Hence for small observatories other forms of revolving roof are desirable, and quite the easiest and cheapest contrivance is that embodied in the “Romsey” type of observatory, devised half a century ago by that accomplished amateur the Rev. E. L. Berthon, vicar of Romsey. The feature of his construction is an unsymmetrical peak in the revolving roof which permits the ordinary shutter to be replaced by a hinged shutter like the skylight in a roof, exposing the sky beyond the zenith when open, and closing down over a coaming to form a water tight joint. Berthon’s original description of his observatory, which accommodated a 9¼ inch reflector, may be found in Vol. 14 of the _English Mechanic and World of Science_ whence Fig. 179 is taken. In this plate Fig. 1 shows the complete elevation and Fig. 2 the ground plan, each to a scale of a eighth of an inch to the foot. In the plan, _A,A_, are the main joists, _P_ the pier for the telescope, T that for the transit, and _C_ the clock. Figs. 3, 4, and 5 are of details. In the last named _A_ is a rafter, _b_ the base ring, _c_ the plate, _d_ one of the sash rollers carrying the roof, and _e_ a lateral guide roller holding the roof in place. The structure can readily be built without the transit shelter, and in fact now-a-days most observers find it easier to pick up their time by wireless. The main bearing ring is cut out of ordinary ⅞ inch board, in ten or a dozen, or more, sections according to convenience, done in duplicate, joints lapping, and put very firmly together with screws set up hard. Sometimes 3 layers are thus used. The roof in the original “Romsey” observatory was of painted canvas, but rubberoid or galvanized iron lined with roofing paper answers well. The shutter can be made single or double in width, and counterbalanced if necessary. The framing may be of posts set in the ground as here shown, or with sills resting on a foundation, and the walls of any construction—matched boards of any kind, cement on wire lath, hollow tile, or concrete blocks. Chambers’ _Handbook of Astronomy_ Vol. II contains quite complete details of the “Romsey” type of observatory and is easier to get at than the original description.