86o Handbook oj Nature-Study 



This report created a profound impression among scientific men and 

 active measures were taken at once that resulted in the organization of 

 weather services in the principal countries of Europe between 1855 and 

 i860. 



The work of Professor Henry, Abbe, and others in this country would, 

 doubtless, have resulted in such an organization in the United States in th:; 

 early 6o's, had not the Civil War intervened, absorbing pubhc attention to 

 the exclusion of other matters. It was not until 1870, that Dr. Increase A. 

 Lapham of Milwaukee, in conjunction with Representative Paine of that 

 city, was able so to present the claims for a national weather service that 

 the act was finally passed that gave birth to the present meteorological 

 bureau in the United States. Dr. Lapham issued from Chicago on Novem- 

 ber ID, 1871, the first official forecast of the weather made in this country. 



The Atmosphere 



What is known about the atmosphere of our 



earth has been learned from the exploration of 



a comparatively thin layer at the bottom. 



There is reason to believe that the atmosphere 



extends upwards about two hundred miles from 



the surface of the earth. We have a great mass 



of observations made at the surface, some on 



mountains, but few in the free air more than 



a few miles above the surface. Our knowledge 



of the upper atmosphere is, therefore, in the 



Snow crystal. nature of conclusions drawn from such obser- 



Photomicrograph by vations as are at hand, and is subject to changes 



w. A. Bentiey. and modifications as the facts become known 



by actual observation. 



During the past few years a concerted effort has been made in various 



parts of the world to explore the upper atmosphere by means of kites and 



balloons, carrying meteorological instruments that automatically record 



the temperature, pressure, humidity, velocity and direction of the wind, etc. 



In this country this work has been carried on principally at the Mount 



Weather Observatory, which is located in Loudon County, Virginia, and is 



under the direction of the United States Weather Bureau and at Blue HiU 



Observatory, a private institution located near Boston and supported by 



Professor Lawrence Rotch. From observations thus obtained much has 



been learned about the upper atmosphere that was not even suspected 



before. Some theories have been confirmed and some destroyed, but this 



line of research is gradually bringing us nearer the truth. 



Air as a Gas 

 Air is not a simple substance, as was once supposed, but is composed of 

 a number of gases, each one of which tends to form an atmosphere of its 

 own, just as it would if none of the other gases were present. The different 

 gases of the atmosphere are not chemically combined but are very 

 thoroughly mixed, as one might mix sugar and salt. Samples of air col- 

 lected from all parts of the world show that the relative proportion of the 

 gases forming the atmosphere is practically uniform. 



