"Lohrmann's Map of the Moon consists of 25 sections on the scale of 37.5 inches to the moon's diameter, or the same scale as Beer and Mädler's Mappa Selenographia.' They have been engraved at different times on copper-plate, and are in every respect perfectly analogous to the four original sections which were issued in 1824. They have been carefully edited by the well-known selenographer Herr Julius Schmidt, of the Observatory at Athens, and are a faithful reproduction of the original ink maps of Lohrmann, so that in the present map we have an exact representation of the surface of the moon as it appeared to Lohrmann during the period 1821-27. On this account, therefore, the map will form a most valuable contribution to selenography. In his capacity of editor, Schmidt has added to the map all the standard names of Beer and Mädler. He has also named a number of additional points."

Schmidt's great map of the moon has not reached this country, so far as we know.

Professor Newcomb, of Washington, has an important note in Silliman's Journal (November) on the mean motion of the moon. It is an abstract of the researches which have been published in full in Wash. Ast. Obs., 1875.

He has made a discussion of all trustworthy recorded observations of the moon before 1750-eclipses and occultations. These materials are:

1. Ancient eclipses (total) of the sun, such as the celebrated ones of Larissa, etc. Professor Newcomb comes to the con

clusion that the accounts which remain to us are in no one case sufficient to connect the eclipses computed back from modern data with the phenomenon recorded by the historian. In many cases it is not even certain that this phenomenon was an eclipse at all.

2. The nineteen eclipses of the "Almagest" give data which are at the best uncertain.

3. The eclipses of the Arabian astronomers, which are now for the first time utilized.

4, 5, 6. The observations of Tycho Brahe, etc., of Gassendus and Hevelius, are not valuable for this purpose, as they were taken without the aid of telescopes, and are not of sufficiently ancient date.

7. The observations of De la Hire, De l'Isle, and others, from 1672 to 1750, are now discussed for the first time, and prove to be most valuable material. From 1750 to 1860 or 1865, Hansen's tables represent the observations well. The whole series is represented by omitting the empirical terms of Hansen depending on eight times the mean motion of Venus. The value of the acceleration from observation alone is 8.8", Hansen's adopted value being 12.17". This value 8.8", however, requires to be changed by -0.9" in a century to satisfy observations, and there are several ways in which this may be effected. The rotation of the earth may not be uniform, the analytical theory may not be complete, or other and undiscovered bodies may enter in. A term expressing the total correction to Hansen's tables is deduced and provisionally adopted. Its theoretic basis requires further investigation. Dr. Haughton has considered these ancient eclipses in a memoir read to the British Association. Dr. Weiler has also a series of papers on the theory of the secular acceleration in the Astronomische Nachrichten, No. 2060 et seq.

In 1787 Sir William Herschel announced that he had observed three volcanoes in active operation in different parts of the moon, the diameter of the principal crater being about three miles. In May, 1877, Dr. H. J. Klein, of Cologne, while examining the moon, noticed a great black crater on the Mare Vaporum, and a little to the northwest of the wellknown crater Hyginus. He describes it as being nearly as large as Hyginus (or about three miles in diameter), as being

deep and full of shadow, and as forming a conspicuous object on the dark gray Mare Vaporum. Having frequently observed this region during the last twelve years, Dr. Klein felt certain that no such crater existed there at the time of his previous examinations. He communicated his observations to Dr. Schmidt, of Athens, who assured him that this crater was absent from all his numerous drawings of this part of the lunar surface: neither is it shown by Schröter, Lohrmann, or Mädler. Dr. Klein made his discoveries known generally, and they seem to have been partially confirmed by other observers. The Mare Vaporum, in which the new crater is situated, lies close to the centre of the visible surface of the moon, so that objects in this region are very slightly affected by the lunar librations. It is also a part of the moon which has been most carefully studied. Had this new crater of Dr. Klein's appeared in a less well known region, much more doubt would have been felt as to whether it had previously existed or not.

COMETS; METEOR STREAMS.

The comets of 1878 have been

Comet I., discovered July 7, by Lewis Swift, of Rochester, N. Y. This comet was only observed in America by Dr. C. H. F. Peters, the majority of American observers being in the West on eclipse expeditions. It is probably identical with a comet discovered by P. Ferrari at Rome in July. On July 20, Tempel's periodic comet was found by Winnecke, quite away from its ephemeris place.

Orbit of Comet IV., 1873.*-M. Raoul Gautier, of Leipsic, has discussed all accessible observations of this comet, extending from August 20 to September 20, and, though the period of visibility was not long, the data make it tolerably certain that the orbit is elliptic, the sum of the squares of the residuals being reduced from 81.18 on the hypothesis of a parabola to 2.14 on that of an ellipse, while the probable error of an observation is reduced from 6.04" to 1.14". The eccentricity of the ellipse is, however, very large, corresponding to a period of revolution which may perhaps range from 3000 to 3600 years, so that this comet is to be classed among those of very long period.

*Astronomische Nachrichten, No. 2164.

One of the most important papers of the year is by Professor Newton, of Yale, on the "Origin of Comets." It is impossible to give here an abstract of this paper, which is itself a series of propositions, each in a condensed form, and each closely connected with every other. We can only refer to this as a body of doctrine which will become the Principia of this subject.

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In the Monthly Notices, R. A. S. (1878, May, p. 369), Professor A. S. Herschel has a List of Known Accordances between Comets and Observed Meteor Showers," which will be useful. Seventy-one such are noted.

Encke's comet was found on August 3, by Mr. Tebbutt, of Windsor, N. S. W., with a 44-inch telescope. The comet was 2' in diameter, and pretty bright.

ZODIACAL LIGHT; METEORITES.

The "Results of Observations of Shooting-Stars from 1833 to 1875," by the late Dr. Heis, of Münster, has been published. It comprises Dr. Heis's own observations for forty-three years at the observatory of which he was director. According to Nature, it gives the times of occurrence and the points of first and last appearance of 13,000 meteors, followed by a partial discussion of the results, and catalogues of radiant points.

The zodiacal light continues to be observed by Mr. Henry C. Lewis, of Germantown, Pa.

NEW OBSERVATORIES, NEW INSTRUMENTS, ETC. Accounts of European and American observatories are given elsewhere.

A new private observatory has been founded in Providence, R. I., by Mr. George A. Seagrave. The building is of brick, with a wooden dome. The principal instrument is an equatorial refractor of eight inches aperture, from the workshops of Alvan Clark & Sons. The tube of the telescope is made of sheets of steel riveted together so as to form two conical halves, to insure rigidity. The mounting is unusually heavy for an instrument of this size. The circles for indicating the position of a heavenly body in space are conveniently graduated on their outer edges for roughly finding an object. The declination circle reads by its verniers to 15", and the hour

circle reads to 2" for locating it. The telescope is provided with a position micrometer by the Clarks, and a double-image micrometer by Browning, of London, for the purpose of exact measurements. There are two spectroscopes by Browning and Grunow. The observers are Mr. Seagrave and Mr. L. Waldo, of Harvard College Observatory. From an account of the observatory it is learned that the observers contemplate prosecuting two plans of work. "One of these researches is the measurement of such of the close double stars discovered by our distinguished fellow-countryman S. W. Burnham, Esq., of Chicago, as we can reach with our optical means. The second research is the continuous and exhaustive measurement of one or two stars which have shown unusually large annual motions in the heavens, to determine, if possible, their parallax."

In the list of papers read to the Scientific Association of the Johns-Hopkins University, and as yet unpublished, the only one relating to astronomy is by Dr. C. S. Hastings, "On a True Criterion for Color-Correction in the Astronomical Objective." The formulæ arrived at have been put to a practical test by Dr. Hastings in the making of a 4-inch object-glass.

A commission appointed by the French Chamber of Deputies has reported favorably on the erection of a large observatory at Meudon. The credit given is 690,000 francs ($138,000), of which $78,000 are for the purchase of a large refractor. M. Janssen will be, as before, the director.

Mr. Lockyer has published in Nature a series of articles. on the "Modern Telescope," which gives a useful and convenient popular summary of the principal defects and advantages of the telescopes now in use. The paper by Mr. Grubb on the same subject is taken as a basis, and some of the difficulties described by Mr. Grubb are considered.

Mr. Henry Bessemer, in considering these difficulties, has been led to propose (Nature, January 24, 1878) a plan for overcoming the difficulties in mounting and figuring large glass reflectors, according to which plan he is now making a 504-inch silvered glass reflector. First, as to support: a ribbed casting of iron 52 inches in diameter and 13 inches thick, weighing 1400 pounds, is to be made and annealed in oil. Its face will be turned to a true plane, and a spiral groove one sixteenth of an inch deep and wide will be cut all over this