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(twenty kilometers and more), tlie inainied Inillooii, in whicli the panillel 

 observations were made, had to rise as high as possible. It was 

 planned to go as liigh as ten kilometers and reached even a height of 

 nearly eleven. 



It is easy to see that expeditions to such a height cannot be free 

 from danger, if we thiiüv of the atmospheric pressure of ± 200 mM 

 and of the temperature to below — 40 "C, which have been observed 

 at these heights. The homage then, which the committee wish to 

 be paid to Berson, applies partly to the courage and the intrepidity, 

 with which this explorer has frequently risked his life in behalf of 

 the uncommon task, which he imposed upon himself in the service 

 of science. 



The whole work, published in 1899/1900, consists of three big 

 quarto volumes. The first of these is partly devoted to an historical 

 and critical survey of the development of scientific aerial voyages, 

 partly also it deals with the construction of balloons and instruments 

 and with the methods of obsei-vation and reduction. Moreover it 

 contains the data as to the tracks covered by the balloons and the 

 figures got by the observations. The second volume offers an ample 

 description of the separate aerial voyages. In the tliird the obser- 

 vations are sifted and discussed, being treated under ditfcrent heads 

 as: temperature of the air, moisture, formation of clouds, velocity 

 of wind, direction of wind, radiaton, atmospheric electricity. This 

 volume winds up with a chai)ter, written by von Bezold, and entitled: 

 "Theoretische Schlussbetrachtungen". 



Here we shovdd not omit mentioning the names of Baschin, BöiiN- 

 STEiN, Gross, Kremser, Stade and Süring, who have all of them 

 contributed to the composition of the great work and also personally 

 taken part in the scientific aerial voyages. 



A short survey of the provisional results of a more general tenor 

 must not be left aside here. 



1«' . Formerly it has sometimes been thought that the temperature 

 in the higher layers of the atmosphere approached a limit of — 35 

 to — 50^ C; these investigations however do not at all point to the 

 existence of such a limit. Temperatures also, considerably lower than 

 the above, have come to light. 



2'"l In the lower layers of the atmosphere the temperature, in 

 rising, diminishes on the whole less rapidly than would answer to 

 convective equilibrium. x\bove 4000 M, however, the rate of decrease 

 grows larger and seems to approach that value of nearly 1° C. per 

 100 meters as a limit. This is in keeping with a supposition of von 

 Bezold based on theoretical grounds, whilst the behaviour in lower 



