W. LE CONTE STEVENS. 41 
Aside from the observations made by Charles during 
his first and only ascent, no use of the balloon was made 
for ‘Scientific purposes until after the beginning of the 
present century. In 1804, Gay Lussac ascended from 
Paris to a height of more than four miles, where he 
found clouds still overhead. He brought back speci- 
mens of air for analysis, which proved to consist of the 
same ingredients, in the same proportions, as that at the 
surface. In 1850, Bixio and Barral repeated Gay Lus- 
sac’s experiment, and with the same result. They ex- 
perienced sudden and unexpected changes of temper- 
ature, the thermometer falling from + 15° F., at twenty 
thousand feet, to — 38° F., at twenty-three thousand 
feet. 
In 1861, a committee was appointed by the British As- 
sociation, and an appropriation made to defray the ex- 
pense of making a systematic examination of the upper 
atmosphere by the use of the balloon. The actual work 
of the committee was done chiefly by Mr. James Glai- 
sher, who made twenty-eight ascents between 1861 and 
1867. In that of September 5, 1862, he reached a height 
estimated to be thirty-seven thousand feet, incurring 
great peril in consequence of the extreme cold and the 
diminished density of the air. He made many obser- 
vations of great value, which were duly published in his 
report to the Association. 
During the early days of ballooning many futile at- 
tempts were made to propel and direct the aerostat. In- 
deed prior to 1852, balloon sailing was only aerial drift- 
ing, and not aerial navigation. Aerostatics was suf- 
ficiently understood, but aeronautics was still beyond 
human power. Meanwhile important changes had been 
made in ocean navigation as a result of the introduction 
of steam as a motive power for the driving, first of 
paddle wheels and afterward of screw propellers. In 
1852, Giffard, a young French engineer, constructed an 
