Can you, keeping always on the straight lines, cut this into four pieces, and arrange these as two perfect squares, in which every semicircle still occupies the upper half of its cell?
A HOME-MADE MICROSCOPE
The following very simple recipe for a home-made microscope has been suggested by a Fellow of the Royal Microscopical Society:—
Take a piece of black card, make a small pinhole in it, put it close to the eye, and look at some small object closely, such as the type of a newspaper. A very decided magnifying power will be shown thus.
No. CVII.—IN A TANGLE
Where on this diagram must we place twenty-one pins or dots so that they fall into symmetrical design and form thirty rows, with three in each row?
