MAG 
Magnetic needle, improvement in, 
reply to the same, xii, 232. 
, made of thin plates not 
in contact, W. Scoresby, xxxiv,| 
398. 
, oscillations of, differing! 
near different metals, xv, 182. 
, polarity and dip of, a 
remark on, xxix, 353. 
, made to indicate the 
true north, xxvi, 90. 
, on the connexion of the 
theory of the earth with the sec- 
ular variations of, J. H. Lathrop, 
XXXvill, 68. 
needles, best position of three, 
for mutual action, H. Lloyd, 
XXXvill, 96. 
observations, a union of ef- 
fort urged for carrying on, xviii, 
380. 
, great scheme for, by 
the Royal Society of London, 
xxxvil, 198. 
, ibid, by British Asso- 
ciation, xl, 8385; xlii, 151; xlii, 
374, 
, in Russia and oth- 
er countries, in progress, xlii, 
153. 
—— 
, cooperation of the 
Amer. Acad. of Arts and Scien- 
ces ina general system of, xxxix, 
193. 
———— 
, corresponding, by A. 
D. Bache and H. Lloyd, xli, 
260. 
observatory at Dublin, xxxiv, 
3. 
poles, revolution of the two, 
XxXix, 392. 
polarity, notice of, D. H. 
Barnes, xiii, 70. 
, reply to D. H. Barnes, 
xiv, 121. 
of rocks, xx, 198. 
—— power of a galvanic battery, 
v, 388. 
separating machine for mag- 
etic ores of iron, used at Fran- 
foil 
M AG 
Magnetic variation, daily, different 
in different places, xix, 189. 
, at Perth, Scotland, xl, 
342. 
, at Paris, France, xxxi, 
, remarks on, WV. Bow- 
ditch, xvi, 64. 
, for the United States, 
EF. Loomis, xxxiv, 290f; xxxix, 
41f; xliii, 106. 
, table made from ob- 
servations at Boston, Falmouth 
and Penobscot, xvi, 60. 
, at Providence, R. I., 
M. B. Lockwood, xliv, 314. 
vat Droy yo NBOY), | =xvit; 
198. 
, in some parts of New 
York State, xxxvi, 28. 
, in Connecticut, G. Gil- 
let, xxiii, 205. 
, at Yale College, xxx, 
221. 
, at Westchester, Pa., 
observations by A. D. Bache, 
XXVil, 885. 
Magnetism, animal, v, 192; xii, 
175. 
—— ., Davis’s Manual of, xliii, 381. 
of the earth, especially of the 
arctic regions, E. Sabine, xvii, 
145.f 
, causes of, B. F. Jos- 
lin, xix, 398. 
, views of J. Hamilton, 
xxxvil, 100. 
, views of S. L. Metcalf, 
xxvil, 153. 
, views of Rowall, xli, 
41. 
, effect of, on the pre- 
cipitation of silver, xvi, 262. 
chemical effects of, 
374. 
, supposed influence of, in com- 
binations and crystallizations, by 
O. L. Erdmann, xviii, 395. 
, influence of, xvi, 262. 
Vill, 
conia, xvill, 289. 
, connexion of, withelectricity, 
ili, 886£ 
