Microlite, _C. U. Shepard_, xxvii, 361; xxxii, 338; xliii, 116; xlviii, 176. ----, identical with pyrochlore, _J. E. Teschemacher_ and _A. A. Hayes_, xliii, 33. ----, reply to, ibid, by _C. U. Shepard_, xliii, 116; xlviii, 176. ----, analysis of, _A. A. Hayes_, xlvi, 158. Micrometers, artificial spider's web for, xv, 183. Microscope, on improvements in, _E. Thomas_, xix, 57.^f ----, on the achromatic, _E. Thomas_, xx, 265.^f ----, monochromatic lamp of _D. Brewster_ for, vii, 363. ---- and microscopical observations, notice of, xli, 205. Microscopic life, see _Infusoria_, and _Zoology_. Migration of birds, note on, x, 192. ---- ----, of North America, _J. Bachman_, xxx, 81. Mildew, prevention of, iii, 385. Milk, mode of preserving indefinitely, xviii, 152. ----, use of, in dropsy, xxiv, 209. ----, facts from _Barruel_ respecting the milk sold in Paris, xvii, 378. Milk tree of Venezuela, xix, 373. Milking, principle of the balance applied to, _H. Strait_, xxvii, 92.^f Milkweed, Asclepias Syriaca, a substitute for flax, xxvii, 384. ----, on the fibre of, xxviii, 380. _Miller, E._, canals of Pennsylvania, xxv, 84; xxvi, 108. ----, on tracing oval arches, xxii, 303.^f Millet's smoke disperser, xvii, 164. Milo, catacombs of, xvi, 331.^f ----, caves of, containing alum, xvi, 334. Mines, depth of different, xxix, 374. ----, wire ropes for deep, xxxv, 319. ----, general remarks on the positions of, _Taylor_, xxxiv, 9. ---- of Pasco, S. A., xvii, 43.^f ---- of the Hartz, and mode of working, xix, 113. ---- of Idria, xxix, 219. ---- of Michigan, position of, _D. Houghton_, xli, 183. ---- of Russia, see under _Russia_. ---- of Spain, xxviii, 17, 21, 144. ---- of Tokat, xxxvii, 352. ----, see farther, under names of _Countries_, _Metals_ and _Minerals_.