Various simple activities are being developed by the French Comité de Liaison Enseignants Astronomes (CLEA) in the training of school teachers. We give in the following one example of a very simple instrument which we call “Alphonse’s box,” after Alphonse Delavergne who invented it. It is also called a heliograph. This very simple and inexpensive instrument enables (1) the plotting of the daily apparent path of the sun, (2) the determination of the duration of sunlight, and (3) the determination of the declination of the sun. The following description is due to Maryse Jonas:
1. photosensitive paper (used by architects) that can be handled in semi-darkness; its sensitive face is yellow and it is developed by the vapor of an ordinary ammonia solution in about ten minutes;
2. a simple can, with a cover that will shut tight; approximate dimensions: diameter 10 cm, height 15 cm, with a hole about 0.5 mm in diameter on one side;
3. two pieces of wood, 15 x 15 cm and 15 x 20 cm; one butt hinge; one threaded rod with two nuts and two washers.