118 P. E. Chase on Terrestrial 
poles to the equator, and against the earth’s rotation; the upper 
from the equator to the poles, and in the same direction as the 
earth’s rotation; the two being connected by inna cure 
rents of convection, or threads of ascending and escending 
particles. It will also be evident that at every mye “thet are 
two principal sets of such double spirals, one with an axis per 
pendicular to the earth’s radius vector, producing a maxim mur 
disturbance in the early afternoon, and the other more stableand: 
uniform, with an axis passing through the nearest poles of greak 
est cold. In addition to the mutual perturbations of these two 
principal polarizing currents, the rolling of the luni-tidal alt 
tion-wave produces at every instant a “greater or less derang' 
ment,” and I find that the ratio of the lunar-barometric to 
lunar-magnetic disturbance, (4:884), is nearly identical with ie 
Welsh’s determination of the moment of magnetic inertia (4° 
Phil. Trans., cliii, 297). From a variety “of considerations, 7 
appears that the mechanical polarity or magnetic force thus en 
gendered is a third proportional to two other forces, which may 
be called, respectively, central and tangentia 
The communication which was presented at the meeting of 
Oct. 7, in its exhibition of the first numerical relationship ee 
as even been pointed out Seaeents the barometric and magnet’ 
Spe toi showed that A: B:: B: M, a proportion in qi 
nts a central, Ba eaasculial: and Ma magnetic force. 
I ind a similar Biopordionalty 3 in ca of Mr. Airy’s i 
f Ho 
al 
e Mea 
Pairs force. Ni Sec lir force. 
— -00023=M. nae ot boat. “00057=C- 
Here the proportion T: © :: GC: M gives for Ma 
Theoretical value, 5 ; 000222 
Observed = 900228 
bable etror, PB “000080 
“Table IIT. pega: Sums of Magnetic F Fluctuations (i 
terms of Horizontal Force) for each Year, from su o 1be) 
Theoretical value of ¥, . . —-000287 
red “6 ‘ i e er boas 
Probable error, : E j 00068 
? Besides the e great disturbing be ae 
pace ies, whose effects ma: haps 2 
paride ope gr prediction transient local cnet of hee : 
will exert a ience, Ever 
village that can produce currents or 
of the “ mae be med to affect the ether, and 4 the inconceivable, ot 
: wthereal motions, 2 manifested in the velocit ty of oe waves 
eat, will account for the extreme sensitiveness of the magnet 
ae 
