is a precipitous mountain, nearly a thousand feet in height; and it was on its top, and near the western edge, that the native iron was found, not three years ago as stated in this Journal, but as Major Burrall informed us, sixteen or seventeen years since. At the base of the mountain is limestone, succeeded by an aggregate of quartz and mica, which appears to be one of the varieties of Dr. Macculloch's quartz-rock. The top of the mountain, however, is well characterized mica-slate, containing small imperfect crystals of magnetic iron-ore, sparingly disseminated. On the top of the mountain we came to a pond, perhaps sixty or eighty rods across; and on the southwest margin of this pond is the spot where, as well as Major Burrall can recollect, he obtained the specimens in question. At this spot he found his compass liable to so great a variation that it was useless; and on examining the rocks for the cause, he found the specimens that have excited so much interest. Mr. Burrall, junior, took his father's compass with him, on our present excursion, and attempted to run over the same line which his father pointed out to him, as the one upon which he experienced so much difficulty. This line runs nearly east and west, just upon the southern margin of the pond; and we found that where it approaches the nearest to the pond, there was a variation of 30°, as shown by back objects. On setting the compass only two or three rods backwards or forwards on the line, however, the variation almost entirely vanished. This showed us that the magnetic mass, that produced the variation, could not be far removed from the line, either north or south; for had it been at a considerable distance, the removal of the compass a few rods either east or west, could not materially have af fected the variation; since the radius of a large circle for a considerable number of degrees, differs so little from the secant. We removed the compass one or two rods to the north, and ran a line parallel to that above named, so as even to enter a little distance into the pond, where the water is highest. Here the variation was even greater than upon the first line; so that the attracting mass must lie north of that first line. Probably it lies just in the edge of the pond; and I have no hesitation in saying, that a circle, described with a radius of two rods, upon the point where the greatest variation was noticed, would embrace the ferruginous mass that here disturbs the needle; nor is there much reason to doubt but that mass is native iron. And whoever has observed how large a mass of iron it requires to turn aside the needle of a compass, at the distance of one or two rods, will presume that the mass here deposited must be a large one. The spot I have been describing is co-, vered with trees and thick underbrush, and the moss and rubbish almost entirely hide the rocks underneath. The bottom of the pond is sphagnous; and perhaps it might be necessary partially to drain it, which is not difficult. Whoever will be at the trouble and expense of removing the brush, moss and soil, at this spot, under the direction of Mr. Burrall, or Dr. Reed, will, I have little doubt, be abundantly rewarded by the discovery of a mass of native iron." "On secing this pond, and considering this locality of native iron on on its margin, the inquiry forces itself on the mind,-may it not be the crater of an extinct volcano? But I could perceive not the least indication of any igneous action." "Major Burrall presented me with a small specimen of the native iron, whose characters correspond exactly to those given in the 12th volume of this Journal; but it furnishes no additional information."-Silliman's Journal, vol. xiv. p. 223. In the review of Prof. Olmsted's official "Report on the Geology of North Carolina," given in the same Number, p. 235, occurs the subjoined notice of specimens of native iron from that state. "One of the specimens of iron-ore sent to Prof. Olmsted, from the slate-formation, or gold-region, proved to be native iron. Another was afterwards discovered that weighed twenty-seven pounds, and a part of it was wrought by the blacksmiths."-p. 31 and 108. An account of the slightly arseniuretted native iron of Bedford county, Connecticut, (also extracted from Silliman's Journal,) will be found in the present volume of the Phil. Mag. and Annals, .p. 73. FOSSIL REPTILES. M. Jæger, in his work Uber die Fossile Reptilien, welche in Würtemberg aufgefunden worden sind, Stuttgart, 1828, gives the following list of fossil reptiles found in the Wirtemberg rocks: Mr. Cooke, surgeon (Trinity Square, Tower Hill), having been very successful in his endeavours to preserve anatomical preparations in salt and water, was requested to try to preserve in the same way a specimen of Clavaria muscoides (Sowerby's English Fungi), supposing that it might answer for funguses of some kinds. Mr. Cooke in a written account says: "I put it into brine a little below saturation, suspending it by a delicate thread of silk, and closing the bottle by means of glass. Since that time it has remained in the solution, and with the exception of having become a little deeper in colour it is unchanged. As spirits are not only ex pensive, pensive, but usually deprive plants of all colour, the discovery of a cheap and effectual solution for the preservation of plants is a desideratum." The specimen was gathered at the latter end of October 1826, and was presented to the Linnæan Society in May last, with an account of the process. As many species of funguses may be expected to appear at the latter end of this month and in the next, persons who are desirous of trying the before-mentioned method of preserving such vegetables, will no doubt have an opportunity of so doing. Sept. 17, 1828. B. M. FORSter. DIFFERENCE OF LONGITUDE BETWEEN PARIS AND GREENWICH. Captain Kater in his account of trigonometrical operations for determining this difference, (published in Part I. of the Phil. Trans. for the present year,) observes, p. 193, that the quantity 2° 30' 17"-73, obtained by those operations, "converted into time is 9m 21.18, differing only 0.28 in defect from the admirable results obtained by the operations with fire-signals, reported in the Phil. Trans. for 1826, by Mr. Herschel." It may possibly save trouble to some future inquirers, to state, that Captain Kater here refers to the results of Mr. Herschel's operations, as corrected by Mr. Henderson in the Phil. Trans. for 1827, p. 295 (see also Phil. Mag. and Annals, N. S., vol. ii. p. 142), which give 9m 21.46, or 9m 215-5, to the nearest tenth of a second, instead of 9m 215-568, and 9m 21-6, as given in Mr. Herschel's paper. Mr. Ivory also, in his paper On the measurement of degrees perpendicular to the meridian, in the last Number of the Phil. Mag. and Annals, refers to the same determination as corrected by Mr. Henderson; though he, like Captain Kater, refers only to the original paper in the Phil. Trans. for 1826, without mentioning Mr. Henderson's recomputation in the same work for 1827. FIGURE OF THE CELLS OF THE HONEYCOMB. To the Editors of the Philosophical Magazine and Annals. En faisant des récherches sur les alvéoles des abeilles *, j'ai recueilli les détails suivans, qui peuvent servir à l'histoire du problème proposé par Reaumur. 1°. Le professeur Cramer, de Genève, envoya à Koenig, en 1739, une solution qui ne différait pas de la sienne, étant appuyée comme elle sur le calcul de l'infini. Toutes les deux sont perdues. 2°. Le Père Boscowich, sans avoir connaissance de la méthode de Maclaurin, résolut comme lui le problème par la considération des maxima et minima. On trouve cette solution dans ses remarques sur le poëme de Stay. 3°. Enfin, Lhuilier, de Genève, a résolu aussi le problème, par un procédé plus simple encore que celui de Maclaurin, puisqu'il arrive au même résultat, sans employer la considération des maxima et minima: ce n'est plus qu'une question de géométrie commune. * See p. 20 and p. 233 of the present volume of the Phil. Mag. and Annals.-EDIT. New Series. Vol. 4. No. 22. Oct. 1828. 2 S Vos Vos lecteurs, pour s'en assurer, peuvent recourir aux Mémoires de l'Académie de Berlin, année 1781. FAYOLLE. ON VARIGNON'S METHOD OF SOLVING EQUATIONS OF THE SECOND DEGREE. BY M. FAYOLLE. To the Editors of the Philosophical Magazine and Annals. Messieurs, La méthode que vous avez insérée dans votre dernier numéro, pour la résolution des équations du second degré, m'en a rappellé une de Varignon qui est encore plus simple, et qui s'applique aux équations du troisième degré. Elle est si facile (disait Fontenelle), qu'on est tout surpris que Varignon l'ait trouvée le premier. La voici en peu de mots: Laquelle comparée terme à terme avec la proposée, donnera Si l'on avait z-pz+q=0, Il faudrait prendre z=x+ Y: Cette méthode s'applique avec la même facilité à l'équation du troisième degré z3 + p z + q = 0, Laquelle est dégagée du second terme. Ce 16 Aug. 1828. MINERALOGICAL LITERATURE. FAYOLLE. 1. Dr. Naumann, professor in the Mining Academy of Freiberg, has published Lehrbuch der Mineralogie (Treatise on Mineralogy), Berlin, 1828, by A. Rucker, in 8vo. This treatise, by a scholar of the celebrated Professor Mohs of Vienna, is one of the best on that science. The crystallographic method of Professor Naumann is eclectic in reference to those of Mohs and Weiss, and is very good; the system is established according to the physical and chemical characters of minerals. He describes a multitude of varieties of crystals with the assistance of 556 figures. In general the work is very classical, and deserves to be recommended to mineralogists. 12. Dr. Charles Hartmann, Mining-officer in the service of his Highness the Duke of Brunswick, has published Worterbuch der Mineralogie und Geognosie, (Dictionary of Mineralogy and Geology). Leipsic, by Brockhaus, 8vo. This work gives a description of all known minerals and rocks in alphabetical order, and contains an introduction introduction to mineralogy and geology, with the history and literature of the sciences in systematical arrangement. In reference to the crystallography, Dr. Hartmann pursues the methods of Professor Mohs and of Professor Weiss. This work merits the particular notice of all mineralogists, and also travellers, because the size of the book is not great, and the type very small. A German, an English, a French, and an Italian index facilitate the use of the book, and 312 figures illustrate the forms of the crystals. 3. Dr. Hartmann has also published Vorlesungen über Mineralogie, &c.,-(Lectures on Mineralogy, particularly for Schools,) &c. Ilmenau, by Voigt, 8vo. This elementary treatise is strongly recommended to young men who study the natural history of minerals, and to lecturers in schools. As in the elementary introduction of Mr. Phillips, the crystalline forms of minerals are illustrated with wood-cuts printed along with the text. SCIENTIFIC BOOKS. Just published. No. I. of Zoological Researches and Illustrations; or Natural History of Nondescript or imperfectly known animals, in a series of Memoirs: illustrated by numerous figures. By John V. Thompson, Esq., F.L.S., Surgeon to the Forces; author of A memoir on Pentacrinus Europeus. This first Number contains the following memoirs: 1. On the metamorphoses of the Crustacea, and on the animals forming the genus Zoea, exposing their singular structure, and demonstrating that they are not, as has been supposed, a peculiar genus, but the larvæ of Crustacea with two Plates. 2. On the genus Mysis, or Opossum Shrimp; also with two Plates. The author of this novel contribution to the stores of zoological science, has we understand devoted much time and exertion to the collection and preparation of materials for the work. They are wholly original, and the results of observation on animals of every class, but more especially on the marine Invertebrata, in both hemispheres of the world. No. II. will be published in January; and the succeeding Numbers at intervals of three or four months. Elements of Algebra. By Robert Wallace, A.M., late Andersonian Professor of Mathematics, Glasgow. A Circular, explanatory of Skene's patent as applicable to steamnavigation, and undershot water-mills. No. II., for the year 1829, of the "Enigmatical Entertainer and Mathematical Associate." In the Press. An American reprint of Mr. Bakewell's new and enlarged edition of his "Introduction to Geology" is announced, under the superintendence of Professor Silliman. A second edition, considerably enlarged, of Mr. De la Beche's Tobular and Proportional View of the Tertiary and Secondary Rocks. 952 LIST |