A scarce work on navigation, astronomy and the salvaging of ships. The three parts each have separate pagination. The author writes of attempts made to salvage the Spanish galleon sunk off the the Isle of Mull in 1588, points out that the weight of the vessel is identical with the displacement, and suggests that air containers, called 'Arks', open at the bottom, should be secured to the submerged wreck and air admitted, either by pumping through leather pipes, or by divers introducing it with the aid of inverted buckets or inflated skins. He also refers to the use of a diving bell.

George Sinclair (died c 1696) was Professor of Mathematics at the University of Glasgow from 1691 until 1696 and gifted money to the fund for the building of the Old College. The George Sinclair Chair in Mathematics was founded in 1984.

Sinclair may have been born in the Haddington area and was Professor of Philosophy at the University of St Andrews before moving to Glasgow in 1655. He resigned in 1667 when University professors were required to submit to the Episcopal form of church government. He became a mineral surveyor and engineer, and then a schoolteacher in Edinburgh where he was also employed to supervise a project to bring fresh drinking water into the city. He published several important books on mathematics and practical physics.

In 1688, Sinclair returned to the Glasgow University having declared his readiness to swear the oath of allegiance to King William III. He was Professor of Mathematics and Experimental Philosophy from 1691 until his death.