Читать книгу Essays on the Microscope - George Comp Adams - Страница 40

Screw one of the five cells, which contains a magnifying lens, to the end, D, of the body; place the slider i or k, with the objects, between the plates of the slider-holder, K. Then, to attain distinct vision and a pleasing view of the object, adjust the sliding body to the focus of the lens you are using, by moving the upper part, C, gently up and down while you are looking at the object, and regulate the light by the concave mirror, I, below. The image of the objects in this microscope is seen in a field of view of about six inches in diameter; but, in the improved ones before described, it is from about twelve to fifteen inches.

For opake objects, two additional pieces must be used; the first is a cylindrical tube of brass, represented at N, which fits on the cylindrical snout above D of the body: the second piece is the concave speculum, L; this is to be screwed to the lower end of the aforesaid tube. The upper edge of this tube should be made to coincide with the line which has the same number affixed to it as the magnifier you are using; that is, if you are making use of the magnifier marked 5, slide the tube to the circular line on the tube above D, that is marked also with No. 5.

The slider-holder, K, should be removed when you are going to view opake objects, and a plane glass should be placed on the stage in its stead to receive the object; or it may be placed on the nippers, b, the pin of which fits into the hole in the stage.