Radiant heat, transmission of, _M. Melloni_, xxvii, 228. ---- ----, _B. Powell_, xl, 313. Radiation of heat, _A. D. Bache_, xxx, 16; xxxiv, 39. ---- ----, apparatus for illustrating, xxviii, 320.^f Radius of the earth, xxxi, 234. _Rae, J._, balloon raised by solar heat, xxxiii, 196. _Rafinesque, C. S._, progress of vegetation near Philadelphia, i, 77. ----, on atmospherical dust, i, 397. ----, on the genus Flœrkea, i, 373. ----, new species of grass, Diplocea barbata, i, 252. ----, Cylactis, Nemopanthus and Polanisia, three genera of New York plants, i, 377. ----, description of the Xanthium maculatum, i, 151. ----, new genus (Exoglossum) of freshwater fish, i, 155. ----, Mustela vulpina, new species, i, 82. ----, Scytalus cupreus, or copper headed snake, i, 84. ----, sponges on Long Island shores, i, 149. ----, notice of the works of, xxix, 393, 394. ----, ---- of zoological writings of, _S. S. Haldeman_, xlii, 280. ----, ---- of the Botanical writings of, xl, 221. Railroads in Austria, xx, 174. ---- in the United States, extent of, _J. Henry_, xxxiii, 296. ----, Hudson and Mohawk, account of, _S. D. Bloodgood_, xxi, 141. ----, graduation of Mohawk and Hudson, xxi, 385.^f ----, Baltimore, method of clearing the snow from, xx, 166.^f ---- curves, _T. Gorton_, xxvii, 131.^f ----, elevation of, required for rails, over roads of a certain curvature, _J. Thomson_, xxii, 346.^f ----, inclined planes in the construction of, _J. Thomson_, xxiii, 107. ----, turnouts in, with flexible moveable rails, _T. Gorton_, xxviii, 248. ---- cars, rapidity consistent with safety, xxxv, 197. ----, improved method of constructing, xxxv, 318. ----, cast iron sleepers for, xxxv, 318. ----, resistance of air to trains of, xxxviii, 136. ----, atmospheric, xlix, 228. ---- tunnel, in Pennsylvania, xxix, 73. Railways, vibration of, _Denham_, xxx, 382. Railway iron, remarks on, _D. Mushet_, xxxiv, 15.