86o Handbook of 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 

 1860. 



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

 doubtless, have resulted in such an organization in the United States in the 

 early 6o's, had not the Civil War intervened, absorbing public 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 10, 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 Hill 

 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. 



