Magic circle of circles. Figure derived by Benjamin Franklin containing the numbers 12 to 75 inclusive on a set of concentric circular spaces across eight radii. The numbers are so arranged that the total within each concentric circle plus the 12 at the centre equals 360, the numbers on each radius plus the central 12 total 360, and any four numbers on adjoining radii (as if the corners of a square) plus half the central 12 total 180. There are also four sets each of five circular spaces set eccentrically - the numbers in any of these circular spaces plus the central 12 total 360. This figure was printed in the Gentleman's Magazine in 1768.