Ball, W. W. Rouse (Walter William Rouse), 1850-1925 · London, Macmillan · leaf 170
t column of the square: the lines in pencil B must be numbered similarly to correspond to the numbers in the second column of the square, and soon. To prevent confusion in the figure I have not inserted the numbers, but it will be seen that the method of construction ensures that the sum of the 8… … Age ) Ni wn ay 4 (7 4 VY Figure xv. A Magie Pencil, n=8.,
