Astronomical mathematics, 19th-century diagrams. At lower left is an armillary trigonometer based on a design by British shipwright Mungo Murray (c.1705-1770). It tracks months and days, and the degrees of solar declinations. The magic square of squares (top, 16x16) contains the numbers 1 to 256. Rows, columns, and marked lines add up to 2056. The magic circle of circles (lower left) contains the numbers 12 to 75. The columns and circles add up to 348. Diagram from 'The Works of James Ferguson, F.R.S.' (1823) containing works by Scottish astronomer and instrument maker James Ferguson (1710-1776).