Note 45 — J. E. MARR, M.A., F.R.S. (continued 2)
Reading edition
The lines 1, 2, 3 ... are incorrectly drawn in the figure. Line 1 should be drawn so as to separate a, b, c, d from a1, b1, c1, d1, line 2 to separate a1, b1, c1, d1 from a2, b2, c2, d2, and so with the others.