No. LXVIII.—NUTS TO CRACK
A sharply-pointed knife with a heavy handle is stuck very lightly into the lintel of a door, and the nut that is to be cracked is placed under it, so that when the knife is released by a touch the nut is cracked.
What simple and certain plan can you suggest for making sure that the knife shall hit the nut exactly in the middle without fail?
67
A SINGULAR ENIGMA
Strange paradox! though my two halves are gone,
I still remain an undivided whole.
But were I double what I am, though one,
I then should be but half, upon my soul!
No. LXIX.—THE FLOATING CORKS
If we throw an ordinary wine cork into a tub of water it will naturally float on its side. It is, however, possible to arrange a group of seven such corks, without fastening them in any way, so that they will float in upright positions.