To investigate the properties of lenses and to construct simple optical instruments. Kit comprised of the following: Two lamp holders, each in cast alloy shade with two axial slots. Complete with two meter 2-core cable and lamp. Shade has integral support arm which is clamped at right angle to the vertical rod, 165 mm long, fitted on heavy cast base, stove hammer finish. One each right and left hand cylindrical lamp shield of light alloy in matt black finish with slot parallel to the axis, size 190 x 60 mm, Height x Diameter. Two black plastic plates, 100 x 80 mm, with 17 equispaced parallel slots. Two black plastic plates, 130 x 80 mm, each with single and triple slits. Two metal support brackets, matt black finish with spring-loaded clips to hold the plates. Four black finish metal light barriers, height 80 mm. Ten Cylindrical Lens ( 8 plano-convex, and 2 plano-concave ), size 50 x 50 mm, Side x Height. Manual included.