= 
N+ 
P. E. Chase on Mechanical Polarity. 91 
82. If a candle-flame, or the smoke of an extinguished taper, 
be brought near to the revolving ring, it will be repelled from 
the equator, attracted to the poles, and neither attracted nor re- 
pelled at a distance of about 30° from the equator. 
a magnetic needle is substituted for the taper, it tends 
to parallelism with the axis at the equator, and dips toward the 
center as 1t approaches the poles, in accordance with its general 
disposition to range itself in the line of strongest vibration. 
(Exp. 8, Proc. A. P. S.; ix, 359.) 
D. Revoitvine Discs arracnep to THE Rive. 
a. Dises Arial. 
84, Whatever may be the position of the axis, there is a very 
slight axial polarity. 
b. Dises Perpendicular to Axis. 
35. There is no current-polarity. 
c. Discs with 45° Kast Declination, 
oa If the axis is in the meridian, the needle declines to the 
37. If the axis is in the equator, when the top of the ring 
Moves south the needle declines to the east, but when the ring 
moves north the declination is westerly. 
38. If the axis is inclined to the meridian, and the dise passes 
Over the needle in the magnetic equator, the declination is 
easterly; but if the disc is meridional, I am unable to discover 
any decided current-polarity. 
d. Discs with 45° West Declination. 
39. Placing the axis in the meridian, the needle declines to 
the west. : 
40. When the axis is equatorial, the declination is westerly. 
41. When the axis is inclined to the meridian, and the disc is 
€quatorial, the needle declines to the west; but if the disc is 
meridional, it produces no marked ity. 
42. All of the experiments with revolving dises, as well as 
a those with tixed discs, appear to be affected by chan; 
im the earth-currents, especially when the motion of the ring 
Is hortherly, ee Heuer 
are a ag results are in precise accordance with the theo- 
‘etical deductions contained in my papers on the ‘‘ Numerical 
ations of Gravity and aca” on the “Influence of 
Gravity on Magnetic Declination,” and on “Gravity and Mag- 
netic | nolination” (Amer. Phil. Soc., ‘Dec. 16, 1864, April at e 
ay 19, 1865, and this Journal [2], xxxix, 812; xl, 83 
and M. 
1 
as well as with Dove's discovery that analogous ate = 
