1866.] Tableau of High Asia. 67 



height of 10,374 ft. The well known English Professors Tyndall and 

 Prankland even passed the night of August 21st, 1859, on the top of 

 the Mont Blanc (15,784 ft.) 



2. Balloon-ascents. 



In the free atmosphere the greatest height was reached by Mr. 

 Glaisher in a balloon, which was directed by Mr. Cos well ; he ascend- 

 ed, September 5th, 1862, the extraordinary height of at least 30,000 ft., 

 but, as he was unable to make any observations above that height, 

 being suddenly overtaken by sickness, it is supposed that the balloon 

 rose as high as seven miles = 36,960 ft. 



Not less remarkable than this ascent was the one performed by 

 Gay-Lussac, as early as the beginning of this century (September 

 16th, 1804), when he rose to 23,020 ft, Between Gay-Lussac's and 

 Mr. Glaisher's ascent, several attempts have been made to reach great 

 heights in balloons, especially in England, during one of which the 

 late Mr. Welsh reached (November 10th, 1852) 22,930 ft.* The bal- 

 loon-ascents made in England were all combined with experiments of 

 a highly interesting nature, and instituted by a scientific committee, 

 among whose members it is sufficient only to name Sabine and Sykes. 



Previous to Mr. Welsh, Messrs. Bixio and Barral rose (July 27th, 

 1850) to a height of 23,009 ft. 



As a balloon-ascent, remarkable not only on account of the height 

 reached, but on account of the horizontal distance performed, I must 

 mention the one made by Mr. Nadar, in company with eight persons, 

 October 18th, 1863. Mr. Nadar rose from Paris and let himself down 

 — or he rather fell down — near Rethem, a small town on the river 

 Aller, in Hanover. The direct distance between these two towns is 

 about 395 miles, and as it took 15 hours, 47 minutes to travel 

 through this distance, the balloon flew 2,227 ft per minute, or 37 ft. 

 per second. But, as the balloon was far from going in a straight line, 

 it has been computed, that the greatest velocity attained by it 

 amounted to 50 ft. per second. 



3. Effect of height. 



The effect of height is chiefly perceptible in the decrease of tem- 

 perature and barometrical pressure. According to our observations, 

 * " Philosophical Transactions," 1853, Part III., p. 320. 



