Surveyor's folding rule, 1574.
© Science Museum / Science & Society Picture Library
Detail. A bras folding rule, signed and dated by Humfrey Cole (1530?-1591). Cole was the first craftsman of the English instrument-making trade, which became established in the 16th century. This instrument is a surveyor's compendium. When fitted with sights it can be used to measure and draw land surveys to scale. On the reverse it carries mathematical tables, a quadrant, and a sundial. They were probably bought by gentlemen and wealthy practitioners keen to demonstrate their mathematical skill.