The term "compass" or "compasses" denotes a wide range (fig.1) of instruments for drawing, measurement, and proportional calculation. Besides the more common compasses for drawing circumferences, widespread since antiquity (fig.2), the Renaissance has left us a great number of special compasses, whose names reflect their specific functions: oval compasses to draw ellipses , hyperbolas and parabolas (fig.3); two-point compasses (fig.4) —also called dividers—to divide lines and transfer measurements; nautical compasses (fig.5), to track routes on sea-charts; compasses with curved points, called gunner's compasses (fig.6), to measure mouths of cannons, cannon balls, and columns; three-legged compasses (fig.7) to reproduce maps; four-point compasses (fig.8), or reduction compasses, to enlarge or reduce drawings, divide lines and circumferences proportionally, and draw polygons; eight-point compasses (fig.9) to measure fractions of degrees and carry out proportional calculations; proportional compasses (fig.10) to perform arithmetic, geometric, and trigonometric calculations and to measure weights, gradients, and distances for military use; and sophisticated surveying compasses (fig.11) that combined a magnetic compass, a windrose, and optical sights for surveying and for drawing topographic maps.