302 EXPLORATIONS - OF THE UPPER ATMOSPHERE. 



The danger of these high altitudes is well known, especially since 

 the dramatic ascent of the balloon Zenith; hence it seemed wholly 

 desirable, in view of the progress that has been made in the construc- 

 tion of automatic registering apparatus, that unmounted aerostats car- 

 rying these improved instruments should be used. Thus there would 

 be no risk to the lives of the observers, and the difficulties of ascents 

 to great heights, requiring balloons of enormous capacity, would be 

 much diminished. 



We owe to M. Gustave Hermite the first experiments of this kind, 

 these being first made by means of recording balloons formed of paper, 

 then by an "Aerophile," made entirely of gold-beater's skin, having a 

 capacity of about 113 cubic meters. The first ascent was from the 

 aerostatic park of Vaugirard, March 21, 1892, when the height attained 

 was 16,000 meters, but the tracing made was incomplete, the ink of the 

 registering pen having frozen because of the excessive cold of the 

 upper regions. Many other experiments were afterwards made during 

 succeeding years, and in each of them some new improvement was 

 effected. 



In Germany, M. Assmann, chief of section in the Meteorological Insti- 

 tute at Berlin, under the direction of M. von Bezold, had a balloon 

 of 250 cubic meters capacity built, which, released on two different 

 occasions, reached heights of 16,600 and 18,000 meters, and fell the 

 first time in Eussia, the second time in Bosnia. 



M. Besangon, the young and already celebrated aeronaut, having 

 combined his efforts with those of M. Hermite, there resulted from the 

 collaboration of these two investigators great improvements in all 

 parts of the apjjaratus hitherto used. Considering that the essential 

 condition for reaching higher and higher altitudes consisted in pro- 

 gressively increasing the ratio between the ascensional force and the 

 volume of the balloon, the weight of every part of their new aerophile 

 was reduced to a minimum. The tissue employed for the envelope was 

 a marvel of lightness and strength. Its resistance to traction was 550 

 kilograms per linear meter, its weight 30 grams per square meter when 

 unfinished, and 120 grams after it was made impermeable by four suc- 

 cessive coats of varnish. The volume of the balloon being 380 cubic 

 meters, its envelope, therefore, weighed 9 kilograms before varnishing, 

 and 31 kilograms after the last coat of varnish had been applied, the 

 total varnished surface being 250 square meters, l^ow, the weight of 

 the same volume and surface made of cotton or silk, having a lifting 

 power of 1,000 kilograms per meter, is about 110 kilograms. We per- 

 ceive at once what progress was made in the construction of this bal- 

 loon without in any way sacrificing its strength. 



This balloon was provided at its upper extremity with a valve of 

 discharge, having a diameter of 48 centimeters, acting automatically 

 to produce descent, and effecting collapse in a few moments. It was 

 covered by a net of white Anjou hemp, of exceptional strength in 



