316 P. E. Chase on the relations of Gravity and Magnetism. 
striking to encourage a hope that our knowledge of the moon’s 
perturbations may be improved by a thorough comparative study 
of the lunar astronomical, atmospheric, and magnetic tables. 
Lunar-daily disturbances of Magnetic Force at St. Helena, in millionths 
of the total force. 
| 3. pO; 1] p84 4-) 5.1.6.,7181-9.1 lg Heo 
Before Lunar M,|-+5|—1/+4 2 —6 2 14 |+15 |+16 
After “ “|4+5/-1/—5 |-6'—7/—6 [+1 /+1/—2/418 [+25 |422 [+16 
Mean, 45|—1|—0-5|—4/—6/—5-5 —25}-1/-9/+ 8-5|-+195/4185/+1 
Rotation-Tide. | 0| O+46 424145 F35|/F2| OF S/F FSF 35 
The above table shows, that 
. The moon’s attractive force (M+ R?=-016+60?=:000004) 
multiplied by the coéfficient of its differential attraction (2'50) 
gives ‘0000113, which is nearly the same as the mean meridional 
magnetic disturbance [(000005+-000016)+2=-0000105]. 
2. The increase of magnetism at 125 is nearly equivalent to 
the attractive force, multiplied by the square of the distance 
from the center of gravity of the system, and divided by the 
square of the earth’s radius (000004. 77072 +3963? = 0000168). 
3. There is a tendency to equality of disturbances on each 
side of the meridian at 14 and 84, as in the solar magnetic tide. 
4. The greatest disturbance occurs at the hours of 104 and 11 
P. M., both in the solar and in the lunar tide. 
5. There are some indications of an increase of gravity, and 
decrease of magnetic force, when the tidal flow is toward the 
center of gravity of the terrestrial system, and vice versa. 
e rotation-tide has the customary quarter-daily phases 
of alternate increase and diminution. : 
X. The phenomena of magnetic storms indicate the existence 
of controlling laws, analogous to those which regulate the nor 
mal fluctuations. See Proceedings Amer. Phil. Soc., Oct. 21, 
1864. 
The foregoing comparisons have been based on Gen. Sabine 
discussions of the St. Helena records. It would be desirable, ' 
port to my views. 
