In 1730 Godfrey invented an improved backstaff or Davis quadrant, and loaned the instrument to Joshua Fisher to be used in the latter's survey of Delaware Bay. It is claimed that the location of Cape Henlopen was established on Fisher's map (published in London in 1756) by means of Godfrey's instrument. James Logan became interested in the improved backstaff invented by Godfrey and at Logan's request, the instrument was taken on a voyage to the West Indies by a Captain Wright for the purpose of testing it.[61] At the same time Logan sent a description of the instrument to London to the Royal Astronomer, Edmund Halley. No acknowledgment was made, and in 1734 Logan sent a second description to Sir Hans Sloane and to Peter Collison for forwarding to the Royal Society. The arrival of this description coincided with the submission of the description of a similar instrument to the Society by its vice president, James Hadley. The Royal Society decided in favor of both inventors, and Godfrey was awarded the equivalent of 200 pounds in household furniture. [Illustration: Figure 29.--Brass surveying compass made by Isaac Chandlee (1760-1813) of Nottingham, Maryland. Photo courtesy Ohio State Museum.] Godfrey is often confused with his son, also named Thomas Godfrey (1736-1763), who worked as a watchmaker in Philadelphia, and subsequently became active in literary arts. Benjamin Condy (fl. 1756-1792, d. 1798) was an instrument maker with a shop on South Front Street in Philadelphia. As early as 1756 he worked for most of the merchant shippers of the port, supplying them with a considerable number of sand glasses that ranged from the quarter-minute to the two-hour varieties. Although he made his own mathematical instruments, it is likely that he imported the sand glasses. According to Customs House clearances of 1789, he had imported from London on the ship _Pigou_ "three cases of merchandise" valued at L160/17/6 with a duty of $32.19, which may have included sand glasses.[62] When Condy retired in 1792 he was succeeded in business by Thomas Biggs at the same address. Biggs had originally served an apprenticeship with Condy, and then fought for the American cause in the Revolution for five years. Following the termination of his military service he had engaged in instrument making in New York for eight years before returning to Philadelphia, his native city. Biggs prospered and his advertisements continued until early in 1795. Thomas Pryor made instruments in a shop on Chestnut Street in 1778, but he evidently retired from business in the 1790's because the city directory of 1795 listed him merely as "gentleman." He is reported to have been one of those who, from the State House Yard, witnessed the transit of Venus.[63]