BALLOON ASCENTS. 
417 
better defined and more distinct. The line H,.as seen from the 
earth as nebulous, was seen as made up of fine parallel lines; 
and generally the spectrum was longer, the lines more numer- 
ous, the colours brighter, as seen at a high elevation, than 
when viewed from the earth. 
Let me now briefly refer to a few facts connected with the 
wind. Firstly, to the currents in the atmosphere. These were 
found to be very different, and a good deal of information was 
collected in relation to them, in the twenty-five different 
ascents : in all it was found that the velocity at the earth^s 
surface was very much less than at high elevations. 
The aneroid barometers at first failed, an inch graduated 
on the dial plate was not an inch, but ultimately the results 
were as good as those by the mercurial barometers. Of the seve- 
ral hygrometrical instruments, there was very little difference in 
the results, as found by different instruments, and then the dry- 
and wet-bulb therm ometer is found to be a perfectly trustworthy 
instrument up to considerable heights. A magnet was found 
to occupy a little longer time in vibration when high up than 
on the earth, and therefore magnetism was slightly less in 
intensity. 
The results which have been obtained by the balloon ascents 
already made, give us a good deal of information upon points 
in which we could gain none by any other means. Those made 
upon the decline of temperatures instruct us that we must 
again investigate the laws of refraction,' and they indicate that 
the laws of refraction good at one place may not be good at 
another ; for we may infer that the state of things existing at 
different observatories, differing the one from the other so 
greatly, may require a special determination of the laws of 
refracLon,' as applicable to those different states. 
The subjects of investigation which may be pursued in. 
balloons are very varied ; they are so conducive to the good of 
science, as to be of the first importance. Still, this country, 
from its variation in climate, its small extent, and the 
consequent great uneasiness of mind of the observer, when 
above the clouds, and out of sight of the earth, not knowing 
or having any means of judging of the velocity of his motion, 
being equally insensible whether he is moving at ten miles or 
seventy miles an hour ; and whether or not he is then over 
the sea ; that this country is not well suited for these experi- 
ments, and, perhaps, not the best for determining the laws 
which govern atmospheric changes. 
I am in hopes that similar researches will be made in France, 
and, I hope, in other countries. It is probable that the large 
plains of the continent, where the weather is more uniform, and 
the land of greater extent, that the experiments can be made 
