Cover the box with gauze, over which place a piece of transparent glass, which is to be well fastened in. Let there be two grooves at each of the places C D E F, to receive two printed scenes, as follow: On two pieces of pasteboard, let there be skillfully painted, on both sides, any subject you think proper, as woods, bowers, gardens, houses, &c.; and on two other boards, the same subject on one side only, and cut out all the white parts: observe also, that there ought to be in one of them some object relative to the subject, placed at A, that the mirror placed at B may not reflect the hole on the opposite side.
The boards painted on both sides are to slide in the grooves C D E F, and those painted on one side are to be placed against the opposite mirrors A and B; then cover the box with its transparent top. This box should be placed in a strong light, to have a good effect.
When it is viewed through the sight hole, it will present an unlimited prospect of rural scenery, gradually losing itself in obscurity; and be found well worth the pains bestowed on its construction.
EASY AND CURIOUS METHODS OF FORETELLING RAINY OR FINE WEATHER.
If a line be made of good whipcord, that is well dried, and a plummet affixed to the end of it, and then hung against a wainscot, and a line drawn under it, exactly where the plummet reaches, in very moderate weather it will be found to rise above it before rain, and to sink below when the weather is likely to become fair. But the best instrument of all, is a good pair of scales, in one of which let there be a brass weight of a pound, and in the other a pound of salt, or of saltpeter, well dried; a stand being placed under the scale so as to hinder it falling to low. When it is inclined to rain, the salt will swell, and sink the scale: when the weather is growing fair, the brass weight will regain its ascendancy.
Another very simple method is, to take a strip of pine wood, about twenty inches long, one wide, and a quarter thick, and cut across the grain. Then take a strip of cedar, of the same dimensions, but cut along the grain. Glue them firmly face to face, and set them upright in a stand. Some time before rain falls, the pores of the pine will absorb moisture from the atmosphere, and swell until the whole forms a bow, which will straighten itself as fine weather approaches. It is needless to say that the rods should not be painted or varnished.
THE MAGICAL MEASURE.
The line to be measured must not be extravagantly long, otherwise it will be difficult to measure it accurately; for the least failure of a just aim, or departure from an upright position, would make very sensible errors in the measure of a very long line, especially if the ground was very uneven. To measure then the line A B, accessible at the extremity A, suppose the breadth of a small river, he who pretends to measure must stand very straight at the extremity A, and support his chin with a little stick resting upon one of the buttons of his coat, so as to keep his head steady in one position. He must pull his hat down upon his forehead till the brim of his hat covers from his view the inaccessible extremity B of the line to be measured A B, then he must turn himself to a level, uniform piece of ground, and with the same position of his hat, observe the point of the ground where his view terminates, as C, then measuring with a line or chain the distance A C, he has the length of the line proposed A B.
