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A BOY’S SOLAR MICROSCOPE.
The microscope is, as every boy knows, an optical instrument, which enables us to see and examine objects which are too small to be seen by the naked eye. The arrangement of the solar microscope is similar to that of the magic lantern, the sun taking the place of the limelight usually employed. In this form of the magic lantern, two difficulties are to be overcome; one, the necessarily fixed position of the instrument; and the other, the very inconvenient habit the sun has of constantly changing his position; so that it would be impossible to adjust the lens without the aid of a mirror, to throw sufficient light in upon the object to be examined. Both of these obstacles are surmounted in the simple arrangement of the solar microscope here described.
First make a strong frame of wood, seven-eighths of an inch in thickness, that will exactly fit in the lower half of the window when the sash is thrown up; and in the middle of this fit an upright board a foot wide, which has a hole cut in its center ten inches in diameter. Fasten it strongly in place by four nails driven through the frame, and well into the ends of the boards, or, if more convenient, by long screws inserted in the same places. Fig. 1 shows the position of the board a, also that of the nails b. The open spaces, c, are to be closed by several thicknesses of brown paper pasted or tacked across on the inside of the frame. The upper part of the window must also be closed, so that no ray of light shall enter the room, except through the hole d.
Before proceeding further, it may be well to remark, that, as perhaps the largest part of the work is the cutting of no less than seven circular holes of various sizes, through as many pieces of board, a scroll-saw will be found an almost indispensable aid to the construction of this apparatus. Also, that the window in which this microscope is used must necessarily have a southern exposure.
In Fig. 2 we have a disk of half-inch wood, twelve inches in diameter, with an opening in the center four inches across, to hold the condensing lens, a; b is a mirror five inches wide and ten inches long, turning on an axis which passes through the supports, c c, the latter being attached to the disk. These supports should be long enough to admit of the mirror turning entirely around without touching the disk, and are fastened in place by screws passing through the disk and into their ends. When the mirror is in place, cut the slit d parallel with the edge of the mirror, for the wire e to pass through. The manner of attaching the wire to the back of the mirror is seen in Fig. 3. The back is first covered with paper to prevent its scratching; then the wire is bent and laid in place, and lastly, a piece of very strong paper is pasted over the wire and entire back, and caught down over the edge of the front, forming a narrow frame to the glass; the ends of this wire should pass through rather small holes in c c, so that it will not turn easily out of position. A handle (see f, Fig. 4) should be placed on the other side of the disk, and just across the lens from the slit d.
