MOUNTAIN OBSERVATORIES IN AMERICA AND EUROPE. 69 



Among those directly affecting astronomical observations are the fol- 

 lowing : 



(1) The rate of the diminution of temperature with altitude and the 

 laws which govern it. The lowest temperature registered by Barral 

 and Bixio (1850) was - 39°.7 C. {= - 39°.5 R) at 7000 metres 

 {= 22,966 feet). Gross and Berson (1894) found a slightly higher tem- 

 perature (- 86°. 5 0.) at the altitude of 7700 metres (= 25,262 feet). A 

 balloon carrying self-registering apparatus (but no observer), dispatched 

 by Hermite (1893), recorded - 55° C. {= 58.9 F) at 14,000 metres 

 (45.932 feet) ; and a similar balloon, sent by Gross and Berson from 

 Berlin (1894), registered - 67° C. (- 88°.6 F) at about 18,500 metres 

 (60.696 feet; 11.5 miles). 



(2) The laws of the distribution of moisture in the atmosphere. 



( 3) The velocity of the winds of the upper air. The motion of the 

 balloon last spoken of was about 33 metres (108.3 feet) per second. 



(4) The pressure of the atmosphere. 



(5) The physiological effects of increased altitude in balloon ascen- 

 sions (which are made without marked physical exertions on the part 

 of the observer, though not without mental anxiety, probably) have 

 some bearing on the question of life and work at high mountain- 

 .stations. 



From 3000 to 4000 metres (9842 to 13,123 feet) Biot and Gay- 

 Lussac found the pulse-rate increased by some thirty per cent. Above 

 5000 metres (16,404 feet) difficulty of breathing and a desire to sleep 

 are manifested. At 8000 metres (26,247 feet) Tissandier (1875) fell 

 ill a swoon, and when he awoke he found his two companions (Sivel 

 and Croce-Spinelli) dead beside him. 



The purely meteorological data to be acquired by balloon ascents 

 need not be recited here, though they are of the first importance. Dr. 

 Solincke j^oints them out (in an address delivered before the Royal 

 Academy of Sciences at Munich) in detail, in connection with a 

 brief sketch of the history of the development of our knowledge of 

 the laws of the winds — a capital question. While much is known 

 froiii pure mathematical and physical theory, from thousands upon 

 thousands of observations at ordinary levels, and from very many at 

 inoiiiitain-stations, this fundamental problem is not yet solved. In 

 Dr. Sohncke's words, meteoroloji-v is at a standstill. The elevated 

 stations on peaks have given much valuable information, but their 

 data for the upper air are affected by the local topography and by the 

 suri-ouuding ground. TIk,' Eiffel tower is, in its way, an ideal high 

 station, though its height is not sufficient. 



In order to make further jjrogress, I'ecourse must be had to balloons 

 — both with and without observers. 



