45G 
AEKOSTATION. 
situated, taken some refreshment, they ascended higher, viz. till the 
barometer fell to 122 inches : and at that height the cold out of the 
car was insupportable, although the thermometer was now only one 
degree below the freezing point. Here our adventurers were obliged 
to respire very rapidly, and their pulsations became very quick. In 
this region, while the balloon was invisible to the earth, Mr. Robertson 
made the following experiments : 
1. Having let a drop of ether fall on a piece of glass, it evaporated 
in four seconds. 
2. He electrified by friction, glass and sealing wax ; but those sub- 
stances gave no signs of the accumulation of electric fluid, that could 
be communicated to other bodies. The Voltaic pile, which, when the 
balloon was set free from the eaVth, acted with its full force, gave 
only one-tenth part of the electricity. 
3. The dipping needle seemed to have lost its magnetic virtue, and 
could not be brought to that direction which it had at the surface 
of the earth. 
4. He struck with a hammer, oxygenated muriate of potash. The 
explosion occasioned a sharp noise, which, though not very strong, 
was insufferable to the ear. It is also to be observed, that though 
the aeronauts spoke very loudly, they could only with great difficulty 
hear each other. 
5. At this height Mr. Robertson was not able to extract any elec- 
tricity from the atmospheric electrimeter and condenser. 
6. In consequence of a suggestion from Professor Helmbstadt, of 
Berlin, Mr. Robertson carried wdth him two birds. The rarefaction 
of the air killed one of them, and the other was unable to fly ; it lay 
extended on its back, but fluttered with its wings. 
7. Water began to boil by means of a moderate degree of heat 
maintained with quick lime. 
8. According to observations made, it appeared that the clouds 
never rise above 2000 toises ; and it was only in ascending and 
descending through clouds, that Mr. Robertson was able to obtain 
positive electricity. 
The greatest height attained in this voyage is estimated at 2600 
toises. 
Mr. Robertson afterwards, viz. on the thirtieth of June, 1804, 
ascended from Petersburg with the academician Sacharof ; the 
aeronauts, taking with them, for the purpose of making the different 
experiments proposed by the academy, twelve exhausted flasks, a 
barometer, an attached thermometer, two electrometers, sealing wax, 
and sulphur, a compass and magnetic needle, a seconds watch, a bell, 
a speaking trumpet, a prism of crystal, and unslaked lime, and a few 
other apparatus for chemical and philosophical experiments. 
In order to ascertain, with some precision, over what part of the 
earth the balloon at any time was hovering, the two following methods 
were employed. 
In an aperture made in the bottom of the car, there was fixed, per- 
pendicularly, an achromatic telescope, which shewed very distinctly 
those terrestrial objects over which the balloon happened to be, and 
to which side it directed its course. In the next place, two sheets of 
