Читать книгу Essays on the Microscope - George Comp Adams - Страница 42

[34] Description and Use of an Opake Solar Microscope. 8vo. 1774.

Plate V. Fig. 1, represents the solar opake microscope, placed together for exhibiting opake objects.

Fig. 2, is that part called the single tooth and pinion microscope, which is used for shewing transparent objects; the cylindrical tube, Y, thereof, being made to fit into the tube E F, Fig. 1. It may be occasionally used as a hand single, or Wilson’s microscope, and for which purpose, the handle, c, is fitted by a screw to the body at g, and the tube, Y, screwed away.

Fig. 3, the slider which contains the six magnifiers; it fits into a dove-tail under P, Fig. 2, at the upper part of the microscope.

Fig. 4 represents a brass dove-tail slider, containing a small lens: it is called a condenser. There are three in number, marked 1 and 2, &c. corresponding to the number of the magnifiers used: they serve to condense the sun’s rays strongly upon the object, and enlarge the circle of light. They slide in at h, Fig. 2.

A B C D E F, Fig. 1, represents the body of the solar microscope; one part thereof, A B C D, is conical, the other, C D E F, is cylindrical. The cylindrical part receives the tube, G, of the opake object box, or the tube, Y, of the single microscope, Fig. 2. At the large end, A B, of the conical part there is a convex lens to receive the rays from the mirror, and refract them convergingly into the box, H I K L.

N O P is a brass frame which is fixed to the moveable circular plate, a b c; in this frame there is a plane mirror, to reflect the solar rays through the afore-mentioned lens. This mirror may be moved into the proper positions for reflecting the solar rays, by means of rack-work turned by the nuts Q and R. By the nut Q, it may be moved from right to left; it maybe elevated or depressed by the nut, R. d e, two screws to fasten the microscope to a window-shutter, or a board fitted entirely before the window.

The box for opake objects is represented as open at H I K L; it contains a plane mirror, M, for reflecting the light that it receives from the large lens to the object, and thereby illuminating it; S is a screw to adjust this mirror to its proper angle for reflecting the light. V X, two tubes of brass, one sliding within the other, the exterior one in the box, H I K L; these carry two magnifying lenses: the interior tube is sometimes taken out, and the exterior one is then used by itself. Part of this tube may be seen in the plate as within the box, H I K L.

At H, is a brass plate, the back part of which is fixed to a tube, h, containing a spiral wire, which keeps the plate always bearing against the side, H, of the brass box H I K L. The sliders, with the opake objects, Fig. 5, pass between this plate and the side of the box; to apply which, the plate is to be drawn back by means of the nut, g. k i, a door to one side of the opake box, to be opened when adjusting the mirror, M.

The foregoing pieces constitute the several parts necessary for viewing opake objects. We shall now proceed to describe the single microscope, which is used for transparent objects; but, in order to examine these, the box, H I K L, must be first removed, and in its place we must insert the tube, Y, of the single microscope, Fig. 2, now to be explained.

Fig. 2 represents a large tooth and pinion microscope; at m, within the body of this microscope, are two thin plates that are to be separated, in order to let the ivory sliders, Fig. 7, pass between them; they are pressed together by a spiral spring, which bears up the under plate, and forces it against the upper one. The slider, Fig. 3, that contains the magnifiers, fits into a hole at n; any of the magnifiers may be placed before the object, by moving the aforesaid slider: when the magnifier is at the center of the hole P, a small spring falls into one of the notches which is on the side of the slider, Fig. 3. At h, slides a condenser, Fig. 4, for condensing the sun’s rays, and enlarging the field of view on the screen: the number must correspond with that of the magnifier used. This microscope is adjusted to the focus, while exhibiting the object, by turning the milled nut O.