APPENDIX.

REPORT OF THE OBSERVING ASTRONOMICAL SOCIETY.

OBSERVATIONS MADE BY THE MEMBERS.

Solar Phenomena.-Mr. T. G. E. Elger, F.R.A.S., reports that "on August 19 many large scattered groups of spots were observed. The most remarkable of them measured, at 3h., about 2′ 56′′ in extreme length : the penumbra, which was very irregular in shape, contained upwards of one hundred small black spots. During the month of September no large groups were remarked. On the 7th the sun was quite free from spots, with the exception of four small punctures without penumbra; and on the 18th the large groups of August 19 had diminished to such an extent that they were scarcely deserving of notice. The portion of the sun's disc which had been occupied by the large spot of August 19 was near the W. limb on September 17, and was observed to be of an intensely brown colour; this appearance was frequently remarked in connection with the large groups of last year." Mr. T. W. Backhouse writes: "My only September observation of the sun worth mentioning is that, on the 20th, when there was a largish spot on the middle of the S. zone, its umbra was of a singular shape; at 3h. 10m. it was 23,000 miles long, but half the length consisted of a very narrow, straight projection, and it was 9,500 miles wide. Its penumbra was only 29,000 miles long.

Meteors.-On September 10, 7h. 4m., "while daylight was too strong for the visibility of any stars," the Rev. S. J. Johnson, of Crediton, witnessed the appearance of a meteor of considerable brightness. He says, "It started about 25° above the S. horizon, and after taking a diagonal course ended at an altitude of about 10°. It continued in sight about 5 seconds." The meteors of August were well observed by Mr. E. Neison, of London, who, with the assistance of two friends, obtained the following results :—

Mr. Neison remarks that the total observable meteors were without doubt over 500, as only about one-half of the sky was kept under view. Cotham Park, Bristol : WILLIAM F. DENNING, November 7, 1871. Hon. Sec.

Aurora Borealis.-On the evening of November 9, Mr. William F. Denning observed a very interesting, though not very grand, exhibition of the Aurora Borealis. He first noticed the phenomenon at 7h. 30m., when there was a large arch of auroral light extending from places about 45° east and 45° west of the northern horizon, and passing just below Beta Aurigo, through Ursa Minor, over the star Gamma, and on through the head of Hydra, enveloping the stars Beta and Gamma in that constellation. The light was most intense in the N.W. and N.E. Many changes were apparent in the intensity of this arch, and it soon appeared to be broken, and gradually became fainter, until at 7h. 57m. all traces of it were gone. I noticed no streamers at all, but at the time when the phenomenon was at its best, an intense glow was suffused over the northern horizon. Much later in the evening, and indeed throughout the greater portion of the night, this glow was still apparent through breaks in the stratus clouds that were situated in proximity to the northern part

of the horizon.

The Nebula in the Pleiades in Taurus.-Mr. Albert S. Holden reports that" with good eyesight and a clear atmosphere I have failed to find the slightest traces of the nebula on all occasions; I have, therefore, no hesitation in saying that in instruments of 3-in. aperture and under this object is utterly invisible. I beg some members of the Society to search for this object with larger instruments, so that the question as to its actual disappearance may be beyond dispute. It is important that this question should be set at rest at once, because in the event of the nebula brightening we should certainly regret not having decisively established the fact of its disappearance." There are several well authenticated instances of change noticed in regard to some of the nebulæ, and it is very advisable the object spoken of above should be very carefully looked for by those who possess telescopes of greater power than Mr. Holden.

HACKNEY SCIENTIFIC ASSOCIATION.-At the First Ordinary Meeting of the Fifth Session, held on November 14, a large audience assembled to hear a paper by the distinguished selenographer, Mr. W. R. Birt, F.R.A.S., V.P. of the Association, "On the Progress of Selenography during the last Half Century."

Mr. Birt, taking as his starting point the year 1821, remarked that previous to that epoch few observers had devoted much attention to the description of detail of the moon's surface. We have, he said, some good drawings of Bianchini, aud a valuable series by Schröter, which, with the letterpress of his "Selenotopographische Fragmente," constitute an important store of facts for continual reference. It was about the commencement of the last half century that Lohrmann took up selenographical work, and produced in the year 1824 four of his sections on a connected scale, which in this respect differs materially from Schröter's plan. He also introduced what may be termed the "German style," by attempting to depict hypsometrical and chromatic relations by a species of contouring and shading. Perhaps in the latter he has been the most successful, because in the absence of anything like a datum level on the moon, and the large scale that is necessary for delineating relative contours, an attempt to depict relative heights must be unsatisfactory. Nevertheless, his sections contain most valuable information, and have certainly con

Appendix.-Hackney Scientific Association.

3

tributed to the advancement of our knowledge. The great feature of the half century is, undoubtedly, the production of the large German Map, a monument of the skill and industry of its authors, Beer and Mädler. The accurate determination of points of the first order, the approximate position of points of the second order, the accompanying letterpress "Der Mond," containing an admirable introduction to selenography, with records of observations, measurements, and formulæ, render it desirable that its perusal and study should not be restricted to German scholars, but that it should appear in an English dress. So small a portion of the attention of physicists had previously been devoted to lunar subjects, that the great work of Beer and Mädler was considered as well nigh exhaustive; in fact, there was at that time scarcely an astronomer who could or would have immediately followed up, with the energy and perseverance of the authors, a work but little understood, if we except the present Director of the Observatory at Athens, Julius Schmidt. The consequence has been a retardation of progress; for we find nothing of any moment published as illustrative of selonography between the years 1836 and 1852, when the British Association appointed a Committee for obtaining drawings of conspicuous objects, with a view to determine the effects of light upon the appearances as seen at morning, midday, and evening; and also to ascertain the relations existing between the ejected matter of the so-called craters and surrounding ramparts, supposing them to have been produced by falling ejected matter from the central orifice. In connection with this Committee three views of the Mare Crisium were published by Professor C. Piazzi Smyth, and drawings made of the walled plains Plato and Gassendi, by Professors Challis and Philip.

In the year 1856 Julius Schmidt published his “Der Mond," an interesting and useful work, containing comparisons between terrestrial and lunar forms, with sections, and other important information. This work is not much known in this country, and Mr. Birt remarked, in passing, that the small share in selenographical discovery which had fallen to English astronomers, may be attributed to the paucity of works on the physical features of the moon's surface, in the English language. Had a digest, in English, of the principal German works appeared, no doubt attention to a much greater degree would have been given to the moon. Three years later than the publication of Schmidt's work, the Rev. T. W. Webb's "Celestial Objects for Common Telescopes appeared, and there can be little doubt that this unpretending volume has contributed in no small degree to create an interest in lunar studies; containing as it does an excellent index map, a catalogue of named objects, and several most interesting notices of the larger formations.“ An immediate consequence of this portion of Mr. Webb's work was the contrivance of a method by which every object on the moon's surface may be permanently registered; and in the year 1863 a register of lunar objects was commenced. In order to carry out the plan more extensively, a Committee was appointed in the year 1864 by the British Association to superintend the registration, and to map on a large scale the objects observed in its progress. This Committee has mapped three areas of 25 square degrees each, and a fourth has since been issued by private subscription. In addition, two monograms have been issued; one of the Mare Serenitatis, the other of Hipparchus. The number of objects, at present registered is about 2,000, and nearly 500 are named up to the period of the commencement of this work; the study of the moon treated more as a whole, but it is now beginning to be understood that for real progress the separate study of selected portions is necessary, and amateurs

are steadily at work-some in studying the larger craters, others the minute objects, clefts, etc.; and others are engaged in adding to the objects already registered. Should the mode of registration be generally adopted, it will add greatly to the precision of our knowledge of the moon's surface.

The paper closed with a reference to the author's discussion of the observations of Plato, as illustrative of the advantages to be derived from the careful study of a single object, not only as to a knowledge of its principal features, but also of those agencies which have contributed to mould and modify those features; and in expressing a hope that we are now on the eve of becoming acquainted with changes in those features that are evidences of still existing activity, either of a volcanic or meteorological character, or possibly of both.

The paper was listened to with marked interest and attention; and at its close a cordial vote of thanks was moved to the eminent lecturer.

APPENDIX.

REPORT OF THE OBSERVING ASTRONOMICAL SOCIETY.

OBSERVATIONS MADE BY THE MEMBERS.

Jupiter.-Mr. H. W. Hollis, of Newcastle, Staff., reports that on January 14, 9h, the disc of the planet appeared very sharp, and he counted 22 different bands of colour. "Those visible in the equatorial parts of a beautiful delicate pinky brown. I am certain that the belts are visible up to the very edges of the disc, but there is an apparent increase of brightness for a considerable distance round the edge of the planet, probably an effect of contrast, which obliterates the extremities of the belts unless carefully looked for. Several well marked and beautifully defined irregularities in the belts showed the rotation most clearly even in half an hour's watching, Jan. 23, 8h. 15m. Satellite I. just entered on disc of Jupiter and appears as an intensely white spot. 9h. 20m., shadow of I. on centre of disc, black and sharply circular, the satellite itself cannot be seen." Mr. T. W. Backhouse, of Sunderland, observed the transit of satellite I. on Jan. 14. At 13h. 54m. it "appeared as a faint white spot." On Feb. 3, 6h. 7m., he examined satellite III., and its shadow when in transit. The satellite itself was, at the time mentioned, nearly half across Jupiter on a darkish belt. "It is much darker than the darkest part of the planet." At 7h. 30m., it was "still very plain, but only the same shade as the darkest part of Jupiter. It was smaller than its shadow which was very black."

T. Corona Borealis.-Mr. T. W. Backhouse says:-"A change has taken place in this star. On its fading for the second time it became stationary in brightness about the middle of the year 1867, since which time, up to the beginning of this year, it continued the same, but with frequent slight fluctuations, which, however, ceased so far as I could judge, at the end of 1869. I have suspected fluctuations since 1869, but they were doubtful. On Jan. 14, this year, I looked at the star and found it about its usual brightness, or, perhaps, a little fainter, but certainly not fainter than it had been at times previously. I did not look at it again till March 5, when I found it much fainter than I ever saw it before, perhaps Half a magnitude less than usual, and it was the same on the following day."