454 
MR. BAILY ON THE CORRECTION OP 
Twentieth set . — Results with the 2-inch cylinders placed at the end of the 
long brass rod. 
Thickness 
of the 
cylinders. 
No. 
n 
Weight of 
adhesive 
air. 
Weight due 
to cylinder 
alone. 
inch. 
0-00* 
43 
4-083 
1-484 
0-18 
81 
6-216 
3-590 
1-389 
0-50 
82 
4-046 
3-117 
1-628 
These results are somewhat greater than those deduced from experiments 
with the same cylinders in the 17th set; but here I should repeat the remark 
already alluded to in page 444. In fact, on referring to the observation book, 
I find that the intervals of the coincidences were only 14 seconds : and I fear 
that a sufficient number of them were not taken, to insure that degree of accu- 
racy which is requisite in such minute inquiries. I should therefore give the 
preference to the preceding set of experiments. 
The next and last class of experiments was necessarily very limited ; as, 
from the construction of my vacuum apparatus, I could not conveniently ex- 
tend them so far as I could wish. They were instituted for the purpose of 
determining the difference between the results of the brass cylinders, and the 
thin brass discs swung edgeways , and the results when swung in the manner 
already described ; namely, with their flat sides opposed to the line of motion. 
The two cylinders, used in the preceding set, and the two discs respectively 
2'0/ and 3 f 01 inches in diameter, were chosen for this purpose. The two cylin- 
ders were screwed, as before, to the end of the long brass rod ; in order to 
compare their results with the preceding set : but the two discs were screwed 
to the brass rod, at 38 inches from the knife edge, in order to compare their 
results with those of No, 75 in the eighteenth set. The several results are as 
follow : 
* See the first note in page 443. 
