cleavage. Octahedral and cubic crystals of magnetic iron sometimes incrust cavities in the stone or brick work of the furnaces. The chytophyllite, (p. 35,) has the formula (Fe, Ĉa) (Si, Al), and consists of Si 54.897 Al 5-078 Fe 20.794 Ča 20.346 101.115 It is foliated columnar, not unlike some kyanite, with the color pearl gray, having a shade of lavender blue. Luster of folia between vitreous and pearly; translucent, when thin. Specific gravity at 15° R. 2.940. H. 55. Breaks with difficulty being tough. B.B. fuses easily with intumescence to a greenish-black glass, not magnetic. New American localities of Minerals; by F. B. HOUGH, A.M., M.D. (Communicated for this Journal.)-Sulphate of Barytes, in a highly crystallized form, associated with an extremely unctuous variety of specular iron ore and serpentine, on the farm of James Morse, in Gouverneur. Specimens from this place are full of angular cavities from the intersection of tabular crystals. Chondrodite occurs abundantly disseminated through white limestone, about three-fourths of a mile west of Somerville, in the town of Rossie. This is the only place where it has been observed in quantity in Northern New York. It is associated as usual with Spinel, in perfect octahedrons with but few modifications. The latter mineral is of a pale rose color, and when in small crystals, is nearly transparent. They occur from an inch to less than a line. in diameter and are frequently grouped together in great numbers. The large crystals are quite rare, but the smaller ones are common. Apatite, in the town of Gouverneur, about two miles north of Somerville. Large crystals occur through the soil and in the subjacent limerock. Most of those hitherto procured have been from the partially decomposed rock. One crystal had a length of one foot and a diameter of two inches. The form of the crystals is very perfect, except the terminal planes which are covered with pits and irregular indentations. The quality is very poor, but doubtless translucent and highly colored specimens might be obtained from the rock. Sphene, in large brown crystals, has been obtained from the town of Macomb, in the vicinity of Pleasant Lake. The quality is very inferior, and crystalline form imperfect. Galena and Zinc Blende, have been observed in considerable quantities in the town of Macomb, about half a mile from the Wilson Lead Mine. It is on the land of James Averil, and is owned by that gentleman and Messrs. Wilson and Smith. These ores occur disseminated through a friable limestone rock, to the width of several feet, and promise a profitable yield of these met als. Carbonate of lead in a white powder is the only associated mineral of interest. Crystallized Specular Iron ore, associated with elegant crys tallizations of quartz, have been discovered on the farm of J. Smith, in Gouverneur, St. Lawrence county. Phlogopite, in large plates and spheroidal concretions, and containing minute crystals of garnet, has been obtained in considerable quantities in a working for iron ore in Gouverneur, near the mill of R. K. Smith. The mica crumbles soon when exposed to the weather. Crystallized specular iron ore is associated with it. Arragonite, in snow-white concretions on surfaces of iron ore, at a new working at the Parish iron mine in Rossie, St. Lawrence county. Tremolite, in great variety and abundance on the farm of F. Arnold, in the town of Diana, Lewis Co., associated with white limestone. Notices of Localities in New England; by Mr. JAS. J. H. GREGORY, of Marblehead, Mass. (Communicated to one of the Editors.) Sullivan, N. H.-Tourmalines! In quartz, of a deep brilliant black, with terminal planes; found about a mile south of the center of the town.-Beryls are said to be found in the same locality. Surry, N. H.-Amethyst; in the great railroad cut imbedded in calcareous spar, but now rare. I was informed that they had been found in other parts of the town. Calc spar, variety called nail-head spar, in slabs lining seams in the granite. Grafton, N. H.-Garnets; from a quarter of an inch to an inch in diameter; well crystallized, but of a dull color and with faces unpolished: very easily obtained from decomposing slate rock. Hartford, Vt.-Calcareous spar, in masses in a ledge cut through by the railroad near the Connecticut river.-Iron pyrites, crystallized in cubes, some of which are two, three, and four inches in diameter and have a good polish, considering their size. Found in a ledge about one-fourth of a mile from the calcareous spar.-Kyanite, in numerous crystals large and distinct, but those I have seen are not generally of a rich color; perhaps this may be accounted for from the fact of their being blasted from the surface. Occurs in numerous veins passing through mica slate, near Hartford center. Bethel, Vt.-Actinolite! In brilliant crystals in talc. Found very abundantly in a dyke passing through a hill-Steatite, containing crystals of bitter spar. Royalston, Mass.-Mica! at a locality situated about four miles beyond the old one in South Royalston. The mica is of a brilliant bronze, crystallized on three sides, and affords specimens much superior to those of the old locality.-Beryls! The beryls approach nearer to aqua-marines and generally are of a smaller size, and clearer, than those of South Royalston. Those of a sky-blue in the white quartz are very beautiful.-Feldspar. In crystals of the same form as those of the old locality, large and scarce. These minerals occur in worn granite on the farm of Mr. Solyman Heyward or Heywood. ART. XLI.-On the Crystallographic Identity of Eumanite and Brookite; by J. D. DANA. A FEW days since, I received for examination from Mr. J. E. Teschemacher of Boston, two minute crystals of the Eumanite of Prof. Shepard. They had been long in his cabinet, and were procured from a specimen of the Chesterfield vein, the same locality that afforded the Eumanite. They have the same dark brown color, with a deep brownish red translucence, "like almandine garnet." The hardness, as Mr. Teschemacher observed, is about 6, or not above 6, scale of Mohs. A comparison of the figures here given will make obvious the identity of the two; figure 1 represents Prof. Shepard's crystal, figure 2, Mr. Teschemacher's. The latter is onlyth of an inch in length, and as no reflection of distinct images could be observed on account of its minuteness, I was compelled to adopt the less accurate mode of measurement by a reflection of the sun's rays. The result has proved that Eumanite and Brookite are very closely similar, not only in physical characters, but also in crystallization. The two crystals strikingly differ though so nearly alike in form. The lateral planes which are the largest in figure 1, are quite small in SECOND SERIES, Vol. XII, No. 36.-Nov., 1851. 51 figure 2, and, the large lateral planes of figure 2 are wanting in figure 1. The angles obtained are as follows, together with those given by Shepard and the corresponding angles of Brookite. The first two of the angles of Brookite mentioned are angles of a vertical and horizontal prism, and consequently they deter mine the dimensions of the crystal and prove the identity as perfectly as if all the other angles were added, the others being deducible from these by calculation. In figure 2, the edges between e, e', e" are parallel; those between a' and the o either side of the plane a'; and those between o, e', e', o are parallel. Figure 2 has the faces, (adopting Levy's fundamental form and axes of Brookite, a=0·5558, b (ě to ě) =0·5957, c = c = 1), Р, P, 2P, P2, P3, αP, 2P, P, αP¤ a' Calculating from these axes gives, e': e'=149°, e': e'=139° 53', e": e"=159° 20′, e': e" 120° 41', o: o (over e') = 100° 26. New Haven, Sept. 23. = ART. XLII. Observations on the Pendulum Experiment; by Rev. C. S. LYMAN. THE fact that the plane of vibration of a free pendulum has a movement in azimuth around the vertical, had been observed by many experimenters, before it was brought so prominently into notice by M. Foucault in connection with the rotation of the earth. This movement is distinctly described, and illustrated by a figure, in some manuscript observations on the motion of a pendulum by the Florentine Academicians, but without any intimation of its cause. That such a motion was to be expected, was also suggested by the Marquis de Poli, (Phil. Trans., 1742,) and by Poisson in 1837, but without giving the subject any further attention, or attempting to test it by experiment. The observed independence of the plane of oscillation of a vibrating steel rod inserted in the revolving arbor of a lathe, appears first to have suggested to M. Foucault the idea that the plane of vibration of a free pendulum would, in like manner, be independent of the rotation of the earth. The experiment was first tried by him with a pendulum six and a half feet in length suspended from the vaulted roof of a cellar, and with entire success. It was subsequently repeated, in connection with M. Arago, at the Paris Observatory, with a pendulum thirty-six feet long. This was in February, 1851. Since that time the experiment has excited general interest, and numerous repetitions of it have been made both in Europe and America. We propose in the present article to give a general summary of information on this subject, derived partly from published accounts, and partly from our own experiments. 1. The method of suspension.-Foucault used a fine steel wire inserted at the top into a hole just large enough to receive it, made in a steel plate which was fastened to the ceiling. The same method of suspension was employed by Mr. Bunt at Bristol, England, by Profs. Carswell and Norton at Providence, R. I., in the experiments at the Capitol in Washington, and in those at New Haven. Indeed this appears to have been the mode generally adopted by those who have repeated the experiments. At the U. S. Armory in Springfield the suspension at top was by means of a pointed steel pivot resting on a hard surface, and the same method has been elsewhere tried, both in this country and in Europe, with a view, probably, in most cases, to avoid friction, but in others, perhaps, to obviate the supposed prejudicial effect of the rotation of the point of support-a matter which, as we shall see, is of no consequence whatever. Others have devised more complicated modes of suspension, such as gimbals with knife edge pivots, the principle being that on which chronometers, marine compasses and barometers are suspended. But besides the danger of errors arising from imperfect workmanship in these complicated devices, it is not certain that they present any advantages over the first named method, viz., the insertion of the upper end of the wire by soldering, or otherwise, in a firm metallic support. If the wire is equally flexible in all directions, this method is as good as can be desired, and whether the wire is thus flexible or not, may be ascertained experimentally in the manner suggested by Prof. Bache at Washington; namely, by placing the portion of the wire at which the flexure |