METEOROLOGICAL WORK 55 



loons, while the temperature has been determined at the prov- 

 ing grounds by sending self-recording instruments aloft in spe- 

 cially constructed box-kites, as well as by sending self-record- 

 ing instruments and meteorological observers aloft in airplanes. 

 It has been with the aid of observations of this sort that the 

 new range tables for the Ordnance Department of the United 

 States Army have been constructed. The importance of this 

 work may be understood when it is considered that these range 

 tables will be used in connection with the firing of all guns, and 

 errors in them would produce errors in the range of every gun 

 fired with their aid. 



3. The Development of Long Range Propaganda Balloons. 

 In view of the fact that above an altitude of 10,000 feet 95 

 per cent, of the winds both over western Europe and over the 

 United States blow from west to east (i. e., have a westerly 

 component), Captain Sherry in 1917 suggested the development 

 of a large program for the extension of the use of pilot bal- 

 loons for the purpose of flooding the whole of Germany and 

 Austria with propaganda dropped from such balloons. The 

 project was submitted to the meteorological and military 

 agencies in France and pronounced infeasible, chiefly because 

 the rapid diffusion of hydrogen through rubber had hereto- 

 fore rendered it impossible to obtain pilot balloon flights of 

 more than about 100 miles. Undiscouraged, however, by these 

 reports, Mr. W. J. Lester, Dr. S. R. Williams and Sergeant 

 Redman attacked the problem of extending the range of pilot 

 balloon flights by developing an automatic ballast-control and 

 by reducing the diffusion by means of a special dope. 



The automatic control was ingeniously simple, its essential 

 feature being a belly band which kept the girth of the balloon 

 constant (at a diameter of four feet) through the discharge, 

 in the act of shrinking, of a few drops of kerosene, thus causing 

 reascension and consequent expansion. 



With this device the balloon not only does not fall but rises 

 very gradually to higher and higher levels until its ballast of 

 kerosene or alcohol is exhausted. 



