a Flemish Image of Mathematics in the Sixteenth Century
The use of the geometrical quadrant.
From Adriaan Metius, ArithmeticŠ libri duo: et geometriŠ libri VI (Leiden, 1640).
The linear division of the sides of the square means that the angles required are taken as ratios instead of in degrees; this allows the convenient conversion of, for example, lengths measured on the ground to inaccessible heights.
List of figures
(c) Museum of the History of Science, Broad Street, Oxford, England.