INSTRUMENTS, &c. FOR SALE. These Notices, which are restricted to three lines each, are inserted free of charge to subscribers: applications respecting prices and other particulars to be made to the Editor, with a stamped envelope for reply, without which no answer can be sent.-For Advertisements with prices and more complete details, a small charge will be made. N.B.-It is particularly requested that we may be informed when instruments are disposed of, in order that the notice may be withdrawn, and fruitless applications prevented. Achromatic Refractor, 7 in. aperture, 9 ft. focus, by Troughton & Simms; 5 celestial and i terrestrial eye-pieces; on large garden Equatorial stand, with patent steadying rods, &c. [54] Equatoreal Telescope, 5 ft. focus, 4 in. aperture; powers 60, 340, and 450, on extra stout mahogany tripod stand, steadyingrods, levels, large finder, &c., complete. [ 18 ] Achromatic Refractor, 60 in. focus, 4 in. aperture, powers 60, 120, 200, and terrestrial eye-piece; by Goddard: on improved garden stand, with finder, &c., complete; price low. [60] Achromatic Refractor, 4 ft. focal length, 33 in. clear aperture, by Wray; with two celestial and one terrestrial eye-pieces, on garden stand. [46] Achromatic Refractor, 4 ft. focal length, 3 in. aperture, on brass tripod stand, with achromatic finder, 3 celestial and 3 terrestrial eye-pieces, &c. [20] Achromatic Refractor, 4 ft. focus, 23 in. aperture, 3 pancratic eye-pieces, powers 60 to 200, with pillar and claw and garden tripod stand.-Would be sold or exchanged for a larger. [61] Newtonian Reflector, 7 ft. focus, 7 in. aperture, 8 eye-pieces, powers from 30 to 360, Equatoreally mounted. [29] Transit Instrument, 5 ft. focus, 3 in. aperture, Ys fitted with agates, for mounting on stone piers. Equatorial Stand, adapted for a 5 or 6 ft. telescope: 13 in. circles divided on silver, reading to 10" of space and 4s. of time.-Has never been used." [16] [56] [55] Improved Varley Stand, with rackwork movements, adapted for a telescope of 5 or 6 ft. focus: fixed upon a circular turn-table, so as to be easily pointed in any direction. Polar Axis of mahogany, 7 ft. long, adapted for a 4 ft. telescope, with 12 in. circles, reading to minutes. Speculum Grinding Apparatus, capable of working a 7 ft. speculum: with tube and fittings for a 9 in. Newtonian. Brass Orrery and Tellurium (one or both), designed by and formerly the property of the late Dr. Pearson, and purchased by the present owner at his sale of instruments in 1853. [59] Recreative Science: complete in numbers, half-price. [30] [57] FOR OR SALE-an excellent REFLECTING TELESCOPE, focal length 7 ft., aperture 7 inches, mounted so far Equatorially that with a little care it may be turned on a star or planet in the day-time.-Four Eye-pieces.-Price £20 only (less than the cost of the stand), the proprietor having mounted a larger instrument. [11]F INSTRUMENTS, &c. WANTED. Equatorial Stand Wanted-adapted for a 5 ft. Refractor, with graduated circles; second-hand, at a moderate price. [35] Monthly Notices of the Royal Astronomical Society. The third volume wanted: a good price will be given. [26] Schröter's Selenotopographische Fragmente-a copy wanted, in two volumes. PRECESSION OF THE EQUINOXES.-Will any of your - [ 49 ] subscribers be equal to the task, oblige me with a careful calculation of the exact number of years that have elapsed since the Sun entered the constellation Aries on the 21st of March ?-W. E. H. who may ASTRONOMICAL REGISTER. LIST OF SUBSCRIBERS-Names received since our last number. Allison, J. G., Esq., 12 Cumberland Row, Newcastle-on-Tyne Knobell, E. B., Esq., 138 High Street, Burton-on-Trent Locke, W., Esq., Ravensdale, Dundalk, Ireland Mills, E. B., Esq., 4 Hartland Terrace, Bude, Cornwall We can in no case insert communications from correspondents with whose names and addresses we are unacquainted. On "Jupiter's Satellites," by E. J., in our next. On "Observing Seats," a paper is in preparation by T. W. and others. The Astronomical Register is intended to appear at the commencement of each month; the Subscription (including Postage) is fixed at Three Shillings per Quarter, payable in advance, by postage stamps or otherwise. The pages of the Astronomical Register are open to all suitable communications: Letters, Articles for insertion, &c., must be sent to the Editor, Mr. S. GORTON, Stamford Villa, Downs Road, Clapton, N.E., not later than the 15th of the month. The Astronomical Register. No. 35. NOVEMBER. 1865. SCHWABE ON THE SUN. IN No. 1521 of the Astronomische Nachrichten, Schwabe gives a summary of what is to be seen on the sun; he carefully refrains, however, from all speculations as to causes. 1. Spots with penumbra, having a distinct, dark, sharply defined, angular nucleus, surrounded by a penumbra, the indentations in which generally correspond with those in the nucleus. 2. Spots with a distinct but indeterminate outline and no penumbra. These only occur in groups. 3. Punctulations, shapeless masses, not surrounded by a penumbra, which may be made out with a good 2-ft. telescope. They generally occur in solitary, and sometimes in double patches. He names them Nebenpunkte when they surround a solitary spot, and Zwischenpunkte when they occur between two spots. 4. Pores. These he finds to be generally connected together by short lines, and where very numerous they form dull grey spots. They are rather more distinctly seen in the penumbræ, and especially in what he calls Nebel-large grey irregular patches, often of large extent, and generally intersected by rows of punctulations and single spots destitute of penumbra. The periodicity of the spots he estimates "provisionally" at ten years. The spots, especially when in large groups, he finds to increase, as a rule, like the groups themselves, on the Eastern, and to decrease on the Western side. The isolated spots, or those which are surrounded by few Nebelpunkte, are less variable in their form. CORRESPONDENCE. N.B. We do not hold ourselves answerable for any opinions expressed by our correspondents. BINARY STARS. TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,-Will you allow me to correct a slight oversight on my part in the notes to my Double Star Measures in the October number of the Register? The concluding sentence in the note on n Orionis should be referred to the following star, 2 Orionis. The former star was measured both in position and distance on two evenings, but in the case of the latter the state of the atmosphere would not allow of distance measures being taken on the second occasion on which it was observed. I am, Sir, yours faithfully, Woodcroft Observatory, Cuckfield : GEORGE KNOTT. October 16, 1865. LUNAR OBSERVATIONS. TO THE EDITOR OF THE ASTRONOMICAL REGISTER. Sir,-As lunar observations appear to be increasing in interest, and, in addition to the notices occasionally inserted in the Register, I am favoured with various communications, in which I perceive new features are brought to light, it is probable that the following table of the craters and rings on the surface of the Mare Crisium, already known, may not only interest your readers, but be of service especially to those observers who, having telescopes of large aperture, may desire to scrutinise the surface of the Mare. I am, Sir, your obedient servant, Victoria Observatory, 42 Sewardstone Road West, Notes on the Table of Lunar Craters. W. R. BIRT. Nos. 3, 4, and 16. The symbols of these craters are queried, as the positions of the craters require to be more accurately ascertained. No. 21. A crater further E. of this, also on the E. branch of Schröter's forked ridge, was suspected by Messrs. Knott and Birt on October 5, 1865. Nos. 29 to 34 inclusive have not been symbolised, as further observations are requisite to fix their localities. It is also uncertain whether any of these may be among the five mentioned by B. & M. in the region near I Ca1, IC 23, as having been discovered by them after the publication of this part of their large map. The letters e to k refer to an unpublished drawing, obligingly furnished by the Rev. W. R. Dawes. No. 35 seen only when very near the Terminator. |