It will be observed that this apparatus obviates two difficulties: 1, that of the exactness of the sketch, in copying nature as it is presented to the eye; 2, that of perspective. Having the sketch on glass it is easy to transfer it on paper. Lift up the rule, E E’, so as not to be in the way, place oiled or transparent paper on the glass, and counter-draw the sketch on it. You can then stick this paper on a cardboard, and, if the operator is a designer, he may reproduce in crayon a very fine drawing. For the shading he must use his own talent, the aim of the instrument not being to give a finished drawing, but only a sketch, vigorously exact, and in unexceptionable perspective. This instrument is often very convenient. When wishing to have a true sketch, you trace it on the glass; you then transfer it to an oil-paper, and again on drawing paper if the former is not to be used. Besides, if one has an exact sketch on whatever paper, you may reproduce it in freehand, if you are blessed with any idea of drawing. If the varnished plane has to serve again, wash it with warm water, and let it get dry; then the varnishing can be done over again. Camphor in Water. If you put very small pieces of camphor on the water, you will see them turn round each other with great velocity. These movements are due to the diminution of the superficial tension of the liquid in the vicinity of the pieces of camphor. In order to stop them throw a drop of oil in the water, and you will produce a perfect calm. One may utilize the camphor for an amusing recreation. Construct a small paper or cardboard boat and fasten underneath on the hind part or stern a piece of camphor. Your boat will maneuver on the water. Persons not initiated will be much puzzled, and be long to find out by what contrivance this small craft is propelled. A Simple Multiplier. Write on a card or strong paper the letters, figures, etc., which you want to reproduce. Then all along the lines or tracing, with a needle, prick holes in close proximity at equal distances. Place the sheet so prepared on a pad made of several sheets of blotting paper, smeared with blue analine ink, or a mixture of lamp-black and oil. Fix the corners with tacks or drawing pins, and draw your copies by simply placing the blank sheets over the pricked one, and press them down. The words, figures or designs will be reproduced in dotted lines if the holes have been well pricked. In this way a good number of copies can be drawn. The Drawing Room Mirror. On one of the faces of a pane of glass smear some lamp-black mixed with oil. If you place this glass, thus prepared, vertically on an engraving representing flowers, fruits, birds, etc., you will obtain an infinity of forms, some of which will be very striking. [Illustration]