The center piece can only slide up and down. Pieces cannot fall out through the transparent top plate. More assignments on the back of the puzzle. Material MDF.
The nummers are covered with transparent foil. You can slide without damage.
Old puzzle. Copy produced by puzzle design Ton Delsing.9 cardboard pieces. The puzzle was patented in 1911, This variation on Thurston's puzzle was used as an advertisement for soap. The idea was to arrange the cards so that each center circle contained four different colors and each half circle contained two.
Put the 15 numbers in order. Pieces can't fall out because of transparent top plate,More assignments on the back of the puzzle. Material MDF.The numbers are covered with transparent foil. You can slide without damage.The letters are covered with transparent foil. You can slide without damage.
Everyone knows the problem of 8 queens on a chessboard, In the puzzle is a booklet with all the assignments. But I also came up with my own assignments. Material plastic.1. Make lines with 2 DOTS. Horizontal, vertical or diagonal. I found 32 lines 2. Do this also for 3 DOTS. 13 lines found. 3. Do this also for 4 DOTS. 8 lines found.