Chromatropes can be made in the same way, except that the small wheel has two grooves in its edge, and the other part is made up of two revolving frames, which are turned in opposite directions by one cord passing round both and the small wheel. The lower frame rests on the square glass, and the other frame rests on the lower one. The cord is passed from the right-hand side of the lower groove in the small wheel up the right side of the lower frame, round the top and down the left side to the left side of the upper groove in small wheel, round the upper groove to right side up to the left side of upper frame, round the top down the right side of frame to left side of lower groove of small wheel, brought round, and the two ends joined. It will be seen that by putting the cord this way the two frames are turned in opposite directions, although the small wheel turns them both. Have the cord tight, and well rub all the parts that work together with blacklead.
In painting chromatropes, each glass is painted with the same pattern, and then they are placed face to face, and in turning make very elaborate and constantly-changing figures.
V. Screen Frame for the Magic-Lantern.
By Frank Chasemore.
Great inconvenience is often caused in fixing a screen in a room for the lantern, such as taking down pictures, etc.; and sometimes it is impossible to hang it without doing some damage to the walls and paint by driving nails and hooks. Even then the screen has to be put up in an inconvenient place.
By using the following contrivance all this will be avoided. The screen can be put in any part of a room most suitable for the show, and afterwards taken to pieces in a few minutes and packed away in a box thirty-six inches long and about eight inches deep and wide.
The frame, or stand, can be bought at the shops, but it is much cheaper to make your own.
The materials for this frame can be bought at a small outlay, and are—fifteen wooden rods three feet six inches long and about an inch and a quarter in diameter—the handles sold at the shops for fitting to hair broom-heads do very well indeed, and are not very dear; two pieces of wood six inches long, five inches wide, and one inch and a quarter thick; and, lastly, some stout tin plate.
Fig. 1.
