166 P. E. Chase on Magnetic Inclination. 
ART. tLe and Magnetic Inclination; by PLINY 
hig es S 
RLE CHASE, M.A., 
A SOMEWHAT critical survey of the anomalies presented by 
the magnetic inclination, to which I referred in a former article 
(Proc. Am. Phil. Soc , April 21, 1865), has given me renewed 
reasons for regretting ‘the want of a complete record of the in- 
vestigations on which Prof. Secchi based his conclusions, that all 
‘the phenomena hitherto known of the diurnal magnetic varia- 
tions = be explained by a Lao “ the sun acts upon the 
very powerful magnet at a great distance.” As 
know of mi magnetic law which will pcan for those anomalies, 
I propose briefly to describe them, and to point out some rela- 
_ tions between _ gravitation currents and the dip of the needle, 
as a sequel to my papers on the influence of gravity upon the 
total magnetic ons and the magnetic declination. 
Gen. Sabine’s discussions have shown some important points 
of difference between the magnetic disturbances at inter-tropical 
and extra-tropical stations, the Cape of Good Hope being mag: 
netically, though not geographically, inter-tropical. In the third 
volume of the Toronto Observations, and in Prof. Bache’s discus 
sions of the ahecrxations at Girard ollege, nraieetioes of - 
aily and semi-annual inclination-curves are given;* and Plat 
V, of the second valine of the Hobarton Observations, cael 
a graphical re resentation of the diurnal variations of ‘the incli- 
nation at the ° different observation hours in the four seasons. 
we also project, from Gen. Sabine’s tables of the mean results, 
the daily and semi-annual curves at St. Helena and Cape Colony, 
and compare the curves at the five stations, it will be found oe 
1. The greatest daily disturbance of inclination occurs a 
noon. 
Fro’ oceedings 0 
g Phil Maw: Mag.) ix, 452, o Pecatiog (xr. Rea, iit 403), states that th the pate 
ted Pro m his numerous experiments, which demonstrate ™~ 
se abi prance magnetism upon the same aerial meee ina cesta coh er 
ac hegin ican og induced to consider oe all the other 
enormous maguets, by W ereviirs e es tablished that peer 
as one > elect of the cre aera of the great re ee masses placed at an enor- 
mous distance,—an idea which reappeared in in Prussia, and in 1847 in 
While admitting the inti intimate relationship of magnetism and gravity, I must dis-_ 
sent from the: lasrnes. Fre Professor's inference. For the evidence mea ears “ irre 
's magnetism is directly depend es tion 9: 
thermally disturbed aerial . that it is only slightly ork eth y the per- 
turbations of solar lunar ~epe so that — as & 
causal one, han ion, should 
we 
magretism, sh be considered as 
Sremo at oe Theory of Terrestial Magnetism,” § 30,40; Taylor’s ‘Scientific 
By the kindness of Prof. Henry, T ha been permitted to : 
| is of the Fi Soe: ve perm refer to the ont 
