387 
iron arising from its rotation. 
of the plate are in the following columns, which are in pairs, 
the one showing the inclination indicated by the southern 
extremity of the needle, the other, that by the northern. 
Above the pairs of columns, is indicated the direction in which 
the upper or polar south edge of the plate revolved, with re- 
ference to the points in the equator, and also the direction in- 
which the equatorial south edge of the plate revolved with 
reference to the polar points in the plane of the axis. Under 
the columns, are the mean inclinations of the needle when 
the plate revolved in opposite directions, and below these, the 
mean deviation due to rotation. 
VIII. Table of the inclinations of the dipping needle when the centre of the plate 
was in longitude 0°, latitude 0°, and its plane parallel to the meridian ; so that 
the axis of rotation of the plate was the same as the axis of vibration of the 
needle : the distance of the centre of the plate from that of the needle being 
9.5 inches. Plate No. I. ' 
Points on the 
Plate coincid- 
ing with the 
Pdar South. 
Polar South edge of the Plate to Equatorial North, 
or 
Equatorial South edge to Polar South. 
Polar South edge of the Plate to Equatorial South, 
or 
Equatorial South edge to Polar North. 
First Set. 
Second Set. 
First Set. 
Second Set. 
S, end. 
N. end. 
S. end. 
N. end. 
S. end. 
N. end. 
S. end. 
N. end. 
O 
6o 
120 
i8o 
240 
300 
0 / 
70 30 
70 10 
70 45 
70 40 
70 55 
71 05 
0 / 
70 45 
70 25 
71 oo- 
70 55 
71 10 
71 20 
0 / 
70 30 
70 3c 
70 25 
70 25 
70 40 
70 45 
0 / 
70 20 
70 20 
70 15 
70 20 
70 30 
70 35 
0 / 
71 40 
71 45 
71 25 
71 00 
71 30 
71 30 
0 / 
71 35 
, 71 40 
71 20 
70 55 
71 20 
72 00 
0 / 
71 25 
71 05 
71 05 
72 00 
71 20 
71 05 
0 , 
71 20 
71 00 
71 00 
70 55 
71 15 
71 00 
Mean dip. 78® 38' 
71° 18' 
Mean deviation due to rotation. 0° 40' 
From these observations it appears that, in this position of 
the plate, the deviatioji of the upper, or south end of the needle, 
3 E 
MDCCCXXV. 
