The arm D E is fixed on the sliding bar F, and may be raised or depressed to any height within its limits. The main pillar a b is fixed in the box b e, and by means of the brass foot d is screwed to the mahogany pedestal X Y, in which is a drawer containing all the apparatus. O, a milled-headed screw, to tighten the bar F when the adjusting screw c g is used. p q is the stage or plate which carries the objects; it has a hole at the center n. G, a concave mirror, that may be turned in any direction, to reflect the light of the candle, or the sky, upon the object. A LIST OF THE APPARATUS TO CUFF’S DOUBLE-CONSTRUCTED MICROSCOPE.[33] [33] This microscope is made oftentimes with a joint at the bottom of the main pillar at _e_, to admit placing the instrument into any oblique situation, and connected to the bottom of a mahogany chest; on which account, it is by some of the instrument makers called the Chest Compound Microscope. EDIT. H, a convex lens, to collect the rays of light from the sun or a candle, and condense them on the object, or to magnify a flower or other large object placed upon the stage. L, a cylindrical tube, open at each side, with a concave silver speculum screwed to the lower end h. P, the slider-holder; it consists of a cylindrical tube, in which an inner tube is forced upwards by a spiral spring, it is used to receive an ivory slider K, which is to be slid between the plates h and i. The cylinder P fits the hole n in the stage: the hollow part at k is designed to receive a glass tube N. R is a brass cone, to be put under the bottom of the cylinder P, to intercept occasionally some of the rays of light. S, a box containing a concave and a flat glass, between which a small living insect may be confined; it is to be placed over the hole n. T, a flat glass to lay any occasional object upon; there is also a concave one u, for fluids. O, a long steel wire, with a small pair of pliers at one end, and a point at the other, designed to stick or hold objects; it slips backwards and forwards in the short tube o; the pin p fits into an hole m, in the stage for that purpose. W, a little round ivory box, to hold a supply of talc and rings for the sliders. Z, a hair brush, to wipe any dust off the glasses, or to take up by the other end a drop of any liquid. V, a small ivory cylinder, that fits on the pointed end of the steel wire O; it is designed for opake objects. Light-coloured ones are to be stuck upon the dark side, and vice versa. Y, a common magnifying glass for any occasional purpose. M, a fish-pan whereon to fasten a small fish, to view the circulation of the blood: the tail is to be spread across the oblong hole at the small end k, and tied fast by means of a ribband fixed thereto; the knob l is to be put through the slit made in the stage, and the tail may be brought under the magnifier. X is a wire to clean the glass tubes by. TO USE THIS MICROSCOPE.