42 J. P. Cooke—Buoyancy of the Atmosphere. 
caused by the radiation of the body while weighing, followed 
only after some time by a rise of the very sensitive thermometer 
mployed, and this effect was obtained in weighing a vessel 
which displaced only about 75 cubic centimeters of air. 
Second Series. 
No. 1883 Weight. OF bak H. reduced. Result. 
1 May 29 T3447 23°6 2971'S 3011 451 
2 May 30 87°3432 23.2 302°0 305°8 87°3451 
K 87°3437 24°5 301°8 304°3 87°3451 
4 May 31 87°3444 23°8 298°8 302°0 87:3450 
5 une 87°3429 2°8 302°4 306°6 87°3450 
6 June l 87°3432 23°75 302'4 305°65 87°3450 
7 June 2 87°3419 305'°2 9°6 873451 
8 June 3 873420 21°95 304'5. 309°55 87°3450 
9 June 3 87°3427 23°16 303°8 307°6 87°2451 
10 June 4 87°3441 3011 Sue's 8773451 
di dune. 6 7344 26°0 304 302°4 87°346] 
12° June's 7-344 26°3 300°6 3801°3 87°3450 
13 une 6 87°34435 25°55 300°75 302°2 87°3451 
14 June 7 87°3452 26°7 > 299°0 299°3 87°3450 
15 June 8 87°3464 29°4 297°9 295°5 87:3450: 
Greatest weight, 87°3464 Barometer, 295°5 
Smallest weight, 87°3419 . 309°6 
Differences, 45 14°1 
Constant = 4°65 m. g.+14°1 = 0°319 m. g.* 
The limits in the accuracy of the method here described are 
obvious; but it will be noticed that the accuracy of the method 
is exactly proportional to the requirement. The greater the 
volume of the load, and hence the greater the effect of uoy- 
ancy, the more Bee can the Semana be found, 2 
load is large it becomes necessary to measure the temperature 
and pressure with great precision, and to protect the balance 
from radiation and from all causes of rapid change of tempera- 
ture. It was a great satisfaction to ihe writer to find that by 
so simple means the panels weight of glass vessels of consid- 
erable size may be determined with accuracy to the tenth of a 
milligram, an secitracy a is fully equal to that of the 
* In combining Bie the extreme weights we must obviously take nok that 
neither of them is a affected by any gagrses Sle rors; and a e cer- 
tain value of the constant would ae obtained ates ing all the observations 
after well known naked ‘his complication Bronte is seldom necessary. a 
a — hang render the final coailie irregular, and lead to a rediscussion of 
observ: 
