THE AUTHOR'S OBSERVATORY.

THE drawing opposite represents a sectional view of the author's Observatory, Southampton, with the instruments in situ. It will be observed that the polar axis and transit-circle rest on stone supports; the floor is detached from these, so that the stability of the instruments is not affected by movements on it. The clock is fixed on the north side of the support of the higher end of the polar axis; a side view of it is presented in the drawing. The walls are of weather-boards

of an inch thick, overlapping each other 1 inch, and the roof is covered, outside the boards which compose it, with canvass, which having received a thick coating of paint, and having been nailed on in a moist state, has been found impervious to rain; the method of opening the shutters of the transit-room will be apprehended from the drawing-they are counterpoised by weights on the opposite side of the building; the shutters of the dome are closed, but the counterpoise is shewn on the roof to the right. The position-wire micrometer is fixed on the telescope, and the handle giving motion in declination is attached to the tangent-screw. When the shutters of the dome are open, the dome may be

turned round towards the object to be viewed, and may be made to follow it by an advance westward from time to time. The observing-chair may be remarked in the drawing-its position is between the two upright supports of the transit-circle.

The building consists of two compartments, the equatorial-room and the transit-room: the former is nine feet in diameter, in the form of a duodecagon, the roof is nearly circular; the shutters opening in the side increase from 9 inches to 2 feet 6 inches in width. The lower curb of the roof and the upper curb of the wall are fitted with cast-iron plates, between which are the four-inch cannon-balls which support the roof and enable it to revolve. The telescope is mounted with a polar axis having the usual adjustments: the right ascension and declination-circles are each fifteen inches in diameter, and read off, the one to four seconds of time, the other to one minute of space. The shutters of the transit-room run along the ridge of a sloping roof, which is held together by iron hoops extending across the slit; these admit of being turned round so as not to interfere with distinct vision.

Before the foundation was laid, the ground was excavated to the depth of 18 inches, and filled up with concrete; on this, brickwork was raised six inches above the ground. An oaken curb is laid on the brickwork, into which are inserted uprights of 21⁄2 inches by 2, and 6 feet in height. These are united at the top to a corresponding curb, and outside of these are nailed the weather-boards forming the walls. Though simple in its arrangement, this Observatory was constructed after the pattern of some of the most approved private ob

servatories in the kingdom, which the author inspected carefully before setting to work.

For a description of the instruments, for specimens of the mode of registering observations, and of the accuracy with which results may be obtained by the application of corrections for minute instrumental deviations, the paper at the end of the work may be advantageously consulted.

For the last five years a complete set of meteorological observations have been taken daily at the Observatory, the results of which have been published from time to time in the Registrar-General's Quarterly Reports.

To guide the judgment of such as may be disposed to establish an observatory of similar pretensions, the expense of the building and instruments is here given. Building, exclusive of the stone piers of the instruments, 50%.; transit-circle and two collimators, 2107.; 5-feet equatorially-mounted telescope by Dollond, 1607; clock, 40%.; micrometers, artificial horizon, &c., 25l.; meteorological instruments, 127. 128. These are the prices which would be charged by the best opticians in London, whose names would be a warrant that the instruments were excellent of their kind.

The author's humble, but he hopes not useless, labours have now been brought to a conclusion. He trusts that his time has not been misemployed in simplifying astronomical science—an object which has engaged the attention of such eminent men as the Astronomer Royal, Professor Arago of Paris, and M. Quetelet of Brussels, who have not disdained to write elementary treatises similar in their tendency to the present.