October 27, 1922] 



SCIENCE 



483 



United States, and to summarize and publish 

 the aeeumulated data at sucli intervals as seem 

 convenient. In this way, we need not sit idly 

 awaiting that golden day when we maj' trace 

 upon the daily chart the coursing of the air 

 streams above our country, bu't may study the 

 results of observations thus far obtained. 



The Aerologi«al Division of the Weather 

 Bureau, Mr. W. E. Gregg in charge, has re- 

 cently summarized and published the results of 

 observations at the several kite stations of the 

 "Weather Bureau, under the title "An Aerolog- 

 ieal Survey of the United States, Part I. Ke- 

 sults of observations by means of kites. ^ 



In addition to the summarizing of data, ' a 

 useful contribution has been made in the por- 

 tion dealing with the "standard atmosphere." 

 The "standard atmosphere" is a term which has 

 come into general use among aeronautical 

 engineers and artillerists, and denotes the gen- 

 eral or average condition of the atmosphere 

 with respect to temperature, pressure, and 

 density, to as great heights as are employed in 

 the several fields. As far as aviation is con- 

 cerned, there is a relatively large amount of 

 data available for ithe maximum height at 

 which flying is likely to occur, but the great 

 maximum ordinates employed in ballistics re- 

 quire a knowledge of conditions to much 

 greater heights. 



It is true that at no time does the standard 

 atmosphere exist, but it does afford at all times 

 a standard from which the departures will be 

 quite small. Several plans have been offered 

 in various countries to satisfy ithe need for 

 such an average atmosphere, as, for example, 



1 Monthly Weather Review Supplement No. SO. 

 Copies of this Supplement may be obtained from 

 the superintendent of documents. Government 

 Printing Office, Washington, D. C, at 25 cents 

 each. Mr. Gregg has made a very full abstract 

 of this work and published it in the Monthly 

 Weather Review for May, 1922. Eeprints of this 

 abstract may be obtained gratis upon application 

 to the chief of the Weather Bureau, Washington, 

 D. G. It is believed that this abstract will sat- 

 isfy the needs of all those who have an academic 

 or popular interest in the work. Many of the 

 cliarts are reproduced, but the tables are omitted 

 and the discussion of the standard atmosphere i;; 

 very much condensed. 



the "isothermal atmosphere." But, owing to 

 the dependence of atmospheric pressure and 

 density upon the vertical distribution of tem- 

 perature, and the im,portance of the tempera- 

 ture factor in power production calculations 

 with reference to air-craft engines, as well as 

 in the design of air-craft instruments, it has 

 been thought best to base the standard atmos- 

 phere upon the standard lapse rate of tem- 

 perature. 



Up to 10 kilometers, Toussaint's formula, 

 T — 15 — 0.0065Z, 

 in which I is the temperature in degrees. Cen- 

 tigrade, and Z the altitude in meters, holds for 

 the mean annual values, and is very satisfac- 

 tory, providing, as Mr. Gregg says, "one set 

 is deemed sirOicient for use throughout the 

 year." This formula has been adopted in 

 France, Italj' and England. Where values are 

 needed for both winter and summer, new tables 

 have been provided which will be more satis- 

 factory than Toussaint's formula. 



It happens that the aeronautical research 

 stations and artillery proving grounds of the 

 army and navy are all within three degrees of 

 latitude 40° N. Moreover, three of the 

 Weather Bureau kite stations are equally close 

 to this parallel, and from these three stations, 

 means have been computed up to five kilo- 

 meters. Above five kilometers, sounding bal- 

 loon data obtained at St. Louis (1904-19'07) 

 and at Tort Omaha (1911 and 1914) have 

 been used. From the base of the stratosphere 

 (about twelve kilometers) up to twenty kilo- 

 meters, the greatest altitude considered, a con- 

 stant temperature of — 55° C. has been used. 

 The pressures for the various levels were then 

 computed by means of the hypsometric for- 

 mula, making proper allowance for the water 

 vapor content of the air and the vairiation of 

 gravity with altitude and latitude. 



The discussion of the standard atmosphere 

 appears in both the Aerological Survey and in 

 Report No. 147 of the National Advisory Com- 

 mittee for Aeronautics,- the latter being in 



- Gregg, Willis Eay : ' ' Standard Atmosphere. ' ' 

 11 pp., 4 figs., 6 tables. Copies may be obtained 

 from the Superintendent of Documents, Govern- 

 ment Printing Office, Washington, D. C, at five 

 cents each. 



