404 
POPULAE SCIENCE EEVIEW. 
steps they were again compelled to halt to recover breath, and 
thus toiling at last the summit was reached. 
On arrival here, the keenest impression was one of joy at 
the cessation of labour and great anxiety ; for the prolonged 
struggle, and the recollection of the sufferings this victory 
had cost, says De Saussure, produced rather a feeling of 
irritation, and he stamped his foot, he says, more with a 
sensation of anger than pleasure. His object was not only to 
reach the crown of the mountain, but to make such observa- 
tions and experiments there as would alone give any value to 
the enterprise, and he began to be afraid lest he should fail in 
his intentions in this respect. He had already found out, even 
at a much lower elevation, that every careful observation in 
such an attenuated atmosphere was fatiguing, on account of 
the necessity of holding the breath whilst thus engaged ; and 
as the tenuity of the air at this elevation necessitated increased 
frequency of respiration, this suspended breathing caused De 
Saussure a sensible feeling of uneasiness, and he found himself 
compelled to rest and pant after each careful observation as 
after having mounted one of the steepest slopes. 
Four hours were thus spent on the top of the mountain, 
three hours and a half being devoted to observations and 
experiments on the summit, when the party began to descend. 
They passed the night (the third since they left Chamouni) 
on Les Mulets, and De Saussure writes : — 
At the moment of my reaching the summit I did not feel satisfied ; I was 
less so when I left it. I only reflected then on what I had not done. But, 
in the stillness of the night, after having recovered from my fatigue, when I 
went over the observations I had made, I enjoyed a true and unalloyed 
satisfaction. 
The simple narrative of this eminent man is throughout a 
commentary upon the use of a balloon for the purpose of - ex- 
ploring the higher regions of the atmosphere. This ascent — 
the one great fact of De Saussure^s life, the accomplishment 
of the wish of twenty- seven years — to what did it tend ? Of 
what value to science is one isolated day^s experience ? What 
can a single set of observations amount to, except to appease 
curiosity ? Up to this time, however, all our knowledge of 
the physical state of the upper atmosphere was based upon 
the observations which for ages had been made on mountain 
sides, yielding results always differing from each other ; and, 
up to the time of the balloon, we had no means of ascending 
into the air at all to test the conditions of the atmosphere 
apart from the terrestrial influences and the inevitable labour 
of ascending the mountain's side. The results thus found 
were of necessity disconnected ; for the time occupied between 
