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be seen from the fact the R. A. on January 8 might have been between 7 h. 35 m. and 10 h. 29 m. The space to be examined was divided between Paris, Marseilles, Berlin, and Pola. On the 2d of March, Palisa, of Pola, after having mapped 2800 stars, detected the missing asteroid.
Lumen, 141, was independently discovered by Watson and Borelly in August, and Athor, 161, in Oct., by Palisa. The column "No." gives the current number of each astronomer's discoveries.
THE MOON. Professor Newcomb, of Washington, has published an investigation of corrections to Hansen's tables of the moon, with tables for their application, forming Part III. of papers printed by the United States Transit of Venus Commission. The object of the memoir is to aid in the reduction of the occultations observed by the various parties for longitude.
In this paper is announced the discovery of an inequality in the longitude of the moon, which has a period of 27.4 days. It can be put in the form
dv=+1.5" sin. [9+21.6° (Y-1865.1]), g being the mean anomaly.
This term was deduced empirically from a discussion of corresponding Washington and Greenwich observations. More recently Neison, of England, has given an account of some lunar perturbations produced by Jupiter, and has shown that these gave rise to a new periodical term in the moon's longitude, which could be expressed by
èv=+1.163" sin. [9+20.85° (Y—1864.4)].
From this it follows that we have to do with a real inequality theoretically deduced by Neison. The agreement between the theoretical and Newcomb's empirical term is a satisfactory one. The two independent results confirm each other and dispose of the doubts expressed as to the reality of this term.
The numerical lunar theory of Sir G. B. Airy is in a forward state, and one section of it is to be printed as an Appendix to the forthcoming volume of Greenwich observations.
Dr. George W. Hill, of the American Ephemeris, has recently printed (privately) an exhaustive treatise on that part of the motion of the lunar perigee which is a function of the mean motions of the sun and moon. From this work we learn that its author is also engaged in other researches in the lunar theory, which are shortly to be published. This work of Dr. Hill has met with a most cordial appreciation abroad from Professors Cayley and Adams. The latter confirms its principal conclusions from unpublished researches of his own.
In a recently published pamphlet on astronomy in Rome during the pontificate of Pius IX., Secchi gives an account of his unpublished observations on the lunar surface.
Professor Alexander, of Princeton, has brought forward a variety of evidence tending to indicate some envelope, like an atmosphere, for the moon. This evidence was principally drawn from observations during eclipses.
The work of Professor Newcomb on the Lunar Theory, after suffering an interruption of some years, was recommenced in 1876. That part of it which consists of a new reduction and examination of all recorded eclipses and occultations of value before 1750 is substantially complete, most of it being in the hands of the printer. The ancient observations which have been considered most reliable indicate a correction of more than half an hour to the times of ancient eclipses as hitherto calculated from the tables. This correction so changes the computed paths of the moon's shadow during total eclipses that the chronological questions involved in them will no doubt have to be re-examined. The most remarkable result of the research is that the motion of the moon during the past 250 years may be very
closely represented by the alteration of a single term in Hansen's tables. The question whether this alteration is admissible in the theory cannot yet be decided.
COMETS. The recent dearth of comets has been supplied in 1877 by the discovery of five. Comet a was discovered by Borelly, of Marseilles, on February 8, and was visible as a telescopic object till March 18 in Europe, but was observed by the 26inch telescope at Washington so late as March 30. It had the usual comet spectrum. Comet b was discovered by Winnecke, of Strasburg, on April 5. Young, of Dartmouth, and Wolf, of Paris, have investigated its spectrum, which is of the usual type. Comet c was discovered by Swift, of Rochester, on April 10, and independently by Block, of Odessa, on the same date, and by Borelly on the 14th. Comet 6 remained a tolerably bright object until some time in July. Comet c was always faint. There is a strong resemblance between the elements of comet c and those of the comet of 1762, but the researches of Holetschek indicate that these are different bodies.
D’Arrest's comet was found by Tempel, of Florence, in the place indicated by Le Veau's ephemeris.
Comet e was discovered by Coggia, September 13, and f by Tempel, October 2.
In regard to comet b, 1877 (Winnecke's), the discoverer has remarked that a similarity exists between its elements and those of comets II. 1827 and II, 1852. The intervals 1827–52 and 1852–77 being equal (twenty-five years) lends additional strength to the supposition of identity. This question is remarked upon by Hind in Nature. (April 19), who says: “The case is a very curious one, and possibly unique of its kind : similarity of elements at three epochs separated by very nearly equal intervals; and on the assumption of a corresponding period of revolution, a very near apparent approach to the planet (Jupiter) which so greatly disturbs the cometary orbits; yet action to account for outstanding differences of elements could not have taken place on either occasion of the comet's passage through that part of the orbit where great perturbation would be looked for."
The Annals of the Moscow Observatory (Vol. III., Part I.) contains an important paper by Bredichin on the anomalous forms in the development of the tails of comets, with especial reference to comet II. 1862, and a reduction by Gromadski of meridian observations of fundamental stars by Bredichin and Khandricoff. The results of the first of these papers have been published in the Astronomische Nachrichten.
Dunér publishes in the Proceedings of the Stockholm Academy, 1876, No. 1, a paper on Coggia’s comet of 1874, accompanied by nine drawings.
SPECTROSCOPIC OBSERVATIONS. No publication in regard to photographic spectra of stars has been made by either Dr. Huggins or Dr. Draper since the first announcement of their preliminary results. It is understood that the observation of the spectra of fixed stars will be a principal work of the new observatory of Princeton College.
Dr. Konkoly, of the O'Gyalla Observatory, in Hungary, has recently communicated the result of his observations on the spectra of 160 fixed stars to the Hungarian Academy of Sciences. The bright bands in the spectrum of Beta Lyrce, found by Vogel in 1871, and previously by Secchi, are now wanting
Secchi publishes a list of 444 colored stars from Schjellerup's list and his own observations, with notes on their spectra, etc. It is noteworthy (and little known) that Sir William Herschel recognized the essential differences of the first three types of Secchi so early as 1798. (See Phil. Trans., 1814, page 264).
The change of spectrum of Nova Cygni is noticed in another place.
ZODIACAL LIGHT. From information received from Mr. H. C. Lewis, of Germantown, we learn that he continues to see the zodiacal light from horizon to horizon, and also that the veritable Gegenschein, as an oval spot of light in the zodiacal light, appears distinctly, and from month to month shifts its place in the stars so as to keep about opposite the sun.
In the Comptes Rendus for July 2, Hugo has a note on a luminous column vertically extended above the moon, and some four degrees in length; and Trouvelot has recently published in the Proceedings of the American Academy a note on a similar phenomenon, under the caption “The Moon's Zodiacal Light.” In the Paris Memoirs, 1771, p. 434, Messier describes a similar phenomenon, which has never yet been explained, and gives a wood - cut of its appearance.
TIME. One of the few ways in which astronomy can make itself practically valuable to the community at large is in the dissemination of standard time to navigators and to men of business. The following notes refer to what has been done in this direction during 1877.
The recent invention of Barraud and Lund, of London, for controlling a clock by automatic or other signals is described in an advertisement in the Telegraphic Journal for May, 1877. It has the capital advantage over the Bain system that the clock may run either fast or slow without affecting the control. It suffices to control a clock whose rate is +2 minutes daily. It appears to be a suitable device for the regulation of the clocks of manufactories, railways, churches, etc., where a control to the nearest minute is all that is required, and where economy is necessary. In this connection it may be noted that the Paris Observatory now controls the clocks of the Conservatoire, St. Sulpice, and the Luxembourg, and the system is to be extended to the clocks of the various cab-stands, which will be a very practical and valuable step.
The public clocks of Vienna are controlled by a pneumatic-motor clock which is said to have been very satisfactory.
The Trinity House of England is adopting gun-cotton as a means for fog-signals, and it may prove a valuable substitute for the time-guns now established in the various ports of the world in cases where the sound only is available for sig. nals. Where the flash can be observed a gun is preferable, or an electric light, as used at Melbourne.
Redier describes in the Comptes Rendus a simple device for correcting the going of clocks for changes in rate due to changes of atmospheric pressure, by means of a small aneroid barometer fastened to the pendulum bob.
The Naval Observatory of Washington has been for some