450 
MR. BAILY ON THE CORRECTION OF 
pendulum No. 12, as described in the preceding part of this paper. The fol¬ 
lowing are the results. 
Seventeenth set.— Results with the 2-inch cylinders placed at the centre of 
oscillation of the long rods. 
Thickness 
of the 
cylinders. 
Brass rod. 
Steel rod. 
No. 
n 
Weight of 
adhesive 
air. 
Weight due 
to cylinder 
alone. 
No. 
n 
Weight of 
adhesive 
air. 
Weight due 
to cylinder 
alone. 
inches. 
0-00* 
0-18 
0-50 
1-00 
2-06 
43 
67 
68 
69 
70 
4- 083 
5- 547 
3-941 
2-892 
2-141 
1- 484 
2- 852 
2-942 
2- 972 
3- 111 
1-284 
1-523 
1-681 
1-902 
44 
71 
72 
73 
74 
7-530 
7-694 
4-136 
2-745 
1-988 
0-479 
1-806 
1-900 
2-046 
2-309 
1-350 
1-490 
1-661 
1-946 
Here we find a regular increase in the value of n, as the thickness of the 
cylinder diminishes; till it approaches nearly equal to the thickness of the 
rod itself, when the effect of the cylinder on the value of n is eliminated, 
and the result is the same as if no cylinder were attached to the rod. Pass¬ 
ing this point, and the thickness of the cylinder becoming equal to, or less than, 
the diameter of the rod, the effect of the cylinder becomes positive; and the 
value of n is now greater than when the rods are swung without any thing 
attached thereto. Setting aside however the value of n, and confining our 
attention to the quantity of air adhering to, or dragged by, these pendulums, 
we find that it varies with the thickness of the cylinders. And, pursuing the 
same steps, as in the case of the spheres (see page 446), we obtain the values 
above given, for the weight of air due to the cylinders alone ; and which are 
more conveniently arranged in the following form: viz. 
* See the first note in page 443. It must be noted here that in the first horizontal line, no cylin¬ 
der is supposed to be attached to the rod: and therefore these values are not directly comparable with 
the rest. 
