A brief description of a new instrument, invented by Mr. Caleb Smith, for taking altitudes of the sun, moon, and stars, from the visible horizon; or any other angles at sea: Whereby the interruption, and inconvenience, occasioned by the ship's motion, in observing with the quadrants commonly used, is remedied, and prevented. And the latitude found with great ease, accuracy, and expedition. With directions how to use it at Sea. Made and sold by George Adams, at Tycho Brahe's Head, near the Castle-Tavern in Fleetstreet, London; who makes, and sells, by wholesale and retale, and sorts of mathematical instruments, for land and sea, curiously and exactly finished in silver, brass, ivory, wood, &c. for the purposes of geometry, surveying, gauging, measuring, architecture, astronomy, geograghy, navigation, &c.