410 
POPULAE SCIENCE EEVIEW. 
discovery be included in the arrangement of the series of 
observations. It remains to mention that the arrangements 
must also include that every instrument be screwed down to 
the table or framework_, so that no lurching of the balloon_, 
no vibration of the car from droppiug the grapnel,, and no 
accident^ can displace them; everything else must be tied 
with rope of sufficient length for use and safe when out of 
use ; for instance,, the lens^ which comes into active use when 
at high elevations^ where the eye loses some of its power,, 
must be fixed to cordage near the right hand with string of 
sufficient length that it can be directed to any instrument; 
in fact^ every instrument must be screwed down if to be kept 
fikm^ and everything else tied^ and all so arranged as to be 
readily removeable. 
The object of this communication is to give the reader a 
sketch of the operations in balloons for such investigations ; 
the nature and arrangement of the instruments used, and 
some of the results found. It is not the object, nor would the 
allotted space admit, to speak at all upon the management of 
balloons, with which, indeed, I had nothing to do further than 
indicating when to control the rate of ascending or descending 
in each stratum, so that the instruments might have sufficient 
time to take up true readings. 
In speaking of the results obtained, it will be convenient 
to keep each subject of investigation separate, and first I shall 
speak of the Decline of Temperature. 
In every ascent the series of observed temperatures, when 
compared with the calculated temperatures at the rate of 
1° decrease for every 300 feet, were found to be very different, 
and that these differences, with different ascents, when com- 
pared, did not agree. The most marked differences, in 
this respect, were found dependent on the state of the sky, 
which exercised a great influence, and the experiments had to 
be divided into two groups, one with clear or nearly clear 
skies, and the other with cloudy skies ; the dechne of tem- 
perature being the more rapid with skies free from cloud. 
I will flrst speak of the results with cloudy skies as based 
upon all the experiments under those circumstances. 
At 1,000 feet high the dechne was 44°; in the second and 
third thousand there was a further dechne, a httle more than 
34 ° in each thousand feet; this amount decreased to 3^ between 
5,500 and 6,500 feet, and was less and less in each successive 
1.000 feet, thl it was as smah as 1° in this space at about 
21.000 feet high. 
Therefore, an average space of 223 feet was passed for a 
dechne of 1° up to the first 1,000 feet, this space becoming 
greater, till at an elevation of 21,000 feet, the sky being stiU 
