Baron Richthofen remarked, that gold occurs associated with mispickel in Silesia. Mr. R. L. Harris made some remarks on the comparative friction of car-wheels, on an iron track, when rolling and sliding, as shown by experiments made on the street-railroad in Washington street. Here the greatest grade is five hundred and twenty-eight feet per mile, or one in ten, and it is found that, on a wet day, if the wheels are stopped by the brakes, they will slide on the track; while, if the brakes are not put down so hard but that the wheels can revolve, the car is entirely under control. This is not the popular opinion, and the authorities generally state, that the sliding friction is the greatest; but experience shows, that the friction is really greatest when the sliding and rolling motions are combined. REGULAR MEETING, FEBRUARY 16TH, 1863. President in the Chair. Fourteen members present. Donations to the Cabinet were received as follows: From J. E. Clayton, Esq., a set of ores from the Russ District, California. Donations to the Library: Proceedings of the Zoological Society of London for the year 1857: from Dr. Cooper. Astronomical and Meteorological Observations, made at the U. S. Naval Observatory during the year 1861: from the U. S. Naval Observatory. Dr. Kellogg read the following paper: Description of two New Species of Plants from Nevada Territory. BY A. KELLOGG, M.D. APLOPAPPUS Cass. _A. Nevadensis_ Kellogg. [FIG. 1.] [Illustration: FIG. 1.] Suffrutescent, caudex branching, branches three to four inches in height, somewhat ascending; rigid, striate, scabrous throughout. Heads solitary and terminal, homochromous and many-flowered. Leaves alternate, crowded near the base, oblanceolate, very acute, quite entire, three-nerved; the reticulate veins and nerves prominent, sub-petiolate (half to one inch in length, by about one-fourth in breadth); the lowermost leaves more distinctly petiolate, spatulate, obtuse, or sub-acute; upper cauline leaves few or solitary, lanceolate, very acute or acuminate, three-nerved. Involucre campanulate, the greenish somewhat foliaceous scales rigid, many-nerved, (chiefly three to five) margins scarious, cleft-ciliate, or somewhat fimbriate, oblanceolate, acute, in three series, often one or two bractoid scales at the base. Receptacle flat, alveolate; alveoli toothed, naked. Rays (about eight) orange-yellow, oblong-oval, two or three-toothed, pistillate, fertile, tube slender, about as long as the achenia, or one-third to half the length of the ligule. Disk corolla cylindrical, slightly expanding, five-toothed, erect, glabrous. The achenia (about twenty, including the ray) angular, oblong, somewhat compressed; base cuneate, satiny appressed pubescent (with white hairs); pappus of unequal capillary scabrous bristles, rigid and fragile, or deciduous.