** How to Make Silhouettes [68]

Photography in all branches is truly a most absorbing occupation.  Each of us who has a camera is constantly experimenting, and everyone of us is delighted when something new is suggested for such experiments.

[Illustration:  Making a Silhouette with the Camera]

To use a camera in making silhouettes select a window facing north if possible, or if used only at times when the sun is not on it, any window will do, says the Photographic Times.  Raise the window shade half way, remove any white curtains there may be, and in the center of the lower pane of glass paste by the four corners a sheet of tissue paper that is perfectly smooth and quite thick, as shown in the sketch at B. Darken the rest of the window, shutting out all light from above and the sides.  Place a chair so that after being seated the head of the subject will come before the center of the tissue paper, and as near to it as possible, and when looking straight before him his face will be in clear profile to the camera.

Draw the shades of all other windows in the room.  Focus the camera carefully, getting a sharp outline of the profile on the screen.  Do not stop down the lens, as this makes long exposure necessary, and the subject may move.  Correct exposure depends, of course, on the lens, light and the plate.  But remember that a black and white negative is wanted with as little detail in the features as possible.  The best plate to use is a very slow one, or what is called a process plate.

[Illustration:  Sample Silhouette]

In developing get all possible density in the high lights, without detail in the face, and without fog.  Printing is best done on contrasty development paper with developer not too strong.

The ideal silhouette print is a perfectly black profile on a white ground.  With a piece of black paper, any shape in stopping off print may be made as shown at C in the sketch.

** How to Make a Galvanoscope [68]

A galvanoscope for detecting small currents of electricity can be made from a coil of wire, A; a glass tube, B, full of water; a core, C; and a base, D, with binding posts as shown.  The core C, which is made of iron and cork, is a trifle lighter than the water it displaces and will therefore normally remain in the top of the tube; but as soon as a current of electricity passes through the coil, the core is drawn down out of sight.  The current required is very small, as the core is so nearly balanced that the least attraction will cause it to sink.

The glass tube may be a test tube, as shown in Fig. 2, or an empty developer tube.  If one has neither a test tube nor developer tube, an empty pill bottle may be used.  The washers at the ends of the coil can be made of fiber, hard rubber, or wood; or can be taken from an old magnet.  The base may be made of wood or any other insulating material and should have four short legs on the bottom.  Make the coil of single-covered wire about No. 18 and connect ends to binding posts as shown in Fig. 2.