Читать книгу Essays on the Microscope - George Comp Adams - Страница 55

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This small instrument consists of three brass parallel plates, A, B, C; two wires, D and E, are rivetted into the upper and lower plate; the middle plate or stage is moveable on the aforesaid wires, by two little sockets which are fixed to it. The two upper plates each contain a magnifying lens, but of different powers; one of these confines and keeps in their places the fine point F, the forceps G, and the small knife H.

To use this instrument, unscrew the upper lens, and take out the point, the knife, and the forceps; then screw the lens on again, place the object on the stage, and then move it up or down till you have gained a distinct view of the object, as one lens is made of a shorter focus than the other; and spare lenses of a still deeper focus are sometimes added. The principal merit of this microscope is its simplicity.