tral Argentine railway, which has probably been already opened to travel through its entire length of about 250 miles, although information to that effect has not yet reached this country. The two largest instruments will be a Repsold meridian-circle of 54 inches focal length and 44 inches aperture, and an equatorial by Alvan Clark & Sons, provided with the 11 inch object-glass, by Fitz, lately in the posession of W. Rutherfurd who has supplied its place by one of 13 inches. A photometer by Ausfeld of Gotha, according to Zöllner's latest form, has been constructed under the supervision of Prof. Zöllner himself; a spectroscope will be furnished by Merz of Munich, and a clock by Tiede of Berlin. The Scientific institutions of the U. S. have afforded the expedition every possible assistance. The Coast Survey lends a circuitbreaking clock, a chronograph, and a portable transit; the Smithsonian Institution lends a zenith telescope; the American Academy of Arts and Sciences of Boston [probably] a photometer and spectroscope; the Washington Observatory and the Nautical Almanac have greatly aided the undertaking by gifts of books and by a manuscript copy of Gilliss's catalogue of Standard Stars; and from the astronomers of England, Germany and Russia important assistance has been freely and effectively contributed, in the order and supervision of instruments and apparatus, and by the gift of books, as well as by important and valuable suggestions. Four assistants will accompany me, Messrs. Miles Rock, John M. Thome, Clarence L. Hathaway and William M. Davis, Jr. We hope to reach Buenos Ayres not later than the middle of August. The building is now under construction in Boston. The means available proved inadequate for its construction according to the original plan, which was in the form of a cross, with four square rooms about its center, and turrets at its four extremities. One half of it will be first erected; and it is hoped that the remaining portion will speedily be added. 2. Recent Auroral displays in the United States.-We are now near the period of a maximum of the solar spots, and if auroral displays observe a similar periodicity, we must also be near an auroral maximum. The reports made by the observers of the Smithsonian Institution as published with the monthly Reports of the Department of Agriculture have been examined to ascertain the number of auroras recorded upon successive years. Only an occasional observation of the aurora appears in these Reports until the year 1869. It is presumed that the Department of Agriculture did not regard the auroral observations of the preceding years as possessing sufficient general interest to authorize their publication. The following are the dates upon which auroras were reported by at least one of the observers of the Smithsonian Institution for the year 1869, and for three months of the year 1870. 1869, Jan. 3, 5, 6, 7, 10, 13, 17, 18, 19, 20, 21, 22, 30, Feb. 2, 3, 4, 5, 6, 8, 9, 10, 11, 15, 17, 18, 19, March 1, 2, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 30, 31, Total 13 days 13 แ 23 1869, May 3, 4, 5, 6. 7, 8 9, 10 12, 13, 24, 27, 28, 29, June 4, 5, 6, 7, 8, 12. 15, 16, 19. 20, 23, 25, 26, 27. 28, 29. 30, 28, 29, Aug. 1, 3, 5, 6, 7, 10. 14, 15, 16, 22, 24 27, 28, 29, 30, Oct. 1, 2, 4, 5, 6, 8, 9. 12. 21. 22, 24, 25, 26, 27, 28, 30, 31, Dec. 4, 5, 6, 7, 13, 14, 15, 18, 22, 25, 26, 29, 30, Total for the year 1869, 1870, Jan. 1, 2, 3, 4, 5, 6, 7, 8, 9, 16, 18, 24. 25, 26 27, 28, 29, 30, 31, Total 19 days. Feb. 1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 20, 21, 23, 24, 25, 26, 27, 28, March 1, 2, 3. 4 6, 8, 9, 10, 11, 13, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, Total for three months of 1870, 18 23 60 66 These observations indicate a very remarkable number of auroras, but it should be remembered that they are derived from the reports of 350 observers spread over a territory embracing 56 degrees of longitude and 20 degrees of latitude. In order that we may be able to make a comparison with former years, it is desirable to have a similar summary of the reports of all the Smithsonian observers; and it is to be hoped that the Secretary of that Institution will furnish us with such a summary for each year since the Smithsonian system of meteorological observations was commenced. The following summary of the auroral observations made for five years at Depauville, N. Y. (lat. 44° 7' N. long. 76° 3' W.) has been furnished by Mr. Henry Haas. Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. Year. The number of auroras reported for the different years is remarkably uniform, and similar results have been found at other stations where the annual number of auroras rises as high as fifty or upwards; but in lower latitudes where auroral displays are less frequent, the indications of periodicity are unmistakable. V. MISCELLANEOUS SCIENTIFIC INTELLIGENCE. 1. Variations in the Eccentricity of the Earth's Orbit.-In vol. xlvi of this Journal (1868), Prof. J. N. Stockwell has a paper, with a chart, illustrating the variations in the eccentricity of the Earth's orbit for the past one million of years, starting from a point 175,000 years back of the present time; and in an earlier memoir "On the Secular Equation of the Moon's mean motion" published at Cambridge in 1867, he has given a similar chart for the million of years following. His calculations were made for intervals of 10,000 years, and hence they are much more exact than the earlier chart of Croll, whose intervals were, for the major part of it, 50,000 years. The main point put forward by Prof. Stockwell in his Cambridge memoir has not been accepted by astronomers, but this does not affect his calculations of the eccentricity. According to his results for past time, a low maximum occurred about 100,000 years back; a higher, 200,000 years; a lower, 300,000; a rather low minimum 410,000; a low maximum, 475,000; a very low minimum, 520,000; a maximum, 570,000; two maxima, the second 750,000; a very low minimum 800,000; an extreme maximum, 850,000; another very low minimum, 900,000; a high maximum, 950,000; etc.-In future time, there will be a very low minimum, 24,000 years on; a low maximum, 150,000 years; another low maximum, 250,000; a very low minimum, 300,000; a low maximum, 400,000; a very high maximum, 515,000; a minimum, 560,000; an extreme maximum, 610,000 years; and so on. Some of the minor undulations, and most of the minima, are not here noted. 2. Note on an Electrification of an Island; by F. JENKIN.A curious discovery has been made by Mr. Gott, the superintendent of the French company's telegraph station at the little island of St. Pierre Miquelon. There are two telegraph stations on the island. One, worked in connection with the Anglo-American company's lines by an American company, receives messages from Newfoundland and sends them on to Sydney, using for the latter purpose a powerful battery and the ordinary Morse signals. The second station is worked by the French Trans-atlantic Company, and is furnished with exceedingly delicate receiving instruments, the invention of Sir William Thomson, and used to receive messages from Brest and Duxbury. These very sensitive instruments were found to be seriously affected by earth-currents; ie., currents depending on some rapid changes in the electrical condition of the island; these numerous changes caused currents to flow in and out of the French company's cables, interfering very much with the currents indicating true signals. This phenomenon is not an uncommon one, and the inconvenience was removed by laying an insulated wire about three miles long back from the station to the sea, in which a large metal plate was immersed; this plate is used in practice as the earth of the St. Pierre station, the changes in the electrical condition or potential of the sea being small and slow, in comparison with those of the dry rocky soil of St. Pierre. After this had been done, it was found that part of the so-called earth-currents had been due to the signals sent by the American company into their own lines, for when the delicate receiving instrument was placed between the earth at the French station and the earth at the sea, so as to be in circuit with the three miles of insulated wire, the messages sent by the rival company were clearly indicated, so clearly indeed, that they have been automatically recorded by Sir William Thomson's syphon recorder. nexed is a facsimile of a small part of the message concerning the loss of the steamship Oneida, stolen in this manner [here omitted.] It must be clearly understood that the American lines come nowhere into contact, or even into the neighborhood of the French An line. The two stations are several hundred yards apart, and yet messages sent at one station are distinctly read at the other station; the only connection between the two being through the earth; and it is quite clear that they would be so received and read at fifty stations in the neighborhood all at once. The explanation is obvious enough: the potential of the ground in the neighborhood of the stations is alternately raised and lowered by the powerful battery used to send the American signals. The potential of the sea at the other end of the short insulated line remains almost if not wholly unaffected by these, and thus the island acts like a sort of great Leyden jar, continually charged by the American battery, and discharged in part through the short insulated French line. Each time the American operator depresses his sending key, he not only sends a current through his lines, but electrifies the whole island, and this electrification is detected and recorded by the rival company's instruments. ** * * All owners of important isolated stations should use earth-plates at sea, and at sea only. This plan was devised by Mr. C. Varley many years ago to eliminate what we may term natural earthcurrents, and now it should be used to avoid the production of artificial earth-currents which may be improperly made use of.Nature, May 5th, 1870. 3. Baron von Richthofen's Explorations in China.-The Baron V. RICHTHOFEN, formerly of the Geological Survey of Austria, accompanied Mr. J. Ross Brown to China two years ago, and since then has occupied his time in making geological explorations in China. His investigations have been encouraged by the generous subscription of 16,000 dollars, made by the American merchants of China to aid him in prosecuting such exploration. An interesting feature of this subcription is that he is at liberty to use it as he deems best for the interests of science, without regard to immediate commercial or economic results, and in addition to his geological work, he purposes to institute meteorological observations at several points. Already many important additions have been made to the knowledge of the geology of Northern China and Manchuria. Some of his observations made between Shanghai, and Han-kau were published in the Proceedings of the American Academy of Boston, vol. viii. Since these were written other letters have been received by Prof. J. D. Whitney, from which we hope to make extracts for a future number of this Journal. 4. Thermal Units.-Prof. T. MUIR proposes in "Nature" of April 14th, the introduction of the word therm for a thermal unit, making that unit the quantity of heat necessary to raise the temperature of 1 gram of water from 0° C. to 1° C. Therm, hectotherm, kilotherm would be consequently the expressions for respectively 1,100, 1000 therms, suggestively corresponding to gram, hectogram, kilogram in name as well as in nature." 5. Astronomer at the Cape of Good Hope.-Mr. E. J. Stone, F. R.S., of the Greenwich Observatory, has received an appointment to this position.-Nature, June 23. 6. American Association.-The American Association for the Advancement of Science will hold its next meeting in Troy, commencing on the first Wednesday in August. Prof. William Chauvenet is the President for the year. 7. British Association.-The next meeting of the British Association will be held at Liverpool on Wednesday, the 14th of September, under the Presidency of Prof. Huxley. 8. ADMIRAL RUSSELL HENRY MANNERS, President of the Astronomical Society of London, died recently, aged 70 years. IV. MISCELLANEOUS BIBLIOGRAPHY. 1. A concise analytical and logical Development of the Atmospheric System as God made it; and the Elements of prognostication by which the weather may be forecasted; designed as a Weather-book for the practical mind of the Country; by THOMAS B. BUTLER. Hartford, 1870. 404 pp. 8vo.-This work on Meteorology will be read with profit by all interested in the subject. It presents a large number of facts of the Author's own observations, together with others from various sources, and is illustrated with many woodcuts. The title is calculated to excite a prejudice in scientific minds against the volume, and many would at once substitute for "The Atmospheric System as God made it," "The Atmospheric System as Thomas B. Butler makes it." The subject is too large a one to be discussed in a book notice; and we refer, therefore, to the volume for the views, which, according to the motto on the title page, is, in the author's opinion, "the truth [that] is mighty and will prevail." 2. Synopsis of the Extinct Batrachia and Reptilia of North America: Part 2d. By EDWARD D. COPE.-This second part of Prof. Cope's important work on the Extinct Batrachia and Reptilia of North America includes the synopsis of the remainder of the Dinosauria, the Testudinata, the Pterosauria, the Pythonomorpha, and the Ophidia. The Testudinata are divided into two groups: the Cryptodira, represented by thirty-four species which are referred to fourteen genera, and the Pleurodira, represented by ten species of four genera. Rhabdofelix longispinis Cope is the only known North American representative of the Pterosauria. Of the Pythonomorpha, the author mentions twenty-seven species. Three species of the Ophidia are given. Several additional Reptilian species are remarked upon in the Appendix, and one new genus of the Cheloniidæ is defined. Prof. Cope, through his labors, is throwing great light on the ancient vertebrate life of this continent. 3. First Principles of Chemical Philosophy; by JOSIAH P. COOKE, JR., Erving Professor of Chemistry and Mineralogy in Harvard College. 534 pp. text and 22 tables and index, 12mo.The first part of Prof. Cooke's Chemical Philosophy was noticed in a former volume of this Journal. That portion of the work, it will be remembered, was devoted to the development of the fundamental principles of chemical science. In the second part of his treatise, the author gives a succinct, but very comprehensive, summary of the more important elements and compounds, exhibiting |