INDEX. 
secondary effect, 164 — its proximate cause, 165 — internal cur- 
rents in, 166 — various phenomena explained by, 166 — remains 
at rest under caustic soda and potash, when perfectly pure, 179 
■ — effect of various metals in alloy with, 179 — contact of various 
metals with, under liquids, singular effects of, 187 — different 
when recently electrified, and when not, 187-188. 
Metal, fusible, its electro-mechanical properties, 186. 
Metals, various, their effects in altering the electro-mechanical re- 
lations of mercury, 179 — bear a relation to their electro-positive 
energies, 184. 
Micrometers , repeating, iii. 9 — used by Messrs. Herschel and 
South, iii. 9.-— value of scale, how determined, iii. 13 — tables of, 
iii. 23. 
Migration of birds, Jenner on the, 11, et seq. — reality of, 12 — 
cause of, the generative instinct, 20 — another cause of, the de- 
sire to revisit their homes after procreation abroad, 27. 
Mixtures, gaseous — explosive ; vide explosive and gaseous. 
Moll, his experiments on the velocity of sound in Holland, 424. 
Mollusca, naked, only occur in tertiary formations, 415. 
Moor -hen, its powers of flight, 16. 
Moth , brain of, 10, Plate II. 
Motions in fluids produced by electricity, 162. 
Mucus, an ingredient in bile of walrus ; — secreted on the coats of 
the gall-bladder, 236. 
Mudge, his observations in 1802, used to try the southern motion 
of stars, 52. 
Mural circle at Greenwich. Assimilated by Mr. Pond to a theo- 
dolite, 472 — its microscopes supposed unsteady, and why, 494, 
497 —a table of discordances between its microscopes, 490. 
Muriatic acid in the stomach of animals, 46 — in the human ditto, 
49 . 
— gas, its effect on explosive mixtures of hydrogen 
and oxygen submitted to the platina sponge, 274. 
N 
Nail of iron tied by a copper wire to 40 square inches of copper, 
preserved it from the action of sea- water, 157. 
Negative electricity not to be supposed favourable to life, 158. 
Nerves, optic. Wollaston on the semi -decussation of, 222 —their 
structure explained, 226. 
Nightingale, migration of, 29. 
