Comprising a small wooden frame of size 5”x
3”x 3” with a matt blackened inside and provided with a glass plate 4” x 3” x
1/8 0 mm mounted at an angle of 45 to reflect the light downwards on to a
Plano-convex lens of 50 mm diameter having 100 cm focal length which rests on a
plain glass plate 3” x 3” x 3/8 on the base of the box.
