
 
 55 
 
 52 
 
 49 
 
 46 
 
 43 
 
 40 
 
 38 
 
 35 
 
 32 
 
 30 
 
 27 
 
 25 
 
 88 
 
 89 
 
 58 
 
 55 
 
 52 
 
 49 
 
 46 
 
 44 
 
 41 
 
 38 
 
 36 
 
 33 
 
 31 
 
 28 
 
 26 
 
 89 
 
 90 
 
 59 
 
 56 
 
 53 
 
 50 
 
 47 
 
 44 
 
 41 
 
 39 
 
 36 
 
 34 
 
 32 
 
 29 
 
 26 
 
 90 
 
 91 
 
 59 
 
 56 
 
 53 
 
 50 
 
 47 
 
 45 
 
 42 
 
 39 
 
 37 
 
 35 
 
 33 
 
 30 
 
 27 
 
 91 
 
 92 
 
 59 
 
 56 
 
 54 
 
 51 
 
 48 
 
 45 
 
 43 
 
 40 
 
 37 
 
 35 
 
 33 
 
 30 
 
 28 
 
 92 
 
 93 
 
 60 
 
 57 
 
 54 
 
 51 
 
 48 
 
 46 
 
 43 
 
 41 
 
 38 
 
 36 
 
 34 
 
 31 
 
 29 
 
 93 
 
 94 
 
 60 
 
 57 
 
 54 
 
 52 
 
 49 
 
 46 
 
 44 
 
 41 
 
 39 
 
 36 
 
 34 
 
 31 
 
 29 
 
 94 
 
 95 
 
 60 
 
 58 
 
 55 
 
 52 
 
 49 
 
 47 
 
 44 
 
 42 
 
 39 
 
 37 
 
 35 
 
 32 
 
 30 
 
 95 
 
 96 
 
 61 
 
 58 
 
 55 
 
 53 
 
 50 
 
 47 
 
 45 
 
 42 
 
 40 
 
 37 
 
 36 
 
 33 
 
 30 
 
 96 
 
 97 
 
 61 
 
 58 
 
 56 
 
 53 
 
 50 
 
 48 
 
 45 
 
 43 
 
 40 
 
 38 
 
 36 
 
 33 
 
 31 
 
 97 
 
 98 
 
 61 
 
 59 
 
 56 
 
 53 
 
 51 
 
 48 
 
 46 
 
 43 
 
 41 
 
 38 
 
 37 
 
 34 
 
 32 
 
 *98 
 
 99 
 
 62 
 
 59 
 
 56 
 
 54 
 
 51 
 
 49 
 
 46 
 
 44 
 
 41 
 
 39 
 
 37 
 
 34 
 
 32 
 
 99 
 
 100 
 
 62 
 
 59 
 
 57 
 
 54 
 
 51 
 
 49 
 
 47 
 
 44 
 
 42 
 
 39 
 
 37 
 
 35 
 
 33 
 
 100 
 
 101 
 
 62 
 
 60 
 
 57 
 
 54 
 
 52 
 
 49 
 
 47 
 
 45 
 
 42 
 
 40 
 
 38 
 
 36 
 
 33 
 
 101 
 
 102 
 
 63 
 
 60 
 
 57 
 
 55 
 
 52 
 
 50 
 
 47 
 
 45 
 
 43 
 
 40 
 
 38 
 
 36 
 
 34 
 
 102 
 
 103 
 
 63 
 
 60 
 
 58 
 
 55 
 
 53 
 
 50 
 
 48 
 
 45 
 
 43 
 
 41 
 
 39 
 
 37 
 
 34 
 
 103 
 
 104 
 
 63 
 
 61 
 
 58 
 
 55 
 
 53 
 
 51 
 
 48 
 
 46 
 
 44 
 
 41 
 
 39 
 
 37 
 
 35 
 
 104 
 
 105 
 
 64 
 
 61 
 
 58 
 
 56 
 
 53 
 
 51 
 
 49 
 
 46 
 
 44 
 
 42 
 
 40 
 
 38 
 
 35 
 
 105 
 
 106 
 
 64 
 
 61 
 
 59 
 
 56 
 
 54 
 
 51 
 
 49 
 
 47 
 
 44 
 
 42 
 
 40 
 
 38 
 
 36 
 
 106 
 
 107 
 
 64 
 
 62 
 
 59 
 
 57 
 
 54 
 
 52 
 
 49 
 
 47 
 
 45 
 
 43 
 
 41 
 
 38 
 
 36 
 
 107 
 
 108 
 
 64 
 
 62 
 
 59 
 
 57 
 
 64 
 
 52 
 
 50 
 
 47 
 
 45 
 
 43 
 
 41 
 
 39 
 
 37 
 
 108 
 
 109 
 
 65 
 
 62 
 
 60 
 
 57 
 
 55 
 
 52 
 
 50 
 
 48 
 
 46 
 
 44 
 
 41 
 
 39 
 
 37 
 
 109 
 
 110 
 
 65 
 
 62 
 
 60 
 
 57 
 
 55 
 
 53 
 
 50 
 
 48 
 
 46 
 
 44 
 
 42 
 
 40 
 
 38 
 
 110 
 
 111 
 
 65 
 
 63 
 
 60 
 
 58 
 
 55 
 
 53 
 
 51 
 
 49 
 
 46 
 
 44 
 
 42 
 
 40 
 
 38 
 
 111 
 
 112 
 
 65 
 
 63 
 
 60 
 
 58 
 
 56 
 
 53 
 
 51 
 
 49 
 
 47 
 
 45 
 
 43 
 
 40 
 
 39 
 
 112 
 
 113 
 
 66 
 
 63 
 
 61 
 
 58 
 
 56 
 
 54 
 
 51 
 
 49 
 
 47 
 
 45 
 
 43 
 
 41 
 
 39 
 
 113 
 
 114 
 
 66 
 
 63 
 
 61 
 
 59 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 45 
 
 44 
 
 41 
 
 39 
 
 114 
 
 115 
 
 66 
 
 64 
 
 61 
 
 59 
 
 57 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 44 
 
 42 
 
 40 
 
 115 
 
 116 
 
 66 
 
 64 
 
 61 
 
 59 
 
 57 
 
 55 
 
 52 
 
 50 
 
 48 
 
 46 
 
 44 
 
 42 
 
 40 
 
 116 
 
 117 
 
 66 
 
 64 
 
 62 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 46 
 
 44 
 
 43 
 
 41 
 
 117 
 
 118 
 
 67 
 
 .64 
 
 62 
 
 60 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 45 
 
 43 
 
 41 
 
 118 
 
 119 
 
 67 
 
 64 
 
 62 
 
 60 
 
 58 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 45 
 
 43 
 
 41 
 
 119 
 
 120 
 
 67 
 
 65 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 51 
 
 49 
 
 47 
 
 45 
 
 44 
 
 42 
 
 120 
 
 121 
 
 67 
 
 65 
 
 63 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 44 
 
 42 
 
 121 
 
 122 
 
 67 
 
 65 
 
 63 
 
 61 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 44 
 
 42 
 
 122 
 
 123 
 
 68 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 45 
 
 43 
 
 123 
 
 124 
 
 68 
 
 66 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 45 
 
 43 
 
 124 
 
 125 
 
 68 
 
 66 
 
 64 
 
 62 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 45 
 
 43 
 
 125 
 
 126 
 
 68 
 
 66 
 
 64 
 
 62 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 46 
 
 44 
 
 126 
 
 127 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 55 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 44 
 
 127 
 
 128 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 44 
 
 128 
 
 129 
 
 69 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 46 
 
 45 
 
 129 
 
 130 
 
 69 
 
 67 
 
 65 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 49 
 
 47 
 
 45 
 
 130 
 
 131 
 
 69 
 
 67 
 
 65 
 
 63 
 
 60 
 
 58 
 
 56 
 
 54 
 
 53 
 
 51 
 
 49. 
 
 47 
 
 45 
 
 131 
 
 132 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 47 
 
 46 
 
 132 
 
 133 
 
 69 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 49 
 
 48 
 
 46 
 
 133 
 
 134 
 
 70 
 
 67 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 50 
 
 48 
 
 46 
 
 134 
 
 135 
 
 70 
 
 68 
 
 65 
 
 63 
 
 61 
 
 59 
 
 57 
 
 55 
 
 53 
 
 51 
 
 50 
 
 48 
 
 46 
 
 135 
 
 136 
 
 70 
 
 68 
 
 66 
 
 64 
 
 61 
 
 59 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 48 
 
 47 
 
 136 
 
 137 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 50 
 
 49 
 
 47 
 
 137 
 
 138 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 52 
 
 51 
 
 49 
 
 47 
 
 138 
 
 139 
 
 70 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 54 
 
 53 
 
 51 
 
 49 
 
 47 
 
 139 
 
 140 
 
 71 
 
 68 
 
 66 
 
 64 
 
 62 
 
 60 
 
 58 
 
 56 
 
 55 
 
 53 
 
 51 
 
 49 
 
 48 
 
 140 
 
 t. 
 
 12.0 
 
 13.0 
 
 14.0 
 
 15.0 
 
 16.0 
 
 17.0 
 
 18.0 
 
 19.0 
 
 20.0 
 
 21.0 
 
 22.0 
 
 23.0 
 
 24.0 
 
 t. 
 
89 
 
 TABLE II. Relative humidity, per cent. 
 
 .1 
 
 Difference between the dry and wet thermometers (t if). 
 
 I 
 
 
 4.0 
 
 25.0 
 
 26.0 
 
 27.0 
 
 8.0 
 
 29.0 
 
 30.0 
 
 31.0 
 
 32.0 
 
 33.0 
 
 34.0 
 
 35.0 
 
 36.0 
 
 ~| 
 
 80 
 
 18 
 
 15 
 
 13 
 
 10 
 
 8 
 
 6 
 
 3 
 
 1 
 
 
 
 
 
 
 80 
 
 81 
 
 19 
 
 16 
 
 14 
 
 11 
 
 9 
 
 7 
 
 4 
 
 2 
 
 
 
 
 
 
 81 
 
 82 
 
 20 
 
 17 
 
 15 
 
 12 
 
 10 
 
 8 
 
 5 
 
 3 
 
 1 
 
 
 
 
 
 82 
 
 83 
 
 21 
 
 18 
 
 16 
 
 13 
 
 11 
 
 9 
 
 6 
 
 4 
 
 2 
 
 
 
 
 
 83 
 
 84 
 
 22 
 
 19 
 
 17 
 
 14 
 
 12 
 
 10 
 
 8 
 
 5 
 
 3 
 
 1 
 
 
 
 
 84 
 
 85 
 
 22 
 
 20 
 
 17 
 
 15 
 
 13 
 
 11 
 
 9 
 
 6 
 
 4 
 
 2 
 
 
 
 
 85 
 
 86 
 
 23 
 
 21 
 
 18 
 
 16 
 
 14 
 
 12 
 
 10 
 
 7 
 
 5 
 
 3 
 
 1 
 
 
 
 86 
 
 87 
 
 24 
 
 22 
 
 19 
 
 17 
 
 15 
 
 13 
 
 11 
 
 8 
 
 6 
 
 4 
 
 2 
 
 
 
 87 
 
 88 
 
 25 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 12 
 
 9 
 
 7 
 
 5 
 
 3 
 
 1 
 
 
 88 
 
 89 
 
 26 
 
 23 
 
 21 
 
 19 
 
 16 
 
 14 
 
 12 
 
 10 
 
 8 
 
 6 
 
 4 
 
 2 
 
 1 
 
 89 
 
 90 
 
 26 
 
 24 
 
 22 
 
 20 
 
 17 
 
 15 
 
 13 
 
 11 
 
 9 
 
 7 
 
 5 
 
 3 
 
 2 
 
 90 
 
 91 
 
 27 
 
 25 
 
 23 
 
 20 
 
 18 
 
 16 
 
 14 
 
 12 
 
 10 
 
 8- 
 
 6 
 
 4 
 
 3 
 
 91 
 
 92 
 
 28 
 
 26 
 
 23 
 
 21 
 
 19 
 
 17 
 
 15 
 
 13 
 
 11 
 
 9 
 
 7 
 
 5 
 
 3 
 
 92 
 
 93 
 
 29 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 12 
 
 10 
 
 8 
 
 6 
 
 4 
 
 93 
 
 94 
 
 29 
 
 27 
 
 25 
 
 23 
 
 21 
 
 18 
 
 16 
 
 14 
 
 13 
 
 11 
 
 9 
 
 7 
 
 5 
 
 94 
 
 95 
 
 30 
 
 28 
 
 25 
 
 23 
 
 21 
 
 19 
 
 17 
 
 15 
 
 13 
 
 11 
 
 10 
 
 8 
 
 6 
 
 95 
 
 96 
 
 30 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 14 
 
 12 
 
 10 
 
 9 
 
 7 
 
 96 
 
 97 
 
 31 
 
 29 
 
 27 
 
 25 
 
 23 
 
 21 
 
 19 
 
 17 
 
 15 
 
 13 
 
 11 
 
 10 
 
 8 
 
 97 
 
 98 
 
 32 
 
 29 
 
 27 
 
 25 
 
 23 
 
 21 
 
 19 
 
 18 
 
 16 
 
 14 
 
 12 
 
 10 
 
 9 
 
 98 
 
 99 
 
 32 
 
 30 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 18 
 
 16 
 
 15 
 
 13 
 
 11 
 
 10 
 
 99 
 
 100 
 
 33 
 
 31 
 
 29 
 
 27 
 
 25 
 
 23 
 
 21 
 
 19 
 
 17 
 
 15 
 
 14 
 
 12 
 
 10 
 
 100 
 
 101 
 
 33 
 
 31 
 
 29 
 
 27 
 
 25 
 
 23 
 
 21 
 
 20 
 
 18 
 
 16 
 
 14 
 
 13 
 
 11 
 
 101 
 
 102 
 
 34 
 
 32 
 
 30 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 19 
 
 17 
 
 15 
 
 13 
 
 12 
 
 102 
 
 103 
 
 34 
 
 32 
 
 30 
 
 28 
 
 26 
 
 25 
 
 23 
 
 21 
 
 19 
 
 17 
 
 16 
 
 14 
 
 12 
 
 103 
 
 104 
 
 35 
 
 33 
 
 31 
 
 29 
 
 27 
 
 25 
 
 23 
 
 22 
 
 20 
 
 18 
 
 16 
 
 15 
 
 13 
 
 104 
 
 105 
 
 35 
 
 33 
 
 31 
 
 30 
 
 28 
 
 26 
 
 24 
 
 22 
 
 20 
 
 19 
 
 17 
 
 15 
 
 14 
 
 105 
 
 106 
 
 36 
 
 34 
 
 32 
 
 30 
 
 28 
 
 26 
 
 25 
 
 23 
 
 21 
 
 19 
 
 18 
 
 16 
 
 14 
 
 106 
 
 107 
 
 36 
 
 34 
 
 32 
 
 31 
 
 29 
 
 27 
 
 25 
 
 23 
 
 22 
 
 20 
 
 18 
 
 17 
 
 15 
 
 107 
 
 108 
 
 37 
 
 35 
 
 33 
 
 31 
 
 29 
 
 27 
 
 26 
 
 24 
 
 22 
 
 21 
 
 19 
 
 17 
 
 16 
 
 108 
 
 109 
 
 37 
 
 35 
 
 33 
 
 32 
 
 30 
 
 28 
 
 26 
 
 25 
 
 23 
 
 21 
 
 20 
 
 18 
 
 16 
 
 109 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 110 
 
 38 
 
 36 
 
 34 
 
 32 
 
 30 
 
 28 
 
 27 
 
 25 
 
 23 
 
 22 
 
 20 
 
 19 
 
 17 
 
 110 
 
 111 
 
 38 
 
 36 
 
 34 
 
 33 
 
 31 
 
 29 
 
 27 
 
 26 
 
 24 
 
 22 
 
 21 
 
 19 
 
 18 
 
 111 
 
 112 
 
 39 
 
 37 
 
 35 
 
 33 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 23 
 
 21 
 
 20 
 
 18 
 
 112 
 
 113 
 
 39 
 
 37 
 
 35 
 
 33 
 
 32 
 
 30 
 
 28 
 
 27 
 
 25 
 
 23 
 
 22 
 
 20 
 
 19 
 
 113 
 
 114 
 
 39 
 
 38 
 
 36 
 
 34 
 
 32 
 
 30 
 
 29 
 
 27 
 
 25 
 
 24 
 
 22 
 
 21 
 
 19 
 
 114 
 
 115 
 
 40 
 
 38 
 
 36 
 
 34 
 
 33 
 
 31 
 
 29 
 
 28 
 
 26 
 
 24 
 
 23 
 
 21 
 
 20 
 
 115 
 
 116 
 
 40 
 
 39 
 
 37 
 
 35 
 
 33 
 
 31 
 
 30 
 
 28 
 
 26 
 
 25 
 
 23 
 
 22 
 
 20 
 
 116 
 
 117 
 
 41 
 
 39 
 
 37 
 
 35 
 
 33 
 
 32 
 
 30 
 
 29 
 
 27 
 
 25 
 
 24 
 
 22 
 
 21 
 
 117 
 
 118 
 
 41 
 
 39 
 
 37 
 
 36 
 
 34 
 
 32 
 
 31 
 
 29 
 
 27 
 
 26 24 
 
 23 . 
 
 21 
 
 118 
 
 119 
 
 41 
 
 40 
 
 38 
 
 36 
 
 34 
 
 33 
 
 31 
 
 29 
 
 28 
 
 26 
 
 25 
 
 23 
 
 22 
 
 119 
 
 120 
 
 42 
 
 40 
 
 38 
 
 36 
 
 35 
 
 33 
 
 31 
 
 30 
 
 28 
 
 27 
 
 25 
 
 24 
 
 22 
 
 120 
 
 121 
 
 42 
 
 40 
 
 38 
 
 37 
 
 35 
 
 33 
 
 32 
 
 30 
 
 29 
 
 27 
 
 26 
 
 24 
 
 23 
 
 121 
 
 122 
 
 42 
 
 41 
 
 39 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 29 
 
 28 
 
 26 
 
 25 
 
 23 
 
 122 
 
 123 
 
 43 
 
 41 
 
 39 
 
 37 
 
 36 
 
 34 
 
 33 
 
 31 
 
 29 
 
 28 
 
 26 
 
 25 
 
 24 
 
 123 
 
 124 
 
 43 
 
 41 
 
 40 
 
 38 
 
 36 
 
 35 
 
 33 
 
 31 
 
 30 
 
 28 
 
 27 
 
 25 
 
 24 
 
 124 
 
 125 
 
 43 
 
 42 
 
 40 
 
 38 
 
 37 
 
 35 
 
 33 
 
 32 
 
 30 
 
 29 
 
 27 
 
 26 
 
 24 
 
 125 
 
 126 
 
 44 
 
 42- 
 
 40 
 
 39 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 29 
 
 28 
 
 . 26 
 
 25 
 
 126 
 
 127 
 
 44 
 
 42 
 
 41 
 
 39 
 
 37 
 
 36 
 
 34 
 
 32 
 
 31 
 
 30 
 
 28 
 
 27 
 
 25 
 
 127 
 
 128 
 
 44 
 
 43 
 
 41 
 
 39 
 
 38 
 
 36 
 
 34 
 
 33 
 
 31 
 
 30 
 
 29 
 
 27 
 
 26 
 
 128 
 
 129 
 
 45 
 
 43 
 
 41 
 
 40 
 
 38 
 
 36 
 
 35 
 
 33 
 
 32 
 
 30 
 
 29 
 
 28 
 
 26 
 
 129 
 
 130 
 
 45 
 
 43 
 
 42 
 
 40 
 
 38 
 
 37 
 
 35 
 
 33 
 
 32 
 
 31 
 
 29 
 
 28 
 
 27 
 
 130 
 
 131 
 
 45 
 
 44 
 
 42 
 
 40 
 
 39 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 30 
 
 28 
 
 27 
 
 131 
 
 132 
 
 46 
 
 44 
 
 42 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 33 
 
 31 
 
 30 
 
 29 
 
 27 
 
 132 
 
 13' 
 
 46 
 
 44 
 
 42 
 
 41 
 
 39 
 
 38 
 
 36 
 
 35 
 
 33 
 
 32 
 
 30 
 
 29 
 
 28 
 
 133 
 
 134 
 
 46 
 
 44 
 
 43 
 
 41 
 
 39 
 
 38 
 
 36 
 
 35 
 
 33 
 
 32 
 
 31 
 
 29 
 
 28 
 
 134 
 
 135 
 
 46 
 
 45 
 
 43 
 
 41 
 
 40 
 
 38 
 
 37 
 
 35 
 
 34 
 
 32 
 
 31 
 
 30 
 
 28 
 
 135 
 
 136 
 
 47 
 
 45 
 
 43 
 
 42 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 33 
 
 31 
 
 30 
 
 29 
 
 136 
 
 13' 
 
 47 
 
 45 
 
 44 
 
 42 
 
 40 
 
 39 
 
 37 
 
 36 
 
 34 
 
 33 
 
 32 
 
 30 
 
 29 
 
 137 
 
 138 
 139 
 
 47 
 47 
 
 45 
 46 
 
 44 
 44 
 
 42 
 42 
 
 41 
 41 
 
 39 
 
 39 
 
 38 
 38 
 
 36 
 
 37 
 
 35 
 35 
 
 33 
 34 
 
 32 
 32 
 
 31 
 31 
 
 29 
 30 
 
 138 
 139 
 
 140 
 
 48 
 
 46 
 
 44 
 
 43 
 
 41 
 
 40 
 
 38 
 
 37 
 
 35 
 
 34 
 
 33 
 
 31 
 
 30 
 
 140 
 
 t. 
 
 24.0 
 
 25.0 
 
 26.0 
 
 27 c .O 
 
 28.0 
 
 29. 
 
 30. 
 
 31. 
 
 32.0 
 
 33.0 
 
 34. 
 
 35.0 
 
 36. 
 
 t. 
 
90 
 
 TABLE II. Relative humidity, per cent. 
 
 J 
 
 Difference between the dry and wet thermometers (t f). 
 
 J 
 
 b 
 
 e^ 
 
 36. 
 
 37. 
 
 38. 
 
 39. 
 
 40. 
 
 41. 
 
 42. 
 
 43. 
 
 44. 
 
 45. 
 
 46. 
 
 47. 
 
 48. 
 
 b 
 
 0, 
 
 89 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 
 89 
 
 90 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 
 
 90 
 
 91 
 
 3 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 
 91 
 
 92 
 
 3 
 
 2 
 
 1 
 
 
 
 
 
 
 
 
 
 
 
 92 
 
 93 
 
 4 
 
 3 
 
 2 
 
 
 
 
 
 
 
 
 
 
 
 93 
 
 94 
 
 5 
 
 4 
 
 8 
 
 
 
 
 
 
 
 
 
 
 
 
 94 
 
 95 
 
 6 
 
 5 
 
 4 
 
 1 
 
 
 
 
 
 
 
 
 
 
 95 
 
 96 
 
 7 
 
 5 
 
 5 
 
 2 
 
 1 
 
 
 
 
 
 
 
 
 
 96 
 
 97 
 
 8 
 
 6 
 
 6 
 
 3 
 
 1 
 
 
 
 
 
 
 
 
 
 97 
 
 98 
 
 9 
 
 7 
 
 7 
 
 4 
 
 2 
 
 1 
 
 
 
 
 
 
 
 
 98 
 
 99 
 
 10 
 
 8 
 
 7 
 
 5 
 
 3 
 
 2 
 
 
 
 
 
 
 
 
 
 99 
 
 100 
 
 10 
 
 9 ' 
 
 8 
 
 6 
 
 4 
 
 3 
 
 1 
 
 
 
 
 
 
 
 100 
 
 301 
 
 11 
 
 9 
 
 9 
 
 6 
 
 5 
 
 3 
 
 2 
 
 
 
 
 
 
 
 
 101 
 
 102 
 
 12 
 
 10 
 
 9 
 
 7 
 
 6 
 
 4 
 
 3 
 
 1 
 
 
 
 
 
 
 102 
 
 103 
 
 12 
 
 11 
 
 9 
 
 8 
 
 6 
 
 5 
 
 4 
 
 2 
 
 1 
 
 
 
 
 
 103 
 
 104 
 
 13 
 
 12 
 
 10 
 
 8 
 
 7 
 
 6 
 
 5 
 
 3 
 
 2 
 
 
 
 
 
 104 
 
 105 
 
 14 
 
 12 
 
 11 
 
 9 
 
 8 
 
 6 
 
 6 
 
 4 
 
 2 
 
 1 
 
 
 
 
 105 
 
 106 
 
 14 
 
 13 
 
 11 
 
 10 
 
 8 
 
 7 
 
 6 
 
 4 
 
 3 
 
 2 
 
 
 
 
 
 106 
 
 107 
 
 15 
 
 14 
 
 12 
 
 11 
 
 9 
 
 8 
 
 6 
 
 5 
 
 4 
 
 3 
 
 1 
 
 
 
 107 
 
 108 
 
 16 
 
 14 
 
 13 
 
 11 
 
 10 
 
 9 
 
 7 
 
 6 
 
 5 
 
 3 
 
 2 
 
 1 
 
 
 108 
 
 109 
 
 16 
 
 15 
 
 13 
 
 12 
 
 10 
 
 9 
 
 8 
 
 7 
 
 5 
 
 4 
 
 3 
 
 1 
 
 
 109 
 
 110 
 
 17 
 
 15 
 
 14 
 
 13 
 
 11 
 
 10 
 
 8 
 
 7 
 
 6 
 
 5 
 
 3 
 
 2 
 
 1 
 
 110 
 
 111 
 
 18 
 
 16 
 
 15 
 
 13 
 
 12 
 
 10 
 
 9 
 
 8 
 
 7 
 
 5 
 
 4 
 
 3 
 
 2 
 
 111 
 
 112 
 
 18 
 
 17 
 
 15 
 
 14 
 
 12 
 
 11 
 
 10 
 
 8 
 
 7 
 
 6 
 
 5 
 
 4 
 
 2 
 
 112 
 
 113 
 
 19 
 
 17 
 
 16 
 
 14 
 
 13 
 
 12 
 
 10 
 
 9 
 
 8 
 
 7 
 
 5 
 
 4 
 
 3 
 
 113 
 
 114 
 
 19 
 
 18 
 
 16 
 
 15 
 
 14 
 
 12 
 
 11 
 
 10 
 
 8 
 
 7 
 
 6 
 
 5 
 
 4 
 
 114 
 
 115 
 
 20 
 
 18 
 
 17 
 
 16 
 
 14 
 
 13 
 
 12 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 4 
 
 115 
 
 116 
 
 20 
 
 19 
 
 17 
 
 16 
 
 15 
 
 13 
 
 12 
 
 11 
 
 10 
 
 8 
 
 7 
 
 6 
 
 5 
 
 116 
 
 117 
 
 21 
 
 19 
 
 18 
 
 17 
 
 15 
 
 14 
 
 13 
 
 11 
 
 10 
 
 9 
 
 8 
 
 7 
 
 6 
 
 117 
 
 118 
 
 21 
 
 20 
 
 18 
 
 17 
 
 16 
 
 15 
 
 13 
 
 12 
 
 11 
 
 10 
 
 8 
 
 7 
 
 6 
 
 118 
 
 119 
 
 22 
 
 20 
 
 19 
 
 18 
 
 16 
 
 15 
 
 14 
 
 12 
 
 11 
 
 10 
 
 9 
 
 8 
 
 7 
 
 119 
 
 120 
 
 22 
 
 21 
 
 19 
 
 18 
 
 17 
 
 16 
 
 14 
 
 13 
 
 12 
 
 11 
 
 10 
 
 9 
 
 8 
 
 120 
 
 121 
 
 23 
 
 21 
 
 20 
 
 18 
 
 17 
 
 16 
 
 15 
 
 13 
 
 12 
 
 11 
 
 10 
 
 9 
 
 8 
 
 121 
 
 122 
 
 23 
 
 22 
 
 20 
 
 19 
 
 18 
 
 17 
 
 15 
 
 14 
 
 13 
 
 12 
 
 11 
 
 10 
 
 9 
 
 122 
 
 123 
 
 24 
 
 22 
 
 21 
 
 19 
 
 18 
 
 17 
 
 16 
 
 14 
 
 13 
 
 12 
 
 11 
 
 10 
 
 9 
 
 123 
 
 124 
 
 24 
 
 23 
 
 21 
 
 20 
 
 19 
 
 18 
 
 16 
 
 15 
 
 14 
 
 13 
 
 12 
 
 11 
 
 9 
 
 124 
 
 125 
 
 24 
 
 23 
 
 22 
 
 20 
 
 19 
 
 18 
 
 17 
 
 15 
 
 14 
 
 13 
 
 12 
 
 11 
 
 10 
 
 125 
 
 126 
 
 25 
 
 23 
 
 22 
 
 21 
 
 20 
 
 19 
 
 17 
 
 16 
 
 15 
 
 14 
 
 13 
 
 12 
 
 10 
 
 126 
 
 127 
 
 25 
 
 24 
 
 23 
 
 21 
 
 20 
 
 19 
 
 18 
 
 16 
 
 15 
 
 14 
 
 13 
 
 12 
 
 11 
 
 127 
 
 128 
 
 26 
 
 24 
 
 23 
 
 22 
 
 21 
 
 19 
 
 18 
 
 17 
 
 16 
 
 15 
 
 14 
 
 13 
 
 11 
 
 128 
 
 129 
 
 26 
 
 25 
 
 24 
 
 22 
 
 21 
 
 20 
 
 19 
 
 17 
 
 16 
 
 15 
 
 14 
 
 13 
 
 12 
 
 129 
 
 130 
 
 27 
 
 25 
 
 24 
 
 23 
 
 21 
 
 20 
 
 19 
 
 18 
 
 17 
 
 16 
 
 15 
 
 14 
 
 12 
 
 130 
 
 131 
 
 27 
 
 26 
 
 24 
 
 23 
 
 22 
 
 21 
 
 19 
 
 18 
 
 17 
 
 16 
 
 15 
 
 14 
 
 13 
 
 131 
 
 132 
 
 27 
 
 26 
 
 25 
 
 23 
 
 22 
 
 21 
 
 20 
 
 19 
 
 18 
 
 16 
 
 15 
 
 14 
 
 13 
 
 132 
 
 133 
 
 28 
 
 26 
 
 25 
 
 24 
 
 23 
 
 21 
 
 20 
 
 19 
 
 18 
 
 17 
 
 16 
 
 15 
 
 14 
 
 133 
 
 134 
 
 28 
 
 27 
 
 25 
 
 24 
 
 23 
 
 22 
 
 21 
 
 19 
 
 18 
 
 17 
 
 16 
 
 15 
 
 14 
 
 134 
 
 135 
 
 28 
 
 27 
 
 26 
 
 24 
 
 23 
 
 22 
 
 21 
 
 20 
 
 19 
 
 18 
 
 17 
 
 16 
 
 15 
 
 135 
 
 136 
 
 29 
 
 27 
 
 26 
 
 25 
 
 24 
 
 22 
 
 21 
 
 20 
 
 19 
 
 .18 
 
 17 
 
 16 
 
 15 
 
 136 
 
 137 
 
 29 
 
 28 
 
 26 
 
 25 
 
 24 
 
 23 
 
 22 
 
 20 
 
 19 
 
 18 
 
 17 
 
 16 
 
 15 
 
 137 
 
 138 
 
 29 
 
 28 
 
 27 
 
 25 
 
 24 
 
 23 
 
 22 
 
 21 
 
 20 
 
 19 
 
 18 
 
 17 
 
 16 
 
 138 
 
 139 
 
 30 
 
 28 
 
 27 
 
 26 
 
 25 
 
 24 
 
 22 
 
 21 
 
 20 
 
 19 
 
 18 
 
 17 
 
 16 
 
 139 
 
 140 
 
 30 
 
 29 
 
 28 
 
 2G 
 
 25 
 
 24 
 
 23 
 
 22 
 
 21 
 
 20 
 
 18 
 
 17 
 
 16 
 
 140 
 
 t. 
 
 36. 
 
 37. 
 
 38. 
 
 39. 
 
 40 c .O 
 
 41. 
 
 42. 
 
 43. 
 
 44. 
 
 45. 
 
 46. 
 
 47. 
 
 48. 
 
 t. 
 
91 
 
 TABLE III. Correction to vapor pressure for reading of barometer. 
 
 1 
 
 Inches. 
 
 
 p 
 
 
 
 7 
 
 30 
 
 29 
 
 28 
 
 27 
 
 26 
 
 25 
 
 24 
 
 23 
 
 22 
 
 21 
 
 20 
 
 19 
 
 18 
 
 T 
 
 . 
 
 .000 
 
 .000 
 
 + .001 
 
 + .001 
 
 +.001 
 
 + .002 
 
 +.002 
 
 + .003 
 
 +.003 
 
 + .003 
 
 + .004 
 
 +.004 
 
 +.004 
 
 i 
 
 2 
 
 .000 
 
 .000 
 
 .001 
 
 .002 
 
 .002 
 
 .003 
 
 .004 
 
 -.005 
 
 .006 
 
 .007 
 
 .007 
 
 .008 
 
 .009 
 
 2 
 
 3 
 
 .001 
 
 .000 
 
 .001 
 
 .002 
 
 .003 
 
 .004 
 
 .006 
 
 .007 
 
 .008 
 
 .009 
 
 .010 
 
 .011 
 
 .012 
 
 3 
 
 4 
 
 -.001 
 
 .000 
 
 .002 
 
 .003 
 
 .005 
 
 .006 
 
 .008 
 
 .009 
 
 .011 
 
 .012 
 
 .014 
 
 .015 
 
 .017 
 
 4 
 
 5 
 
 -.001 
 
 + .001 
 
 .002 
 
 .004 
 
 .006 
 
 .008 
 
 .010 
 
 .012 
 
 .014 
 
 .015 
 
 .017 
 
 .019 
 
 .021 
 
 5 
 
 G 
 
 001 
 
 001 
 
 003 
 
 005 
 
 008 
 
 010 
 
 .012 
 
 .014 
 
 016 
 
 019 
 
 021 
 
 .023 
 
 025 
 
 6 
 
 7 
 
 -.001 
 
 .001 
 
 .003 
 
 .006 
 
 .009 
 
 .012 
 
 .014 
 
 .017 
 
 .019 
 
 .022 
 
 .024 
 
 .027 
 
 .030 
 
 7 
 
 8 
 
 -.001 
 
 .001 
 
 .004 
 
 .007 
 
 .010 
 
 .013 
 
 .016 
 
 .019 
 
 .022 
 
 .025 
 
 .028 
 
 .031 
 
 .034 
 
 8 
 
 9 
 
 -.001 
 
 .002 
 
 .005 
 
 .008 
 
 .012 
 
 .015 
 
 .018 
 
 .022 
 
 .025 
 
 .028 
 
 .032 
 
 .035 
 
 .038 
 
 9 
 
 10 
 
 -.002 
 
 .002 
 
 .005 
 
 .009 
 
 .013 
 
 .017 
 
 .020 
 
 .024 
 
 .027 
 
 .031 
 
 .035 
 
 .039 
 
 .043 
 
 10 
 
 11 
 
 -.002 
 
 .002 
 
 .000 
 
 .010 
 
 .014 
 
 .018 
 
 .022 
 
 .026 
 
 .031 
 
 .035 
 
 .039 
 
 .043 
 
 .047 
 
 11 
 
 12 
 
 -.003 
 
 .002 
 
 .006 
 
 .010 
 
 .015 
 
 .019 
 
 .024 
 
 .028 
 
 .032 
 
 .037 
 
 .041 
 
 .046 
 
 .050 
 
 12 
 
 13 
 
 -.003 
 
 ' .002 
 
 .006 
 
 .011 
 
 .016 
 
 .021 
 
 .026 
 
 .030 
 
 .035 
 
 .040 
 
 .045 
 
 .050 
 
 .055 
 
 13 
 
 14 
 
 -.004 
 
 .002 
 
 .007 
 
 .012 
 
 .017 
 
 .022 
 
 .028 
 
 .033 
 
 .038 
 
 .043 
 
 .048 
 
 .054 
 
 .Oo9 
 
 14 
 
 15 
 
 -.004 
 
 .002 
 
 .007 
 
 .013 
 
 .019 
 
 .024 
 
 .030 
 
 .035 
 
 .041 
 
 .046 
 
 .052 
 
 .058 
 
 .063 
 
 15 
 
 16 
 
 004 
 
 002 
 
 .008 
 
 014 
 
 020 
 
 .026 
 
 .032 
 
 .038 
 
 .044 
 
 .049 
 
 .055 
 
 .061 
 
 067 
 
 16 
 
 17 
 
 -.004 
 
 .002 
 
 .008 
 
 .015 
 
 .021 
 
 .027 
 
 .034 
 
 .040 
 
 .046 
 
 .053 
 
 .059 
 
 .065 
 
 .072 
 
 17 
 
 18 
 
 -.004 
 
 .002 
 
 .009 
 
 .016 
 
 .022 
 
 .029 
 
 .036 
 
 .042 
 
 .049 
 
 .056 
 
 .062 
 
 .069 
 
 .076 
 
 18 
 
 19 
 
 -.005 
 
 .002 
 
 .009 
 
 .017 
 
 .024 
 
 .031 
 
 .038 
 
 .045 
 
 .052 
 
 .059 
 
 .066 
 
 .073 
 
 .080 
 
 19 
 
 20 
 
 .005 
 
 .003 
 
 .010 
 
 .018 
 
 .026 
 
 .033 
 
 .041 
 
 .048 
 
 .055 
 
 .063 
 
 .070 
 
 .078 
 
 .085 
 
 20 
 
 21 
 
 .005 
 
 .003 
 
 .011 
 
 .019 
 
 .027 
 
 .034 
 
 .042 
 
 .050 
 
 .057 
 
 .066 
 
 .073 
 
 .081 
 
 .089 
 
 21 
 
 22 
 
 .005 
 
 .003 
 
 .011 
 
 .020 
 
 .028 
 
 .036 
 
 .044 
 
 .052 
 
 .061 
 
 .069 
 
 .077 
 
 .085 
 
 .093 
 
 22 
 
 -23 
 
 .005 
 
 .003 
 
 .012 
 
 .021 
 
 .029 
 
 .038 
 
 .046 
 
 .055 
 
 .063 
 
 .072 
 
 .081 
 
 .089 
 
 .098 
 
 23 
 
 24 
 
 .005 
 
 .004 
 
 .013 
 
 .021 
 
 .030 
 
 .039 
 
 .048 
 
 .057 
 
 .066 
 
 .075 
 
 .084 
 
 .093 
 
 .102 
 
 24 
 
 25 
 
 .006 
 
 .004 
 
 .013 
 
 .022 
 
 .032 
 
 .041 
 
 .050 
 
 .060 
 
 .069 
 
 .078 
 
 .088 
 
 .097 
 
 .106 
 
 25 
 
 26 
 
 .006 
 
 .004 
 
 .013 
 
 .023 
 
 .033 
 
 .043 
 
 .052 
 
 .062 
 
 .072 
 
 .081 
 
 .091 
 
 .101 
 
 .111 
 
 26 
 
 27 
 
 .006 
 
 .004 
 
 .014 
 
 .024 
 
 .034 
 
 .044 
 
 .054 
 
 .065 
 
 .075 
 
 .085 
 
 .095 
 
 .105 
 
 .115 
 
 27 
 
 28 
 
 -.006 
 
 .004 
 
 .015 
 
 .025 
 
 .036 
 
 .046 
 
 .056 
 
 .067 
 
 .077 
 
 .088 
 
 .098 
 
 .109 
 
 .119 
 
 28 
 
 29 
 
 .007 
 
 .004 
 
 .015 
 
 .026 
 
 .037 
 
 .048 
 
 .059 
 
 .069 
 
 .080 
 
 .091 
 
 .102 
 
 .113 
 
 .124 
 
 29 
 
 30 
 
 .007 
 
 .004 
 
 .016 
 
 .027 
 
 .038 
 
 .049 
 
 .061 
 
 .072 
 
 .083 
 
 .094 
 
 .105 
 
 .117 
 
 .128 
 
 30 
 
 31 
 
 .007 
 
 .005 
 
 .016 
 
 .028 
 
 .039 
 
 .051 
 
 .063 
 
 .074 
 
 .086 
 
 .097 
 
 .109 
 
 .121 
 
 .132 
 
 31 
 
 32 
 
 .007 
 
 .005 
 
 .017 
 
 .029 
 
 .041 
 
 .053 
 
 .065 
 
 .077 
 
 .089 
 
 .101 
 
 .113 
 
 .125 
 
 .137 
 
 32 
 
 33 
 
 .007 
 
 .005 
 
 .017 
 
 .030 
 
 .042 
 
 .054 
 
 .067 
 
 .079 
 
 .092 
 
 .104 
 
 .116 
 
 .129 
 
 .141 
 
 33 
 
 34 
 
 .008 
 
 .005 
 
 .018 
 
 .031 
 
 .043 
 
 .056 
 
 .069 
 
 .082 
 
 .094 
 
 .107 
 
 .120 
 
 .133 
 
 .145 
 
 34 
 
 35 
 
 .008 
 
 .005 
 
 .018 
 
 .032 
 
 .045 
 
 .058 
 
 .071 
 
 .084 
 
 .097 
 
 .110 
 
 .123 
 
 .137 
 
 .150 
 
 35 
 
 36 
 
 .008 
 
 .005 
 
 .019 
 
 .032 
 
 .046 
 
 .059 
 
 .073 
 
 .086 
 
 .100 
 
 .114 
 
 .127 
 
 .141 
 
 .154 
 
 36 
 
 37 
 
 .008 
 
 .006 
 
 .019 
 
 .033 
 
 .047 
 
 .061 
 
 .075 
 
 .089 
 
 .103 
 
 .117 
 
 .131 
 
 .145 
 
 .158 
 
 37 
 
 38 
 
 v.009 
 
 .006 
 
 .020 
 
 .034 
 
 .049 
 
 .063 
 
 .077 
 
 .091 
 
 .106 
 
 .120 
 
 .134 
 
 .149 
 
 .163 
 
 38 
 
 39 
 
 .009 
 
 .006 
 
 .021 
 
 .035 
 
 .050 
 
 .065 
 
 .079 
 
 .094 
 
 .109 
 
 .123 
 
 .138 
 
 .153 
 
 .167 
 
 39 
 
 40 
 
 .009 
 
 +.006 
 
 +.021 
 
 +.036 
 
 +.051 
 
 + .066 
 
 +.081 
 
 + .096 
 
 +.111 
 
 +.126 
 
 + .142 
 
 +.157 
 
 + .172 
 
 40 
 
 Dew Point 
 Pressure 
 
 Correction. 
 
92 
 
 TABLE IV. Vapor pressure, in inches. 
 
 
 E 
 
 
 g 
 
 
 i 
 
 
 i 
 
 
 g 
 
 
 e 
 
 
 g 
 
 
 
 
 I 
 
 
 
 
 D 
 
 
 1 
 
 
 1 
 
 
 
 a 
 
 o> 
 
 "a 
 
 I 
 
 a 
 
 o> 
 
 c 
 
 g 
 
 a 
 
 1 
 
 "S 
 
 E 
 
 d 
 
 E 
 
 I 
 
 h 
 
 a 
 
 p. 
 
 'I 
 
 
 
 1 
 
 !_ 
 
 'I 
 
 a 
 
 S-i 
 
 a 
 
 5 
 
 a 
 
 5 
 
 : 
 
 a 
 
 s 
 
 o 
 0, 
 
 y. 
 
 1 
 
 k 
 
 a 
 
 
 a 
 
 
 o 
 a 
 
 
 a 
 
 
 cS 
 
 01 
 
 
 
 
 0> 
 
 cS 
 
 
 cj 
 
 
 
 o 
 
 
 
 ft 
 
 ps> 
 
 ft 
 
 ^f 
 
 ft 
 
 > 
 
 ft 
 
 
 n 
 
 
 
 Q 
 
 |^r 
 
 ft 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 60 
 
 .0010 
 
 30 
 
 .0069 
 
 
 
 .038 
 
 30 
 
 .164 
 
 60 
 
 .517 
 
 90 
 
 1.408 
 
 120 
 
 3.425 
 
 59 
 
 .0011 
 
 29 
 
 .0074 
 
 1 
 
 .040 
 
 31 
 
 .172 
 
 61 
 
 .536 
 
 91 
 
 1.453 
 
 121 
 
 3. 522 
 
 58 
 
 .0012 
 
 28 
 
 .0078 
 
 2 
 
 .043 
 
 32 
 
 .180 
 
 62 
 
 .555 
 
 92 
 
 1. 499 
 
 122 
 
 3.621 
 
 57 
 
 .0013 
 
 27 
 
 .0084 
 
 3 
 
 .045 
 
 33 
 
 .187 
 
 63 
 
 .575 
 
 93 
 
 1.546 
 
 123 
 
 3. 723 
 
 56 
 
 .0013 
 
 26 
 
 .0089 
 
 4 
 
 .047 
 
 34 
 
 .195 
 
 64 
 
 .595 
 
 94 
 
 1. 595 
 
 124 
 
 3.827 
 
 55 
 
 .0015 
 
 25 
 
 .0094 
 
 5 
 
 .049 
 
 35 
 
 .203 
 
 65 
 
 .616 
 
 95 
 
 1. 645 
 
 125 
 
 3.933 
 
 54 
 
 .0016 
 
 24 
 
 .010 
 
 6 
 
 .052 
 
 36 
 
 .211 
 
 66 
 
 .638 
 
 96 
 
 1.696 
 
 126 
 
 4.042 
 
 53 
 
 .0017 
 
 23 
 
 .011 
 
 7 
 
 .054 
 
 37 
 
 .219 
 
 67 
 
 .660 
 
 97 
 
 1.749 
 
 127 
 
 4.154 
 
 52 
 
 .0018 
 
 22 
 
 .011 
 
 8 
 
 .057 
 
 38 
 
 .228 
 
 68 
 
 .684 
 
 98 
 
 1.803 
 
 128 
 
 4.268 
 
 51 
 
 .0019 
 
 21 
 
 .012 
 
 9 
 
 .060 
 
 39 
 
 . 237 
 
 69 
 
 .707 
 
 99 
 
 1.859 
 
 129 
 
 4.385 
 
 50 
 
 .0021 
 
 20 
 
 .013 
 
 *10 
 
 .063 
 
 40 
 
 .246 
 
 70 
 
 .732 
 
 100 
 
 1.916 
 
 130 
 
 4.504 
 
 49 
 
 .0022 
 
 19 
 
 .013 
 
 11 
 
 .067 
 
 41 
 
 .256 
 
 71 
 
 .757 
 
 101 
 
 1.975 
 
 131 
 
 4.627 
 
 48 
 
 .0024 
 
 18 
 
 .014 
 
 12 
 
 .070 
 
 42 
 
 .266 
 
 72 
 
 .783 
 
 102 
 
 2.035 
 
 132 
 
 4. 752 
 
 47 
 
 .0026 
 
 17 
 
 .015 
 
 13 
 
 .074 
 
 43 
 
 .277 
 
 73 
 
 .810 
 
 103 
 
 2.097 
 
 133 
 
 4.880 
 
 46 
 
 .0027 
 
 16 
 
 .016 
 
 14 
 
 .077 
 
 44 
 
 .287 
 
 74 
 
 .838 
 
 104 
 
 2. 160 
 
 134 
 
 5.011 
 
 45 
 
 .0029 
 
 15 
 
 .017 
 
 15 
 
 .081 
 
 45 
 
 .298 
 
 75 
 
 .866 
 
 105 
 
 2.225 
 
 135 
 
 5.145 
 
 44 
 
 .00:51 
 
 14 
 
 .018 
 
 16 
 
 .085 
 
 46 
 
 .310 
 
 76 
 
 .896 
 
 106 
 
 2. 292 
 
 136 
 
 5.282 
 
 43 
 
 .0033 
 
 13 
 
 .019 
 
 17 
 
 .089 
 
 47 
 
 .322 
 
 77 
 
 .926 
 
 107 
 
 2.360 
 
 137 
 
 5.422 
 
 42 
 
 .0035 
 
 12 
 
 .020 
 
 18 
 
 .093 
 
 48 
 
 .334 
 
 78 
 
 .957 
 
 108 
 
 2.431 
 
 138 
 
 5.565 
 
 41 
 
 .0037 
 
 11 
 
 .021 
 
 19 
 
 .098 
 
 49 
 
 .347 
 
 79 
 
 .989 
 
 109 
 
 2.503 
 
 139 
 
 5.712 
 
 40 
 
 .0039 
 
 10 
 
 .022 
 
 20 
 
 .103 
 
 50 
 
 .360 
 
 80 
 
 1.022 
 
 110 
 
 2.576 
 
 140 
 
 5.862 
 
 39 
 
 .0041 
 
 9 
 
 .023 
 
 21 
 
 .108 
 
 51 
 
 .373 
 
 81 
 
 1.056 
 
 111 
 
 2.652 
 
 
 
 38 
 
 .0044 
 
 8 
 
 .025 
 
 22 
 
 .113 
 
 52 
 
 .387 
 
 82 
 
 1.091 
 
 112 
 
 2.730 
 
 
 
 37 
 
 .0046 
 
 - 7 
 
 .026 
 
 23 
 
 .119 
 
 53 
 
 .402 
 
 83 
 
 1. 127 
 
 113 
 
 2. 810 
 
 
 
 36 
 
 .0048 
 
 6 
 
 .028 
 
 24 
 
 .125 
 
 54 
 
 .417 
 
 84 
 
 1.163 
 
 114 
 
 2.891 
 
 
 
 35 
 
 .0051 
 
 5 
 
 .029 
 
 25 
 
 .130 
 
 55 
 
 .432 
 
 85 
 
 1.202 
 
 115 
 
 2.975 
 
 
 
 34 
 
 .0054 
 
 4 
 
 .031 
 
 26 
 
 .137 
 
 56 
 
 .448 
 
 86 
 
 1.241 
 
 116 
 
 3.061 
 
 
 
 33 
 
 .0058 
 
 3 
 
 .033 
 
 27 
 
 .143 
 
 57 
 
 .465 
 
 87 
 
 1.281 
 
 117 
 
 3.148 
 
 
 
 32 
 
 .0061 
 
 2 
 
 .034 
 
 28 
 
 .150 
 
 58 
 
 .481 
 
 88 
 
 1.322 
 
 118 
 
 3. 239 
 
 
 
 31 
 
 .0065 
 
 1 
 
 .036 
 
 29 
 
 .157 
 
 59 
 
 .499 
 
 89 
 
 1.364 
 
 119 
 
 3.331 
 
 
 
 Vapor 
 
 Pros- 
 
 sure. 
 
93 
 
 TABLE V. Grains of water-vapor contained in a cubic foot of air. 
 
 J 
 
 
 
 
 
 
 
 
 
 
 
 3 
 
 
 
 1 
 
 2 
 
 3 
 
 4 
 
 5 
 
 6 
 
 7 
 
 8 
 
 9 
 
 I 
 
 
 
 
 
 
 
 
 
 
 
 j 
 
 
 
 
 
 
 
 
 
 
 
 20 
 
 .219 
 
 
 
 
 
 
 
 
 
 
 10 
 
 .356 
 
 .340 
 
 .324 
 
 .309 
 
 .294 
 
 .281 
 
 .267 
 
 .254 
 
 .242 
 
 .231 
 
 
 
 .564 
 
 .540 
 
 .516 
 
 .493 
 
 .471 
 
 .450 
 
 .430 
 
 .411 
 
 .391 
 
 .374 
 
 + o 
 
 .564 
 
 .590 
 
 .617 
 
 .645 
 
 .674 
 
 .705 
 
 .735 
 
 .767 
 
 .801 
 
 .837 
 
 10 
 
 .87C 
 
 .910 
 
 .950 
 
 .991 
 
 1.033 
 
 1.075 
 
 1.122 
 
 1.169 
 
 1.217 
 
 1.268 
 
 20 
 
 1.321 
 
 1.374 
 
 1.430 
 
 1.488 
 
 1.550 
 
 1.611 
 
 1.675 
 
 1.743 
 
 1.812 
 
 1.884 
 
 30 
 
 1. 958 
 
 2.034 
 
 2.113 
 
 2.194 
 
 2.279 
 
 2.366 
 
 2.457 
 
 2.550 
 
 2.646 
 
 2.746 
 
 40 
 
 2.8*9 
 
 2.955 
 
 3.064 
 
 3.177 
 
 3.294 
 
 3.414 
 
 3.539 
 
 3.667 
 
 3.800 
 
 3.936 
 
 50 
 
 4.076 
 
 4.222 
 
 4.372- 
 
 4.526 
 
 4.685 
 
 4.849 
 
 5.01& 
 
 5.191 
 
 5.371 
 
 5.555 
 
 60 
 
 5.744 
 
 5.941 
 
 6.142 
 
 6. 350 
 
 6.563 
 
 6.782 
 
 7.009 
 
 7.241 
 
 7.480 
 
 7.726 
 
 70 
 
 7.980 
 
 8.240 
 
 8.508 
 
 8.782 
 
 9.065 
 
 9. 356 
 
 9.655 
 
 9.961 
 
 10. 277 
 
 10.601 
 
 80 
 
 10. 933 
 
 11. 275 
 
 11.626 
 
 11.987 
 
 12. 356 
 
 12. 736 
 
 13. 127 
 
 13. 576 
 
 13. 937 
 
 14.358 
 
 90 
 
 14. 791 
 
 15. 234 
 
 15. 688 
 
 16. 155 
 
 16. 634 
 
 17. 124 
 
 17. 626 
 
 18. 142 
 
 18. 671 
 
 19. 212 
 
 100 
 
 19. 766 
 
 20. 335 
 
 20. 917 
 
 21.514 
 
 22. 125 
 
 22. 751 
 
 
 
 
 
94 
 
 TABLE VI. Reduction of barometer reading to 32. 
 
 Tempera- 
 ture. 
 
 Inches. 
 
 24.0 
 
 24.5 
 
 25.0 
 
 25.5 
 
 26.0 
 
 26.5 
 
 27.0 
 
 27.5 
 
 28.0 
 
 +.073 
 .070 
 .068 
 .065 
 .063 
 
 .060 
 
 .058 
 .055 
 
 28.5 
 
 29.0 
 
 29.5 
 
 30.0 
 
 30.5 
 
 31.0 
 
 +.081 
 .078 
 .075 
 .072 
 .070 
 
 .067 
 .064 
 061 
 
 
 1 
 2 
 3 
 4 
 
 5 
 6 
 7 
 8 
 9 
 
 10 
 11 
 12 
 13 
 14 
 
 15 
 16 
 17 
 18 
 19 
 
 20 
 21 
 22 
 23 
 24 
 
 25 
 26 
 27 
 28 
 29 
 
 30 
 31 
 32 
 33 
 34 
 
 35 
 36 
 37 
 38 
 39 
 
 40 
 41 
 42 
 43 
 44 
 
 45 
 46 
 47 
 48 
 49 
 
 50 
 
 + .063 
 .060 
 .058 
 .056 
 .054 
 
 .052 
 .049 
 .047 
 .045 
 .043 
 
 +.064 
 .062 
 .060 
 .057 
 .055 
 
 .052 
 .051 
 .048 
 .046 
 .044 
 
 +.065 
 .063 
 .061 
 .058 
 .056 
 
 .054 
 .052 
 .049 
 .047 
 .045 
 
 +.067 
 .064 
 .062 
 .060 
 .057 
 
 .055 
 .052 
 .050 
 .048 
 .046 
 
 + .068 
 .065 
 .063 
 .061 
 .058 
 
 .056 
 .054 
 .051 
 
 +.069 +.070 
 . 067 . t68 
 .065 .065 
 . 062 . 063 
 .060 .061 
 
 .057' .058 
 . 055 . 056 
 . 052' . 053 
 
 +.072 
 .Oi.9 
 .066 
 .064 
 .062 
 
 .059 
 .057 
 .054 
 
 +.075 
 .072 
 .069 
 .066 
 .064 
 
 .062 
 .059 
 056 
 
 +.076 
 .073 
 .070 
 .068 
 .065 
 
 .062 
 .060 
 057 
 
 +.077 
 .074 
 ,072 
 .069 
 .066 
 
 .063 
 .061 
 058 
 
 +.078 
 .076 
 .073 
 .070 
 .067 
 
 .065 
 .062 
 059 
 
 +.080 
 .077 
 .074 
 .071 
 .068 
 
 .065 
 .063 
 060 
 
 .049 
 .046 
 
 .050 
 .047 
 
 .051 
 .048 
 
 .052 
 .049 
 
 .053 
 .050 
 
 .054 
 .051 
 
 .054 
 052 
 
 .055 
 .053 
 
 .050 
 .047 
 .045 
 .042 
 .039 
 
 .056 
 .054 
 
 .051 
 .048 
 .045 
 .043 
 .040 
 
 .057 
 .054 
 
 .052 
 .049 
 .046 
 .043 
 040 
 
 .058 
 .055 
 
 .053 
 .050 
 .047 
 .044 
 041 
 
 .041 
 
 .039 
 .036 
 .034 
 .032 
 
 .042 
 .039 
 .037 
 .035 
 .033 
 
 .042 
 .040 
 .038 
 .036 
 .033 
 
 .043 
 .041 
 .038 
 .036 
 .034 
 
 .044 
 
 .042 
 .039 
 .037 
 035 
 
 .045 
 .042 
 .040 
 .038 
 .035 
 
 .046 
 .043 
 .041 
 .038 
 .036 
 
 .047 
 .044 
 .041 
 .039 
 .036 
 
 .047 
 .045 
 .042 
 .040 
 .037 
 
 .048 
 .046 
 .043 
 .040 
 .038 
 
 .049 
 .047 
 .044 
 .041 
 039 
 
 .030 
 
 .028 
 .025 
 .023 
 .021 
 
 .030 
 .028 
 .026 
 .024 
 .022 
 
 .031 
 
 .029 
 .026 
 .024 
 .022 
 
 .031 
 
 .029 
 .027 
 .025 
 .022 
 
 .032 
 
 .030 
 .027 
 .025 
 023 
 
 .033 .033 
 .030 .031 
 .028 .029 
 .026 .026 
 . 023 . 024 
 
 .034 
 .031 
 .029 
 .026 
 024 
 
 .035 
 
 .032 
 .030 
 .027 
 .025 
 
 .035 
 .033 
 .030 
 .027 
 025 
 
 .036 
 .033 
 . 031 
 
 .028 
 .025 
 
 .036 
 .034 
 .031 
 .029 
 026 
 
 .087 
 .035 
 .032 
 .029 
 027 
 
 .038 
 .035 
 .032 
 .030 
 027 
 
 .038 
 .036 
 .033 
 .030 
 .027 
 
 .019 
 .017 
 .014 
 
 .019 
 .017 
 .015 
 
 .020 
 .017 
 .015 
 
 .020 
 .018 
 .015 
 
 .020 
 .018 
 016 
 
 .021 
 
 .018 
 .016 
 
 .021 
 .019 
 .016 
 
 .021 
 .019 
 .017 
 
 .022 
 .019 
 .017 
 
 .022 
 .020 
 .017 
 
 .023 
 . 020 
 .017 
 
 .023 
 .020 
 018 
 
 .024 
 .021 
 .018 
 
 .024 
 .021 
 .018 
 .016 
 .013 
 
 .024 
 .022 
 .019 
 .016 
 .013 
 
 .012 
 .010 
 
 .013 
 .010 
 
 .013 
 .011 
 
 .013 
 .011 
 
 .013 
 Oil 
 
 .014 
 .011 
 
 .014 
 .011 
 
 .014 
 .012 
 
 .014 
 .012 
 
 .015 
 012 
 
 .015 
 012 
 
 .015 
 012 
 
 .015 
 .013 
 
 .008 
 .006 
 .004 
 +.001 
 001 
 
 .008 
 .006 
 .004 
 +.001 
 001 
 
 .008 
 .006 
 .004 
 +.001 
 001 
 
 .008 
 .006 
 .004 
 +.001 
 001 
 
 .009 
 
 .006 
 .004 
 
 +.001 
 001 
 
 .009 
 
 .006 
 .004 
 +.002 
 001 
 
 . OO!) 
 .006 
 .004 
 + .002 
 .001 
 
 .009 
 
 .007 
 .004 
 +.002 
 .001 
 
 .009 
 .007 
 .004 
 + .002 
 001 
 
 .009 
 .007 
 .004 
 + .002 
 001 
 
 .010 
 .007 
 .004 
 + .002 
 .001 
 
 .010 
 .007 
 .004 
 +.002 
 .001 
 
 .010 
 .007 
 .004 
 + .002 
 .001 
 
 .010 
 .007 
 .005 
 + .002 
 .001 
 
 .010 
 .007 
 .005 
 + .002 
 .001 
 
 .003 
 
 003 
 
 .003 
 
 003 
 
 003 
 
 .003 
 
 .003 
 
 .003 
 
 003 
 
 .004 
 
 .004 
 
 .004 
 
 .004 
 
 .004 
 
 .004 
 
 .005 
 .007 
 .010 
 012 
 
 .005 
 .008 
 .010 
 012 
 
 .005 
 .008 
 .010 
 .012 
 
 .005 
 .008 
 .010 
 012 
 
 .006 
 .008 
 .010 
 013 
 
 .006 
 .008 
 .010 
 013 
 
 .006 
 .008 
 .011 
 013 
 
 .006 
 .008 
 .011 
 013 
 
 .006 
 .009 
 .011 
 .014 
 
 .006 
 .009 
 .011 
 014 
 
 .006 
 .009 
 .012 
 .014 
 
 .006 
 .009 
 .012 
 014 
 
 .006 
 .009 
 .012 
 .015 
 
 .007 
 .009 
 .012 
 015 
 
 .007 
 .009 
 .012 
 .015 
 
 .014 
 .016 
 .018 
 .020 
 .023 
 
 025 
 
 .014 
 .016 
 .019 
 .021 
 .023 
 
 025 
 
 .014 
 .017 
 .019 
 .021 
 .024 
 
 026 
 
 .015 
 .017 
 .019 
 .022 
 .024 
 
 026 
 
 .015 
 .017 
 .020 
 .022 
 .024 
 
 027 
 
 .015 
 .018 
 .020 
 .022 
 .025 
 
 - 027 
 
 .016 
 .018 
 .021 
 .023 
 .025 
 
 028 
 
 .016 
 .018 
 .021 
 .023 
 .026 
 
 028 
 
 .016 
 .019 
 .021 
 .024 
 .026 
 
 .029 
 
 .016 
 .019 
 .022 
 .024 
 .027 
 
 030 
 
 .017 
 .019 
 .022 
 .025 
 .027 
 
 030 
 
 .017 
 .020 
 .022 
 .025 
 .028 
 
 030 
 
 .017 
 .020 
 .023 
 .026 
 .028 
 
 .031 
 
 .018 
 .020 
 .023 
 .026 
 .029 
 
 031 
 
 .018 
 .021 
 .024 
 .026 
 .029 
 
 .032 
 
 .027 
 .029 
 .031 
 .033 
 
 .036 
 .038 
 .040 
 .042 
 .044 
 
 .046 
 
 .027 
 .030 
 .032 
 .034 
 
 .037 
 
 .038 
 .041 
 .043 
 .045 
 
 .047 
 
 .028 
 .030 
 .033 
 .035 
 
 .037 
 .039 
 .042 
 .044 
 .046 
 
 .048 
 
 .029 
 .031 
 .033 
 .035 
 
 .038 
 .040 
 .042 
 .045 
 .047 
 
 .049 
 
 .029 
 .032 
 .034 
 .036 
 
 .039 
 .041 
 .043 
 .046 
 .048 
 
 .060 
 
 .030 
 .032 
 .035 
 .037 
 
 .039 
 
 .042 
 .044 
 .047 
 .049 
 
 .051 
 
 .0:50 
 .033 
 .035 
 .038 
 
 .040 
 .043 
 .045 
 .047 
 .050 
 
 .052 
 
 .031 
 .033 
 .036 
 .038 
 
 .041 
 .043 
 .046 
 .048 
 .051 
 
 .053 
 
 .031 
 .034 
 .036 
 .039 
 
 .042 
 .044 
 .047 
 .0^9 
 .052 
 
 .054 
 
 .032 
 .034 
 .037 
 .040 
 
 .042 
 .045 
 .0^8 
 .050 
 .052 
 
 .055 
 
 .033 
 .035 
 .038 
 .040 
 
 .043 
 .0^6 
 .048 
 .051 
 .054 
 
 -.056 
 
 .033 
 .036 
 .038 
 .041 
 
 .044 
 .04C 
 .049 
 .052 
 .054 
 
 -.057 
 
 .034 
 .036 
 .039 
 .042 
 
 .045 
 .047 
 .050 
 .053 
 .055 
 
 .058 
 
 .034 
 .037 
 .040 
 .042 
 
 .045 
 .048 
 .051 
 .053 
 .056 
 
 -.059 
 
 .035 
 .038 
 .040 
 .043 
 
 .046 
 .049 
 .052 
 .054 
 .057 
 
 -.060 
 
95 
 
 TABLE VI Reduction of barometer reading to 32 Continued. 
 
 a 
 
 
 
 
 
 
 
 
 Inche 
 
 5. 
 
 
 
 
 
 
 
 I 5 
 
 24.0 
 
 24.5 
 
 25.0 
 
 25.5 
 
 26.0 
 
 26,5 
 
 27.0 
 
 27.5 
 
 28.0 
 
 28.5 
 
 29.0 
 
 29.5 
 
 30.0 
 
 30.5 
 
 31.0 
 
 50 
 
 .046 
 
 .047 
 
 .048 
 
 .049 
 
 . 050 
 
 .051 
 
 .052 
 
 . 053 
 
 .054 
 
 -.055 
 
 .056 
 
 .057 
 
 .058 
 
 .059 
 
 .060 
 
 51 
 
 .049 
 
 .050 
 
 .051 
 
 .052 
 
 .053 
 
 .054 
 
 .055 
 
 .056 
 
 .057 
 
 .058 
 
 .059 
 
 .060 
 
 .061 
 
 .062 
 
 .063 
 
 52 
 
 .051 
 
 .052 
 
 .053 
 
 .054 
 
 .055 
 
 .056 
 
 .057 
 
 .058 
 
 .059 
 
 .060 
 
 .061 
 
 .062 
 
 .064 
 
 .065 
 
 .066 
 
 53 
 
 .053 
 
 .054 
 
 .055 
 
 .056 
 
 .057 
 
 .058 
 
 .060 
 
 .061 
 
 .062 
 
 .063 
 
 .064 
 
 .065 
 
 .066 
 
 .067 
 
 .068 
 
 54 
 
 .055 
 
 .056 
 
 .057 
 
 .058 
 
 .060 
 
 .061 
 
 .062 
 
 .063 
 
 .064 
 
 .065 
 
 .067 
 
 .068 
 
 .069 
 
 .070 
 
 .071 
 
 55 
 
 .057 
 
 .058 
 
 .060 
 
 .061 
 
 .062 
 
 .063 
 
 .064 
 
 .065 
 
 .066 
 
 .068 
 
 .06,9 
 
 .070 
 
 .071 
 
 .073 
 
 .074 
 
 56 
 
 .060 
 
 .061 
 
 .062 
 
 .063 
 
 .064 
 
 .065 
 
 .067 
 
 .0(38 
 
 .069 
 
 .070 
 
 .072 
 
 .073 
 
 .074 
 
 .075 
 
 .077 
 
 57 
 
 OfiV! 
 
 .063 
 
 .064 
 
 .065 
 
 .067 
 
 .068 
 
 .069 
 
 .070 
 
 072 
 
 073 
 
 075 
 
 076 
 
 077 
 
 078 
 
 080 
 
 58 
 
 .0(14 
 
 .065 
 
 .066 
 
 .068 
 
 .069 
 
 .070 
 
 .071 
 
 .073 
 
 .074 
 
 .076 
 
 .077 
 
 .078 
 
 .080 
 
 .081 
 
 .082 
 
 59 
 
 .056 
 
 .068 
 
 .069 
 
 .070 
 
 .072 
 
 .073 
 
 .074 
 
 .075 
 
 .077 
 
 .078 
 
 .080 
 
 .'081 
 
 .083 
 
 .084 
 
 .085 
 
 60 
 
 .068 
 
 .070 
 
 .071 
 
 .072 
 
 .074 
 
 .076 
 
 .077 
 
 .078 
 
 .079 
 
 .081 
 
 .082 
 
 .084 
 
 .085 
 
 .086 
 
 .088 
 
 61 
 
 .070 
 
 .072 
 
 .073 
 
 .074 
 
 .076 
 
 .077 
 
 .079 
 
 .080 
 
 .082 
 
 .083 
 
 .085 
 
 .086 
 
 .088 
 
 .089 
 
 .091 
 
 62 
 
 .073 
 
 .074 
 
 .076 
 
 .077 
 
 .079 
 
 .080 
 
 .082 
 
 .083 
 
 .085 
 
 .036 
 
 .088 
 
 .089 
 
 .091 
 
 .092 
 
 .094 
 
 63 
 
 .075 
 
 .076 
 
 .078 
 
 .079 
 
 .081 
 
 .082 
 
 .084 
 
 .085 
 
 .087 
 
 .088 
 
 .090 
 
 .091 
 
 .093 
 
 .095 
 
 .096 
 
 64 
 
 .077 
 
 .078 
 
 .080 
 
 .081 
 
 .083 
 
 .085 
 
 .086 
 
 .088 
 
 .090 
 
 .091 
 
 .093 
 
 .094 
 
 .096 
 
 .097 
 
 .099 
 
 65 
 
 .079 
 
 .080 
 
 .082 
 
 .084 
 
 .086 
 
 .087 
 
 .089 
 
 .090 
 
 .092 
 
 .093 
 
 .095 
 
 .097 
 
 .099 
 
 .100 
 
 .102 
 
 66 
 
 .081 
 
 ,083 
 
 .085 
 
 .086 
 
 .088 
 
 .089 
 
 .091 
 
 .093 
 
 .095 
 
 .096 
 
 .098 
 
 .099 
 
 .101 
 
 .103 
 
 .105 
 
 67 
 
 .083 
 
 .085 
 
 .087 
 
 .088 
 
 .090 
 
 .092 
 
 .094 
 
 .095 
 
 .097 
 
 .099 
 
 .101 
 
 .102 
 
 .104 
 
 .106 
 
 .108 
 
 68 
 
 .085 
 
 .087 
 
 .089 
 
 .090 
 
 .093 
 
 .094 
 
 .096 
 
 .098 
 
 .100 
 
 .101 
 
 .103 
 
 .105 
 
 .107 
 
 .108 
 
 .110 
 
 69 
 
 .088 
 
 .089 
 
 .091 
 
 .093 
 
 .095 
 
 .097 
 
 .099 
 
 .100 
 
 .102 
 
 .104 
 
 .106 
 
 .107 
 
 .110 
 
 .111 
 
 .113 
 
 70 
 
 .090 
 
 .092 
 
 .094 
 
 .096 
 
 .097 
 
 .099 
 
 .101 
 
 .103 
 
 .105 
 
 .106 
 
 .109 
 
 .110 
 
 .112 
 
 .114 
 
 .116 
 
 71 
 
 .092 
 
 .094 
 
 .096 
 
 .098 
 
 .100 
 
 .101 
 
 .103 
 
 .105 
 
 .107 
 
 .109 
 
 .111 
 
 .113 
 
 .115 
 
 .116 
 
 .119 
 
 72 
 
 .094 
 
 .096 
 
 .098 
 
 .100 
 
 .102 
 
 .104 
 
 .106 
 
 .108 
 
 .110 
 
 .112 
 
 .114 
 
 .116 
 
 .118 
 
 .120 
 
 .122 
 
 73 
 
 .096 
 
 .098 
 
 .100 
 
 .102 
 
 .104 
 
 .106 
 
 .108 
 
 .110 
 
 .112 
 
 .114 
 
 .116 
 
 .118 
 
 .120 
 
 .122 
 
 .124 
 
 74 
 
 .098 
 
 .100 
 
 .103 
 
 .105 
 
 107 
 
 .109 
 
 .111 
 
 .113 
 
 .115 
 
 .117 
 
 .119 
 
 .121 
 
 .123 
 
 .126 
 
 .127 
 
 75 
 
 .101 
 
 .102 
 
 .105 
 
 .106 
 
 .109 
 
 .111 
 
 .113 
 
 .115 
 
 .117 
 
 .119 
 
 .122 
 
 .124 
 
 .126 
 
 .128 
 
 .130 
 
 76 
 
 .103 
 
 .104 
 
 .107 
 
 .109 
 
 .111 
 
 .113 
 
 .116 
 
 .118 
 
 .120 
 
 .122 
 
 .124 
 
 .126 
 
 .128 
 
 .130 
 
 .133 
 
 77 
 
 .105 
 
 .107 
 
 .109 
 
 .111 
 
 .114 
 
 .116 
 
 .118 
 
 .120 
 
 .122 
 
 .124 
 
 .127 
 
 .129 
 
 .131 
 
 .133 
 
 .136 
 
 78 
 
 .107 
 
 .109 
 
 .112 
 
 .113 
 
 .116 
 
 .118 
 
 .120 
 
 .122 
 
 .125 
 
 .127 
 
 .129 
 
 .131 
 
 .134 
 
 .136 
 
 .138 
 
 79 
 
 .109 
 
 .111 
 
 .114 
 
 .116 
 
 .118 
 
 .120 
 
 .123 
 
 .125 
 
 .127 
 
 .129 
 
 .132 
 
 .134 
 
 .137 
 
 .139 
 
 .141 
 
 80 
 
 111 
 
 113 
 
 116 
 
 118 
 
 121 
 
 123 
 
 .125 
 
 127 
 
 .130 
 
 .132 
 
 .135 
 
 .137 
 
 139 
 
 .141 
 
 .144 
 
 81 
 
 .114 
 
 .116 
 
 .118 
 
 .120 
 
 .123 
 
 .125 
 
 .128 
 
 .130 
 
 .132 
 
 .134 
 
 .137 
 
 .139 
 
 .142 
 
 .144 
 
 .147 
 
 82 
 
 .116 
 
 .118 
 
 .121 
 
 .122 
 
 .125 
 
 .128 
 
 .130 
 
 .132 
 
 .135 
 
 .137 
 
 .140 
 
 .142 
 
 .145 
 
 .147 
 
 .149 
 
 83 
 
 .118 
 
 .120 
 
 .123 
 
 .125 
 
 .128 
 
 .130 
 
 .133 
 
 .135 
 
 .138 
 
 .140 
 
 .142 
 
 .145 
 
 .147 
 
 .149 
 
 .152 
 
 84 
 
 .120 
 
 .122 
 
 .125 
 
 .127 
 
 .130 
 
 .132 
 
 .135 
 
 .138 
 
 .140 
 
 .142 
 
 .145 
 
 .147 
 
 .150 
 
 .152 
 
 .155 
 
 85 
 
 .122 
 
 .124 
 
 .127 
 
 .129 
 
 .132 
 
 .134 
 
 .137 
 
 .139 
 
 .143 
 
 .145 
 
 .148 
 
 .150 
 
 .153 
 
 .155 
 
 .158 
 
 86 
 
 .124 
 
 .126 
 
 .128 
 
 .130 
 
 .135 
 
 .137 
 
 .140 
 
 .143 
 
 .145 
 
 .148 
 
 .150 
 
 .153 
 
 .155 
 
 .158 
 
 .161 
 
 87 
 
 .126 
 
 .129 
 
 .132 
 
 .134 
 
 .137 
 
 .139 
 
 .142 
 
 .144 
 
 .148 
 
 .150 
 
 .153 
 
 .155 
 
 .158 
 
 .161 
 
 .163 
 
 88 
 
 .129 
 
 .131 
 
 .134 
 
 .137 
 
 .139 
 
 .142 
 
 .145 
 
 .147 
 
 .150 
 
 .152 
 
 .155 
 
 .158 
 
 .161 
 
 .163 
 
 .166 
 
 89 
 
 .131 
 
 .133 
 
 .136 
 
 .139 
 
 .142 
 
 .144 
 
 .147 
 
 .150 
 
 .153 
 
 .155 
 
 .158 
 
 .161 
 
 .164 
 
 .166 
 
 .169 
 
 90 
 
 .133 
 
 .136 
 
 .138 
 
 .141 
 
 .144 
 
 .147 
 
 .150 
 
 .153 
 
 .155 
 
 .157 
 
 .161 
 
 .164 
 
 .166 
 
 .169 
 
 .172 
 
 91 
 
 .135 
 
 .138 
 
 .141 
 
 .143 
 
 .146 
 
 .149 
 
 .152 
 
 .155 
 
 .158 
 
 .160 
 
 .163 
 
 .166 
 
 .169 
 
 .172 
 
 .175 
 
 92 
 
 .137 
 
 .140 
 
 .143 
 
 .146 
 
 .149 
 
 .152 
 
 .154 
 
 .157 
 
 .160 
 
 .163 
 
 .166 
 
 .169 
 
 .172 
 
 .175 
 
 .177 
 
 93 
 
 .139 
 
 .142 
 
 .145 
 
 .148 
 
 .151 
 
 .154 
 
 .157 
 
 .160 
 
 .163 
 
 .166 
 
 .168 
 
 .171 
 
 .174 
 
 .177 
 
 .180 
 
 94 
 
 .142 
 
 .145 
 
 .147 
 
 .150 
 
 .153 
 
 .156 
 
 .159 
 
 .162 
 
 .165 
 
 .168 
 
 .171 
 
 .174 
 
 .177 
 
 .180 
 
 .183 
 
 95 
 
 .141 
 
 .147 
 
 .150 
 
 .153 
 
 .156 
 
 .159 
 
 .162 
 
 .165 
 
 .168 
 
 .171 
 
 .174 
 
 .177 
 
 .180 
 
 .183 
 
 .186 
 
 96 
 
 .146 
 
 .149 
 
 .152 
 
 .155 
 
 .158 
 
 .161 
 
 .164 
 
 .167 
 
 .170 
 
 .173 
 
 .176 
 
 .179 
 
 .182 
 
 .185 
 
 .188 
 
 97 
 
 .148 
 
 .151 
 
 .154 
 
 .157 
 
 .160 
 
 .164 
 
 .167 
 
 .170 
 
 .173 
 
 .176 
 
 .179 
 
 .182 
 
 .185 
 
 .188 
 
 .191 
 
 98 
 
 .150 
 
 .153 
 
 .156 
 
 .160 
 
 .163 
 
 .166 
 
 .169 
 
 .172 
 
 .175 
 
 .178 
 
 .181 
 
 .185 
 
 .188 
 
 .191 
 
 .194 
 
 99 
 
 .152 
 
 .155 
 
 .159 
 
 .162 
 
 .165 
 
 .168 
 
 .171 
 
 .175 
 
 .178 
 
 .181 
 
 .184 
 
 .187 
 
 .190 
 
 .194 
 
 .197 
 
 100 
 
 .154 
 
 .157 
 
 .161 
 
 .164 
 
 .167 
 
 .171 
 
 -.174 
 
 -.177 
 
 .180 
 
 .184 
 
 -.187 
 
 .190 
 
 -.193 
 
 .197 
 
 .200 
 
96 
 
 TABLE VII. Table for reducing observations of the barometer to sea-level, correction additive. 
 
 a 
 
 Temperature of external air degrees Fahrenheit. 
 
 El 
 .1 
 
 20 
 
 10 
 
 
 
 10 
 
 20 
 
 30 
 
 40 
 
 50 
 
 60 
 
 70 
 
 80 
 
 90 
 
 100 
 
 10 
 
 .013 
 
 .013 
 
 .012 
 
 .012 
 
 .012 
 
 .012 
 
 .011 
 
 .011 
 
 .011 
 
 .011 
 
 .010 
 
 .010 
 
 .010 
 
 20 
 
 .026 
 
 .025 
 
 .025 
 
 .024 
 
 .023 
 
 .023 
 
 023 
 
 022 
 
 .022 
 
 021 
 
 021 
 
 020 
 
 020 
 
 30 
 
 .039 
 
 .038 
 
 .037 
 
 .036 
 
 .035 
 
 .034 
 
 .034 
 
 .033 
 
 .032 
 
 .032 
 
 .031 
 
 .030 
 
 .030 
 
 40 
 
 .052 
 
 .050 
 
 .049 
 
 .048 
 
 .047 
 
 .046 
 
 .045 
 
 . .044 
 
 .043 
 
 .042 
 
 .041 
 
 .040 
 
 .040 
 
 50 
 
 .065 
 
 .063 
 
 .061 
 
 .060 
 
 .059 
 
 .058 
 
 .056 
 
 .055 
 
 .054 
 
 .053 
 
 .052 
 
 .051 
 
 .050 
 
 60 
 
 .077 
 
 .076 
 
 .074 
 
 .072 
 
 .070 
 
 .069 
 
 .068 
 
 .066 
 
 .065 
 
 .063 
 
 .062 
 
 .061 
 
 .059 
 
 70 
 
 .090 
 
 .088 
 
 .086 
 
 084 
 
 082 
 
 .081 
 
 078 
 
 .077 
 
 076 
 
 074 
 
 072 
 
 071 
 
 069 
 
 80 
 
 .103 
 
 .101 
 
 .098 
 
 .096 
 
 .094 
 
 .092 
 
 .090 
 
 .088 
 
 .086 
 
 .084 
 
 .082 
 
 .081 
 
 .079 
 
 yd 
 
 .116 
 
 .113 
 
 .111 
 
 .108 
 
 105 
 
 104 
 
 101 
 
 .099 
 
 097 
 
 095 
 
 093 
 
 091 
 
 089 
 
 100 
 
 .129 
 
 .126 
 
 .123 
 
 .120 
 
 117 
 
 115 
 
 112 
 
 .110 
 
 108 
 
 105 
 
 .103 
 
 101 
 
 099 
 
 110 
 
 .142 
 
 .139 
 
 .135 
 
 .132 
 
 .129 
 
 .126 
 
 .123 
 
 .121 
 
 .119 
 
 .116 
 
 .113 
 
 .111 
 
 .109 
 
 120 
 
 .155 
 
 .151 
 
 .148 
 
 .144 
 
 .140 
 
 .138 
 
 .134 
 
 .132 
 
 .129 
 
 .126 
 
 .124 
 
 .121 
 
 .119 
 
 130 
 
 .168 
 
 .164 
 
 .160 
 
 .156 
 
 .152 
 
 .149 
 
 .146 
 
 .143 
 
 .140 
 
 .137 
 
 .134 
 
 .131 
 
 .129 
 
 140 
 
 .181 
 
 .176 
 
 .172 
 
 .168 
 
 .164 
 
 .161 
 
 .157 
 
 .154 
 
 .151 
 
 .147 
 
 .144 
 
 .141 
 
 .139 
 
 150 
 
 .194 
 
 .189 
 
 .185 
 
 .180 
 
 .176 
 
 .172 
 
 .168 
 
 .165 
 
 .162 
 
 .158 
 
 . 155 
 
 .152 
 
 .149 
 
 160 
 
 .206 
 
 .201 
 
 .197 
 
 .192 
 
 .187 
 
 .183 
 
 .179. 
 
 .176 
 
 .172 
 
 .168 
 
 .165 
 
 . 162 
 
 .158 
 
 170 
 
 .219 
 
 .214 
 
 .209 
 
 .204 
 
 .199 
 
 .195 
 
 .190 
 
 .187 
 
 .183 
 
 .179 
 
 .175 
 
 .172 
 
 .168 
 
 180 
 
 .232 
 
 .227 
 
 .222 
 
 .216 
 
 .211 
 
 .206 
 
 .202 
 
 .198 
 
 .194 
 
 .189 
 
 .185 
 
 .182 
 
 .178 
 
 190 
 
 .245 
 
 .239 
 
 .234 
 
 .228 
 
 .222 
 
 .218 
 
 .213 
 
 .209 
 
 .204 
 
 .200 
 
 .196 
 
 .192 
 
 ..188 
 
 200 
 
 .258 
 
 ' .252 
 
 .246 
 
 .240 
 
 .234 
 
 .229 
 
 .224 
 
 .220 
 
 .215 
 
 .210 
 
 .206 
 
 .202 
 
 .198 
 
 210 
 
 .271 
 
 .264 
 
 .258 
 
 .252 
 
 246 
 
 240 
 
 .235 
 
 .231 
 
 226 
 
 .221 
 
 .216 
 
 .212 
 
 208 
 
 220 
 
 .284 
 
 .277 
 
 .270 
 
 .264 
 
 .257 
 
 .252 
 
 .246 
 
 .242 
 
 .236 
 
 .231 
 
 .227 
 
 .222 
 
 .218 
 
 230 
 
 .296 
 
 .289 
 
 .283 
 
 .276 
 
 269 
 
 263 
 
 .257 
 
 253 
 
 247 
 
 .242 
 
 .237 
 
 .232 
 
 228 
 
 240 
 
 .309 
 
 .302 
 
 .295 
 
 .288 
 
 .281 
 
 .275 
 
 .269 
 
 .264 
 
 .258 
 
 .252 
 
 .248 
 
 .242 
 
 .238 
 
 250 
 
 .322 
 
 .314 
 
 .307 
 
 .300 
 
 .293 
 
 .286 
 
 .280 
 
 .275 
 
 .269 
 
 .263 
 
 .258 
 
 .253 
 
 .248 
 
 260 
 
 .335 
 
 .327 
 
 .319 
 
 311 
 
 304 
 
 297 
 
 291 
 
 285 
 
 279 
 
 .273 
 
 .268 
 
 .263 
 
 257 
 
 270 
 
 .348 
 
 .339 
 
 .331 
 
 .323 
 
 .316 
 
 .309 
 
 .302 
 
 .296 
 
 .290 
 
 .284 
 
 .278 
 
 .273 
 
 .267 
 
 280 
 
 .3(50 
 
 .352 
 
 .344 
 
 .335 
 
 .328 
 
 .320 
 
 .314 
 
 .307 
 
 .301 
 
 .294 
 
 .288 
 
 .283 
 
 .277 
 
 290 
 
 .373 
 
 .364 
 
 .356 
 
 .347 
 
 .339 
 
 .332 
 
 .325 
 
 .318 
 
 .311 
 
 .305 
 
 .299 
 
 .293 
 
 .287 
 
 300 
 
 .386 
 
 .377 
 
 .368 
 
 .359 
 
 .351 
 
 .343 
 
 .336 
 
 .329 
 
 .322 
 
 .315 
 
 .309 
 
 .303 
 
 .297 
 
 310 
 
 .399 
 
 .389 
 
 .380 
 
 .371 
 
 .363 
 
 .354 
 
 .347 
 
 .340 
 
 .333 
 
 .326 
 
 .319 
 
 .313 
 
 .307 
 
 320 
 
 .412 
 
 .402 
 
 .392 
 
 .383 
 
 .374 
 
 .366 
 
 .358 
 
 .351 
 
 .343 
 
 .336 
 
 .329 
 
 .323 
 
 .317 
 
 330 
 
 .424 
 
 .414 
 
 .404 
 
 .395 
 
 .386 
 
 .377 
 
 .369 
 
 .362 
 
 . .354 
 
 .347 
 
 .340 
 
 .333 
 
 .326 
 
 340 
 
 .437 
 
 .427 
 
 .416 
 
 .407 
 
 .397 
 
 .389 
 
 .380 
 
 .373 
 
 .365 
 
 .357 
 
 .350 
 
 .343 
 
 .336 
 
 350 
 
 .450 
 
 .439 
 
 .429 
 
 .419 
 
 .409 
 
 .400 
 
 .392 
 
 .384 
 
 .376 
 
 .368 
 
 .360 
 
 .353 
 
 .346 
 
 360 
 
 .463 
 
 .451 
 
 .441 
 
 .430 
 
 .421 
 
 .411 
 
 .403 
 
 .394 
 
 .386 
 
 .378 
 
 .370 
 
 .363 
 
 .356 
 
 370 
 
 .476 
 
 .464 
 
 .453 
 
 .442 
 
 .432 
 
 .423 
 
 .414 
 
 .405 
 
 .397 
 
 .389 
 
 .380 
 
 .373 
 
 .366 
 
 380 
 
 .488 
 
 .476 
 
 .465 
 
 .454 
 
 .444 
 
 .434 
 
 .425 
 
 .416 
 
 .408 
 
 .399 
 
 .391 
 
 .383 
 
 .375 
 
 390 
 
 .501 
 
 .489 
 
 .477 
 
 .466 
 
 .455 
 
 .446 
 
 .436 
 
 .427 
 
 .418 
 
 .410 
 
 .401 
 
 .393 
 
 .385 
 
 400 
 
 .514 
 
 .501 
 
 .489 
 
 .478 
 
 .467 
 
 .457 
 
 .447 
 
 .438 
 
 .429 
 
 .420 
 
 .411 
 
 .403 
 
 .395 
 
 410 
 
 .527 
 
 .513 
 
 .501 
 
 .490 
 
 .479 
 
 .468 
 
 .458 
 
 .449 
 
 .440 
 
 .430 
 
 .421 
 
 .413 
 
 .405 
 
 420 
 
 .539 
 
 .526 
 
 .513 
 
 .502 
 
 .490 
 
 .480 
 
 .469 
 
 .460 
 
 .450 
 
 .441 
 
 .431 
 
 .423 
 
 .415 
 
 430 
 
 .552 
 
 .538 
 
 .525 
 
 .513 
 
 .502 
 
 .491 
 
 .480 
 
 .470 
 
 .461 
 
 .451 
 
 .442 
 
 .433 
 
 .425 
 
 440 
 
 .565 
 
 .551 
 
 .537 
 
 .525 
 
 .513 
 
 .502 
 
 .491 
 
 .481 
 
 .471 
 
 .462 
 
 .452 
 
 .443 
 
 .434 
 
 450 
 
 .578 
 
 .563 
 
 .550 
 
 .537 
 
 .525 
 
 .513 
 
 .503 
 
 .492 
 
 .482 
 
 .472 
 
 .462 
 
 .453 
 
 .444 
 
 460 
 
 .590 
 
 .575 
 
 .562 
 
 .549 
 
 .537 
 
 .525 
 
 .514 
 
 .503 
 
 .493 
 
 .482 
 
 .472 
 
 .463 
 
 .454 
 
 470 
 
 .603 
 
 .588 
 
 .574 
 
 .561 
 
 .548 
 
 .536 
 
 .525 
 
 .514 
 
 .503 
 
 .493 
 
 .482 
 
 .473 
 
 .464 
 
 480 
 
 .616 
 
 .600 
 
 .586 
 
 .572 
 
 .560 
 
 .547 
 
 .536 
 
 .524 
 
 .514 
 
 .503 
 
 .493 
 
 .483 
 
 .474 
 
 490 
 
 .628 
 
 .613 
 
 .598 
 
 .584 
 
 .571 
 
 .559 
 
 .547 
 
 .535 
 
 .524 
 
 .514 
 
 .503 
 
 .493 
 
 .483 
 
 500 
 
 .641 
 
 .625 
 
 .610 
 
 .596 
 
 .583 
 
 .570 
 
 .558 
 
 .646 
 
 .535 
 
 .524 
 
 .513 
 
 .503 
 
 .493 
 
 510 
 
 .654 
 
 .637 
 
 .622 
 
 .608 
 
 .594 
 
 .581 
 
 .569 
 
 .557 
 
 .545 
 
 .534 
 
 .523 
 
 .513 
 
 .503 
 
 520 
 
 .666 
 
 .650 
 
 .634 
 
 .620 
 
 .606 
 
 .593 
 
 .580 
 
 .568 
 
 .556 
 
 .545 
 
 .533 
 
 .523 
 
 .513 
 
 530 
 
 .679 
 
 .662 
 
 .646 
 
 .631 
 
 .617 
 
 .604 
 
 .591 
 
 .578 
 
 .566 
 
 .555 
 
 .544 
 
 .533 
 
 .522 
 
 540 
 
 .691 
 
 .675 
 
 .658 
 
 .643 
 
 .629 
 
 .615 
 
 .602 
 
 .589 
 
 .577 
 
 .565 
 
 .554 
 
 .543 
 
 .532 
 
 550 
 
 .704 
 
 .687 
 
 .670 
 
 .655 
 
 .640 
 
 .626 
 
 .613 
 
 .600 
 
 .587 
 
 .575 
 
 .564 
 
 .553 
 
 .542 
 
 560 
 
 .717 
 
 .699 
 
 .683 
 
 .667 
 
 .652 
 
 .638 
 
 .624 
 
 .611 
 
 .598 
 
 .586 
 
 .574 
 
 .563 
 
 .552 
 
 570 
 
 .729 
 
 .712 
 
 .695 
 
 .679 
 
 .663 
 
 .649 
 
 .635 
 
 .622 
 
 .608 
 
 .596 
 
 .584 
 
 .573 
 
 .562 
 
 580 
 
 .742 
 
 .724 
 
 .707 
 
 .690 
 
 .675 
 
 .660 
 
 .646 
 
 .632 
 
 .619 
 
 .606 
 
 .595 
 
 .583 
 
 .571 
 
 590 
 
 .754 
 
 .737 
 
 .719 
 
 .702 
 
 .686 
 
 .672 
 
 .657 
 
 .643 
 
 .629 
 
 .617 
 
 .605 
 
 .593 
 
 .581 
 
 600 
 
 .767 
 
 .749 
 
 .731 
 
 .714 
 
 .698 
 
 .683 
 
 .668 
 
 .654 
 
 .640 
 
 .627 
 
 .615 
 
 .603 
 
 .591 
 
 610 
 
 .780 
 
 .761 
 
 .743 
 
 .726 
 
 .709 
 
 .694 
 
 .679 
 
 .665 
 
 .650 
 
 .637 
 
 .625 
 
 .613 
 
 .601 
 
 620 
 
 .792 
 
 .774 
 
 .755 
 
 .738 
 
 .721 
 
 .705 
 
 .690 
 
 .675 
 
 .661 
 
 .648 
 
 .635 
 
 .623 
 
 .611 
 
 630 
 
 .805 
 
 .786 
 
 .767 
 
 .749 
 
 .732 
 
 .717 
 
 .701 
 
 .686 
 
 .671 
 
 .658 
 
 .645 
 
 .633 
 
 .620 
 
 640 
 
 .817 
 
 ,798 
 
 ,779 
 
 ,761 
 
 ,744 
 
 ,728 
 
 ,712 
 
 .697 
 
 .682 
 
 .668 
 
 .655 
 
 .643 
 
 .630 
 
97 
 
 TABLE VII. For reducing observations, etc. Continued. 
 
 _g 
 
 Temperature of external air degrees Fahrenheit. 
 
 |1 
 H 
 
 20 
 
 10 
 
 
 
 10 
 
 20 30 
 
 40 
 
 50 
 
 60 
 
 70 
 
 800 
 
 90 
 
 100 
 
 
 
 
 
 
 
 
 i 
 
 
 
 
 
 650 
 
 .830 
 
 .811 
 
 .791 
 
 .773 
 
 .755 
 
 .739 
 
 .723 
 
 .708 
 
 .692 
 
 .679 
 
 .666 
 
 .653 
 
 .640 
 
 660 
 
 .843 
 
 .823 
 
 .803 
 
 .785 
 
 .767 
 
 .750 
 
 .734 
 
 .718 
 
 .703 
 
 .689 
 
 .676 
 
 .662 
 
 .650 
 
 670 
 
 .855 
 
 .835 
 
 .815 
 
 .797 
 
 .778 
 
 .761 
 
 .745 
 
 .729 
 
 .713 
 
 .699 
 
 .686 
 
 .672 
 
 .660 
 
 680 
 
 .868 
 
 .847 
 
 .827 
 
 .808 
 
 .790 
 
 .773 
 
 .756 
 
 .740 
 
 .724 
 
 .709 
 
 .696 
 
 .682 
 
 .669 
 
 690 
 
 .880 
 
 .860 
 
 .839 
 
 .820 
 
 .801 
 
 .784 
 
 .767 
 
 .750 
 
 .734 
 
 .720 
 
 .706 
 
 .692 
 
 .679 
 
 700 
 
 .893 
 
 .872 
 
 .851 
 
 .832 
 
 .813 
 
 .795 
 
 .778 
 
 .761 
 
 .745 
 
 .730 
 
 .716 
 
 .702 
 
 .689 
 
 710 
 
 .905 
 
 .884 
 
 .863 
 
 .844 
 
 .824 
 
 .806 
 
 .789 
 
 .772 
 
 .755 
 
 .740 
 
 .726 
 
 .712 
 
 .698 
 
 720 
 
 .918 
 
 .896 
 
 .875 
 
 .855 
 
 .836 
 
 .817 
 
 .800 
 
 .782 
 
 .766 
 
 .751 
 
 .736 
 
 .722 
 
 .708 
 
 730 
 
 .930 
 
 .909 
 
 .887 
 
 .867 
 
 .847 
 
 .829 
 
 .811 
 
 .793 
 
 .776 
 
 .761 
 
 .746 
 
 .732 
 
 .718 
 
 740 
 
 .943 
 
 .921 
 
 .899 
 
 .879 
 
 .859 
 
 .840 
 
 .822 
 
 .804 
 
 .787 
 
 .771 
 
 .756 
 
 .742 
 
 .728 
 
 750 
 
 .955 
 
 .933 
 
 .911 
 
 .891 
 
 .870 
 
 .851 
 
 .833 
 
 .815 
 
 .797 
 
 .782 
 
 .767 
 
 .752 
 
 .738 
 
 760 
 
 .968 
 
 .945 
 
 .922 
 
 .902 
 
 .881 
 
 .862 
 
 .843 
 
 .825 
 
 .808 
 
 .792 
 
 .777 
 
 .761 
 
 .747 
 
 770 
 
 .980 
 
 .957 
 
 .934 
 
 .914 
 
 .893 
 
 .873 
 
 .854 
 
 .836 
 
 .818 
 
 .802 
 
 .787 
 
 .771 
 
 .757 
 
 780 
 
 .993 
 
 .970 
 
 .946 
 
 .926 
 
 .904 
 
 .885 
 
 .865 
 
 .847 
 
 .829 
 
 .812 
 
 .797 
 
 .781 
 
 .767 
 
 790 
 
 1.005 
 
 .982 
 
 .958 
 
 .937 
 
 .916 
 
 .896 
 
 .876 
 
 .857 
 
 .839 
 
 .823 
 
 .807 
 
 .791 
 
 .776 
 
 800 
 
 1.018 
 
 .994 
 
 .970 
 
 .949 
 
 .927 
 
 .907 
 
 .887 
 
 .868 
 
 .850 
 
 .833 
 
 .817 
 
 .801 
 
 .786 
 
 810 
 
 1.030 
 
 1.00*6 
 
 .982 
 
 .961 
 
 .938^ 
 
 .918 
 
 .898 
 
 .878 
 
 .860 
 
 .843 
 
 .827 
 
 .811 
 
 .796 
 
 820 
 
 1.043 
 
 1.018 
 
 .994 
 
 .972 
 
 .050 
 
 .929 
 
 .909 
 
 .889 
 
 .871 
 
 .854 
 
 .837 
 
 .821 
 
 .805 
 
 830 
 
 1 055 
 
 1.031 
 
 1. 006 
 
 .984 
 
 .961 
 
 .940 
 
 920 
 
 900 
 
 .881 
 
 864 
 
 847 
 
 831 
 
 .815 
 
 840 
 
 1.068 
 
 1.043 
 
 1.018 
 
 .995 
 
 .973 
 
 .951 
 
 .931 
 
 .911 
 
 .892 
 
 .874 
 
 .857 
 
 .841 
 
 
 850 
 
 1.080 
 
 1.055 
 
 1.030 
 
 1.007 
 
 .984 
 
 .962 
 
 .942 
 
 .922 
 
 .902 
 
 .885 
 
 .867 
 
 .851 
 
 .835 
 
 860 
 
 1.093 
 
 1.067 
 
 1.041 
 
 1.019 
 
 .995 
 
 .974 
 
 .952 
 
 .932 
 
 .913 
 
 .895 
 
 .877 
 
 860 
 
 .844 
 
 870 
 
 1.105 
 
 1.079 
 
 1.053 
 
 1.030 
 
 1.007 
 
 .985 
 
 .963 
 
 .943 
 
 .923 
 
 .905 
 
 .887 
 
 .870 
 
 .854 
 
 880 
 
 1.118 
 
 1.092 
 
 1.065 
 
 1.042 
 
 1.018 
 
 .996 
 
 .974 
 
 .954 
 
 .934 
 
 .915 
 
 .897 
 
 .880 
 
 .864 
 
 890 
 
 1.130 
 
 1.104 
 
 1.077 
 
 1.053 
 
 1.030 
 
 1.007 
 
 .985 
 
 .964 
 
 944 
 
 926 
 
 907 
 
 890 
 
 .873 
 
 900 
 
 1.143 
 
 1.116 
 
 1.089 
 
 1.065 
 
 1.041 
 
 1.018 
 
 .996 
 
 .975 
 
 .955 
 
 .936 
 
 .917 
 
 .900 
 
 .883 
 
 910 
 
 1.155 
 
 1.128 
 
 1.101 
 
 1.077 
 
 1.052 
 
 1.029 
 
 1.007 
 
 .986 
 
 .965 
 
 .946 
 
 .927 
 
 .910 
 
 .893 
 
 920 
 
 1.168 
 
 1.140 
 
 1.113 
 
 1.088 
 
 1.064 
 
 1.040 
 
 1.018 
 
 .996 
 
 .976 
 
 .956 
 
 .937 
 
 .920 
 
 .902 
 
 930 
 
 1.180 
 
 1.152 
 
 1. 125 
 
 1.100 
 
 1.075 
 
 1.051 
 
 1.029 
 
 1.007 
 
 .986 
 
 .967 
 
 .947 
 
 .929 
 
 .912 
 
 940 
 
 1.193 
 
 1.164 
 
 1.137 
 
 1.111 
 
 1.086 
 
 1.062 
 
 1.040 
 
 1.017 
 
 .997 
 
 .977 
 
 .957 
 
 .939 
 
 .921 
 
 950 
 
 1.205 
 
 1.177 
 
 1.149 
 
 1.123 
 
 1.098 
 
 1.074 
 
 1.051 
 
 1.028 
 
 1.007 
 
 .987 
 
 .967 
 
 .949 
 
 .931 
 
 960 
 
 1.217 
 
 1.189 
 
 1.160 
 
 1.135 
 
 1. 109 
 
 1.085 
 
 1.061 
 
 1.039 
 
 1.017 
 
 .997 
 
 .977 
 
 .959 
 
 .941 
 
 970 
 
 1.230 
 
 1.201 
 
 1.172 
 
 1.146 
 
 1.120 
 
 1.096 
 
 1.072 
 
 1.049 
 
 1.028 
 
 1.007 
 
 .987 
 
 .969 
 
 .950 
 
 980 
 
 1.242 
 
 1.213 
 
 1.184 
 
 1.158 
 
 1.131 
 
 1.107 
 
 1.083 
 
 1.060 
 
 1.038 
 
 1.018 
 
 .997 
 
 .978 
 
 .960 
 
 990 
 
 1.255 
 
 1.225 
 
 1.196 
 
 1.169 
 
 1.143 
 
 1.118 
 
 1.094 
 
 1.070 
 
 1.049 
 
 1.028 
 
 1,007 
 
 .988 
 
 .969 
 
 1,000 
 
 1.267 
 
 1.237 
 
 1.208 
 
 1.181 
 
 1.154 
 
 1.129 
 
 1.105 
 
 1.081 
 
 1.059 
 
 1.038 
 
 1.017 
 
 .998 
 
 .979 
 
 1,010 
 
 1.279 
 
 1.249 
 
 1.220 
 
 1.192 
 
 1. 165 
 
 1.140 
 
 1.116 
 
 1.092 
 
 1.069 
 
 1.048 
 
 1.027 
 
 1.008 
 
 .989 
 
 1,020 
 
 1.292 
 
 1.261 
 
 1.232 
 
 1.204 
 
 1.177 
 
 1.151 
 
 1.127 
 
 1.102 
 
 1.080 
 
 1.058 
 
 1.037 
 
 1.018 
 
 .998 
 
 1,030 
 
 1.304 
 
 1.273 
 
 1.243 
 
 1.215 
 
 1.188 
 
 1.162 
 
 1.137 
 
 1.113 
 
 1.090 
 
 1.069 
 
 1.047 
 
 1.027 
 
 1.008 
 
 1,040 
 
 1.317 
 
 1.285 
 
 1.255 
 
 1. 227 
 
 1.199 
 
 1.173 
 
 1.148 
 
 1.123 
 
 1.101 
 
 1.079 
 
 1.057 
 
 1.037 
 
 1.017 
 
 1,050 
 
 1.329 
 
 1.298 
 
 1.267 
 
 1.238 
 
 1.211 
 
 1.184 
 
 1.159 
 
 1.134 
 
 1.111 
 
 1.089 
 
 1.067 
 
 1.047 
 
 1.027 
 
 1,060 
 
 1.341 
 
 1.310 
 
 1.279 
 
 1.250 
 
 1.222 
 
 1.195 
 
 1.170 
 
 1.145 
 
 1.121 
 
 1.099 
 
 1.077 
 
 1.057 
 
 1.037 
 
 1,070 
 
 1.354 
 
 1/322 
 
 1.291 
 
 1.261 
 
 1.233 
 
 1.206 
 
 1.181 
 
 1.155 
 
 1. 132 
 
 1.109 
 
 1.087 
 
 1.067 
 
 1.046 
 
 1,080 
 
 1.366 
 
 1.334 
 
 1 302 
 
 1 273 
 
 1 244 
 
 1 217 
 
 1 191 
 
 1 166 
 
 1 142 
 
 1.120 
 
 1 097 
 
 1 076 
 
 1 056 
 
 1J090 
 
 1.379 
 
 1.346 
 
 1.314 
 
 1.284 
 
 1.256 
 
 1.228 
 
 1.202 
 
 1.176 
 
 1.153 
 
 1.130 
 
 1.107 
 
 1.086 
 
 1.065 
 
 1,100 
 
 1.391 
 
 1.358 
 
 1.326 
 
 1. 296 
 
 1.267 
 
 1.239 
 
 1.213 
 
 1.187 
 
 1.163 
 
 1.140 
 
 1.117 
 
 1.096 
 
 1.075 
 
 1,110 
 
 1.403 
 
 1.370 
 
 1.338 
 
 1.307 
 
 1.278 
 
 1.250 
 
 1.224 
 
 1.198 
 
 1.173 
 
 1.150 
 
 1.127 
 
 1.106 
 
 1.085 
 
 1,120 
 
 1.416 
 
 1.382 
 
 1.350 
 
 1.319 
 
 1.289 
 
 1.261 
 
 1.235 
 
 1.208 
 
 1.184 
 
 1.160 
 
 1.137 
 
 1.115 
 
 1.094 
 
 1,130 
 
 1.428 
 
 1. 394 
 
 1.361 
 
 1.330 
 
 1.301 
 
 1.272 
 
 1.245 
 
 1.219 
 
 1.194 
 
 1.170 
 
 1.147 
 
 1.125 
 
 1.104 
 
 1,140 
 
 1.440 
 
 1.406 
 
 1.373 
 
 1. 342 
 
 1.312 
 
 1.283 
 
 1.256 
 
 1.229 
 
 1.204 
 
 1.180 
 
 1.157 
 
 1.135 
 
 1.113 
 
 1,150 
 
 1.453 
 
 1.418 
 
 1.385 
 
 1.353 
 
 1.323 
 
 1.294 
 
 1.267 
 
 1.240 
 
 1.215 
 
 1.191 
 
 1.167 
 
 1.145 
 
 1.123 
 
 1,160 
 
 1.465 
 
 1.430 
 
 1.397 
 
 1.365 
 
 1.334 
 
 1.305 
 
 1.278 
 
 1.251 
 
 1.225 
 
 1.201 
 
 1.177 
 
 1.154 
 
 1.133 
 
 1,170 
 
 1.477 
 
 1.442 
 
 1.409 
 
 1.376 
 
 1.345 
 
 1.315 
 
 1.289 
 
 1.261 
 
 1.235 
 
 1.211 
 
 1.187 
 
 1.164 
 
 1.142 
 
 1,180 
 
 1.489 
 
 1.454 
 
 1.420 
 
 1.388 
 
 1.357 
 
 1. 327 
 
 1.299 
 
 1.272 
 
 1.245 
 
 1.221 
 
 1.197 
 
 1.174 
 
 1.152 
 
 1,190 
 
 1.502 
 
 1.466 
 
 1.432 
 
 1.399 
 
 1.368 
 
 1.338 
 
 1.310 
 
 1.282 
 
 1.256 
 
 1.231 
 
 1.207 
 
 1.183 
 
 1.161 
 
 1 200 
 
 1.514 
 
 1.478 
 
 1.444 
 
 1.411 
 
 1.379 
 
 1.349 
 
 1.321 
 
 1.293 
 
 1.266 
 
 1.241 
 
 1.217 
 
 1.193 
 
 1.171 
 
 1,210 
 
 1.526 
 
 1.490 
 
 1.456 
 
 1.422 
 
 1.390 
 
 1.360 
 
 1.332 
 
 1.303 
 
 1.276 
 
 1.251 
 
 1.227 
 
 1.203 
 
 1.180 
 
 1,220 
 
 1. 539 
 
 1. 502 
 
 1.467 
 
 1.434 
 
 1.401 
 
 1.371 
 
 1.342 
 
 1.314 
 
 1.288 
 
 1.261 
 
 1.237 
 
 1.212 
 
 1.190 
 
 1,230 
 
 1.551 
 
 1.514 
 
 1.479 
 
 1.445 
 
 1.413 
 
 1.382 
 
 1.353 
 
 1.324 
 
 1.297 
 
 1.271 
 
 1.247 
 
 1.222 
 
 1.199 
 
 1,240 
 
 1.563 
 
 1.526 
 
 1.491 
 
 1.457 
 
 1.424 
 
 1.393 
 
 1.364 
 
 1.335 
 
 1.307 
 
 1.281 
 
 1.257 
 
 1.232 
 
 1.209 
 
 1,250 
 
 1. 576 
 
 1. 538 
 
 1.502 
 
 1.468 
 
 1.435 
 
 1.404 
 
 1.374 
 
 1.345 
 
 1.317 
 
 1.291 
 
 1.266 
 
 1.242 
 
 1.218 
 
 1,260 
 
 1.588 
 
 1.550 
 
 1.514 
 
 1.479 
 
 1.446 
 
 1.415 
 
 1.385 
 
 1.356 
 
 1.328 
 
 1.302 
 
 1.276 
 
 1.251 
 
 1. 228 
 
 1,270 
 
 1.600 
 
 1.562 
 
 1.526 
 
 1.491 
 
 1.457 
 
 1.426 
 
 1.396 
 
 1.366 
 
 1.338 
 
 1.312 
 
 1.286 
 
 1.261 
 
 1.237 
 
 1,280 
 
 1.612 
 
 1.574 
 
 1.538 
 
 1 502 
 
 1.469 
 
 1.437 
 
 1.407 
 
 1.377 
 
 1.348 
 
 1.322 
 
 1.296 
 
 1.271 
 
 1.247 
 
 
 1.625 
 
 1.586 
 
 1.549 
 
 1.514 
 
 1,480 
 
 1.448 
 
 1,417 
 
 1.387 
 
 1.359 
 
 1.332 
 
 1.306 
 
 1.280 
 
 1.256 
 
98 
 
 TABLE VII. For reducing observations, etc. Continued. 
 
 a 
 
 Temperature of external air degrees Fahrenheit. 
 
 ii 
 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 5 
 
 20 
 
 10 
 
 
 
 10 
 
 20 1 30 
 
 40 
 
 50 
 
 60 
 
 70 
 
 80 
 
 90 
 
 100 
 
 H 
 
 
 
 
 
 1 
 
 
 
 
 
 
 
 
 1,300 
 
 1.637 
 
 .598 
 
 1.561 
 
 1.525 
 
 1.491 
 
 .459 
 
 1.428 
 
 1.398 
 
 .369 
 
 1.342 
 
 1.316 
 
 .290 
 
 1.266 
 
 1 310 
 
 I.G49 
 
 .610 
 
 1.573 
 
 .536 
 
 1.502 
 
 .470 
 
 1 439 
 
 1.408 
 
 .379 
 
 1.352 
 
 1. 326 
 
 .300 
 
 1.275 
 
 1,320 
 
 1.661 
 
 .622 
 
 1.584 
 
 .548 
 
 1.513 
 
 .481 
 
 1.449 
 
 1.419 
 
 .390 
 
 1.362 
 
 1.336 
 
 .309 
 
 1.285 
 
 1, 330 
 
 1.674 
 
 .634 
 
 1.596 
 
 .559 
 
 1.525 
 
 .492 
 
 1.460 
 
 1.429 
 
 .400 
 
 1.372 
 
 1.346 
 
 .319 
 
 1.294 
 
 1,340 
 
 1.686 
 
 .646 
 
 1.608 
 
 .571 
 
 1.536 
 
 .503 
 
 1.471 
 
 1.440 
 
 .410 
 
 1.382 
 
 1.356 
 
 .329 
 
 1.304 
 
 1,350 
 
 1.698 
 
 .658 
 
 1.620 
 
 .582 
 
 1.547 
 
 1.514 
 
 1.482 
 
 1.450 
 
 .420 
 
 1.393 
 
 1.366 
 
 .339 
 
 1.313 
 
 1,360 
 
 1.710 
 
 .669 
 
 1. 631 
 
 .593 
 
 1.558 
 
 1.524 
 
 1. 492 
 
 1.461 
 
 .431 
 
 1.403 
 
 1.375 
 
 .348 
 
 1.323 
 
 1,370 
 
 1.722 
 
 .681 
 
 1.643 
 
 .605 
 
 1.569 
 
 1.535 
 
 1.503 
 
 1.471 
 
 .441 
 
 1.413 
 
 1.385 
 
 .358 
 
 1.332 
 
 1,380 
 
 1.735 
 
 .693 
 
 1.655 
 
 .616 
 
 1.581 
 
 1.546 
 
 1.514 
 
 1.482 
 
 .451 
 
 1.423 
 
 1.395 
 
 .368 
 
 1.342 
 
 1,390 
 
 1.747 
 
 .705 
 
 1.666 
 
 .628 
 
 1.592 
 
 1.557 
 
 1.524 
 
 1.492 
 
 .462 
 
 1.433 
 
 1.405 
 
 .377 
 
 1.351 
 
 1,400 
 
 1.759 
 
 .717 
 
 1.678 
 
 .639 
 
 1.603 
 
 1.568 
 
 1.535 
 
 1.503 
 
 .472 
 
 1.443 
 
 1.415 
 
 .387 
 
 1.361 
 
 1,410 
 
 1.771 
 
 .729 
 
 1.690 
 
 .650 
 
 1.614 
 
 1.579 
 
 1.546 
 
 1.513 
 
 .482 
 
 1.453 
 
 1.425 
 
 .397 
 
 1.370 
 
 1,420 
 
 1.783 
 
 .741 
 
 1.701 
 
 .662 
 
 1.625 
 
 1.590 
 
 1.556 
 
 1. 524 
 
 .492 
 
 1.463 
 
 1.435 
 
 .406 
 
 .380 
 
 1,430 
 
 1.796 
 
 .753 
 
 1.713 
 
 .673 
 
 1.636 
 
 1.601 
 
 1.567 
 
 1.534 
 
 .503 
 
 1.473 
 
 1.444 
 
 .416 
 
 .389 
 
 1,440 
 
 1.808 
 
 1.765 
 
 1.724 
 
 .685 
 
 1.647 
 
 1.612 
 
 1.577 
 
 1.545 
 
 .513 
 
 1.483 
 
 1.454 
 
 .426 
 
 .399 
 
 ,450 
 
 1. 820 
 
 1.777 
 
 1.736 
 
 ,696 
 
 1.658 
 
 1.623 
 
 1.588 
 
 1.555 
 
 .523 
 
 1.493 
 
 1.464 
 
 1.436 
 
 .408 
 
 ,460 
 
 1.832 
 
 1.788 
 
 1.748 
 
 .707 
 
 1.670 
 
 1.633 
 
 1.599 
 
 1.565 
 
 .533 
 
 1.503 
 
 1.474 
 
 1.445 
 
 .418 
 
 ,470 
 
 1.844 
 
 1.800 
 
 1.759 
 
 .719 
 
 1.681 
 
 1.644 
 
 1.609 
 
 1.576 
 
 .543 
 
 1.513 
 
 1.484 
 
 1.455 
 
 .427 
 
 ,480 
 
 1.857 
 
 1.812 
 
 1.771 
 
 .730 
 
 1.692 
 
 1.655 
 
 1.620 
 
 1.586 
 
 .554 
 
 1.523 
 
 1.493 
 
 1.465 
 
 1.437 
 
 ,490 
 
 1.869 
 
 1.824 
 
 1.782 
 
 1.742 
 
 1.703 
 
 1.666 
 
 1.630 
 
 1.597 
 
 .564 
 
 1.533 
 
 1.503 
 
 1.474 
 
 1.446 
 
 1,500 
 
 1.881 
 
 1.836 
 
 1.794 
 
 1.753 
 
 1.714 
 
 1.677 
 
 1.641 
 
 1.607 
 
 1.574 
 
 1.543 
 
 1.513 
 
 1.484 
 
 1.45C 
 
ITsTOEX. 
 
 Page. 
 
 Anemometer 51 
 
 Anemometer correction 52 
 
 Aneroid barometer 41 
 
 Application form for voluntary observers 11 
 
 Auroras, instructions for observing 61 
 
 Barometer, aneroid 41 
 
 changes of aneroid , 42 
 
 mercurial .' 30 
 
 cistern of 36 
 
 correction of observations 38 
 
 placing of 31 
 
 observation of : 32 
 
 reduction of observations to sea-level 96 
 
 reduction of reading to 32 94 
 
 reduction to sea-level 39 
 
 Beaufort scale 53 
 
 Bench-mark 59 
 
 Climate, general phenomena of 66 
 
 Clouds, classification 55 
 
 estimates of cloudiness 56 
 
 movement of 57 
 
 Coronse 60 
 
 Dew point 27 
 
 tables for 71 
 
 Directions, special, to observers -.. 67 
 
 Earthquakes 64 
 
 Evaporation 57 
 
 E vaporometer, Piche 58 
 
 Frost 60 
 
 Hygrometer, hair 30 
 
 Hypsometer 42 
 
 Instructions for use of tables 69 
 
 Maximum thermometer 18 
 
 error of 18 
 
 setting of 20 
 
 Marks on thermometer, replacing of 26 
 
 Mean temperature 24 
 
 Minimum thermometer 15 
 
 method of uniting column J6 
 
 placing thermometer 20 
 
 setting index 18 
 
 Percolation gauge 49 
 
 Piche evaporometer 58 
 
 9377 7 99 
 
100 
 
 " ,.-* o - L ^ t ^ Page. 
 
 Psychromet^ ^ Ai". L C .C.. J"...-i.'.^t!L^. c 28 
 
 whirling of 29 
 
 wetting of muslin 29 
 
 Radiation thermometer, solar 25 
 
 Rainfall measurement 46 
 
 Rain gauge 43 
 
 instructions for use 44 
 
 support for 46 
 
 Relative humidity 28 
 
 tables for 81 
 
 River gauge 58 
 
 Sand spouts 61 
 
 Snowfall measurement 48 
 
 Tables, instructions for use of. 69 
 
 Thermometers 12 
 
 correction of 13 
 
 fall of freezing-point 14 
 
 maximum 18 
 
 minimum 15 
 
 packing for transportation 21 
 
 removal of air from column 14 
 
 replacing of marks 26 
 
 rise of freezing-point 13 
 
 shelter for 22 
 
 solar radiation 25 
 
 Thermoscope . . . ; 26 
 
 Thunderstorm 61 
 
 Tornadoes ; 61 
 
 Vapor of water in air 27 
 
 table of correction to pressure for reading of barometer 91 
 
 table of grains of vapor in cubic foot of air 93 
 
 table of pressure in inches 93 
 
 table of weight of vapor in air 93' 
 
 Weather, state of 60 
 
 Wind-vane 49 
 
 Vernier . . 25 
 
 LIST OF TABLES. 
 
 Table I. Dew point from wet and dry thermometer readings 71 
 
 II. Relative humidity , 81 
 
 III. Correction to vapor pressure for reading of barometer 91 
 
 IV. Vapor pressure in inches 92 
 
 V. Grains of water vapor in a cubic foot of air 93 
 
 VI. Reduction of barometer reading to 32 94 
 
 VII. Reduction of observations of barometer to sea-level 96 
 
THIS BOOK IS DUE ON THE LAST DATE 
 STAMPED BELOW 
 
 AN INITIAL FINE OF 25 CENTS 
 
 WILL BE ASSESSED FOR FAILURE TO RETURN 
 THIS BOOK ON THE DATE DUE. THE PENALTY 
 WILL INCREASE TO 5O CENTS ON THE FOURTH 
 DAY AND TO $1.OO ON THE SEVENTH DAY 
 OVERDUE. 
 
 
Gaylamount 
 Pamphlet 
 
 Binder 
 Gaylord Bros., Inc. 
 
 Stockton, Calif. 
 T. M. Reg. U.S. Pat. Off. 
 
 417958 
 U- 
 
 UNIVERSITY OF CALIFORNIA LIBRARY