F 
. 
i 
i 
4 
P.E. Chase on the relations of Gravity and Magnetism. 313 
strated, the influence of the sun upon terrestrial magnetism ; 
Secchi ascertained that “the diurnal excursion of the needle is 
_thesum of two distinct excursions, of which the first depends 
 tolely on a horary angle, and the second depends, besides, on 
the sun’s declination,”* and that “all the phenomena hitherto 
known of the diurnal magnetic variations may be explained by 
‘Supposing that the sun acts upon the earth as a very powerful 
‘Magnet at a great distance.” 
This hypothesis has been objected to, on the ground that it is 
- dificult to understand how any conceivable intensity of solar 
agnetism, by its simple induction, could produce so great a 
disturbance as is daily observed. Therefore it will probabl 
7 follow the fate of the earlier ones, which attributed terrestrial 
_ttagnetism to one or more powerful magnets lying nearly in 
the less interesting 
Ean fom VM 
the line of the earth’s axis, while Barlow’s idea that the mag- 
-Ietism is superficial, and in some manner induced,” will still re- 
main in the ascendant. Secchi’s conclusions are, however, none 
and from the fact that magnetism is, like 
o>) 
: sala a central force, varying inversely as the square of the 
lance, they lend encouragement to those who are endeavoring 
Wofind new evidences of the-unity of force. 
, -y.OWn experiments and researches have led me to the belief 
that all magnetism is a simple reaction against a force which dis- 
-torbs molecular equilibrium, that the numerical equivalent of 
the Magnetic force is therefore equal and opposite to that of the 
urbing force, (+ M === D), and that all the phenomena of 
restrial magnetism result from tidal and thermal changes in 
“restrial gravitation. 
" Sullivan’ and Reinsch’ have pointed out the effect of musical 
Tibrations upon the magnetic needle, and I have shown the con- 
ug influence of a purely mechanical polarity.” A careful 
‘amination of the polarizing thermal and rotation currents, 
: will show that the spirals, which they have a tendency to pro- 
an? te quasi horizontal cyclones, one set flowing in a nearly 
“i direction along the magnetic meridian, and the other 
" ard the momentarily shifting solar meridian. From an in- 
‘estigation of these currents and a comparison of various obser- 
ons, Ihave deduced the following theses : 
: I. ‘he daily magnetic variations, though subject to great dis- 
ifferences of the gravitation-tidal currents. 
a ak eae 1h. 2h. sh. 
of Theoretical Ratios, =e 284 2? ge 
\ “ % Observed : be 2 . -563 "865 i 
the hs at different hours, show an average approximation to 
? 
(, Phil. Mag. £43, vit ', : © Ted te, 452 § Phil. Trans., 1831. 
cay, gases 1 RM Moe fo ison 
Froe. A. P: s., ix, 359, o> ™ f Ibid., p. 867 seq. 
