made smaller without loss of measurement accuracy. The rights for a portable sextant designed by Ramsden and used for maritime navigation were purchased by the Board of Longitude in 1777 for £300. An additional £315 was paid to allow for its construction details to be used by other craftsmen. He also received charges for servicing of the instruments. Ramsden was of a genial disposition, but at the same time infuriated his clients with his tardiness in delivering their purchases, particularly of larger commissions. His three-year delay in providing William Roy with the theodolite for the Anglo-French Survey (1784–1790) provoked a public row within the portals of the Royal Society and in its Philosophical Transactions. Many delays could be attributed to Ramsden's quest for perfection, as he continually refined his designs as the slightest shortcomings were revealed. Ramsden was elected to the Royal Society in 1786 and to the Royal Society of Edinburgh in (probably) 1798. The Copley Medal of the Royal Society was bestowed upon him in 1795 for his 'various inventions and improvements in philosophical instruments.’ Ramsden's health began to fail and he traveled to Brighton on the south coast to try to benefit from its better climate, but died there on 5 November 1800. He was buried at St James's Church, Piccadilly on 13 November. His instrument-making business in London was taken over by his foreman, Matthew Berge until his death in 1819. The estate passed on to his son. Many of Ramsden's apprentices such as William Cary went on to establish their own instrument-making ventures. Others like Edward Troughton incorporated ideas from Ramsden into their own designs. Ramsden's instruments Dividing engines Ramsden created one of the first high-quality dividing engines. This led to his speciality in dividing circles, which began to supersede the quadrants in observatories towards the end of the 18th century. He published a Description of an Engine for dividing Mathematical Instruments in 1777. Other instruments He also invented electrostatic generators. Surveying instruments In about 1785, Ramsden provided General William Roy a new large theodolite which was used for the measurement of the latitude and longitude separations of London (Greenwich) and Paris and later for the Principal Triangulation of Great Britain. This work provided the basis for the subsequent Ordnance Survey of the counties of Britain. Telescopes Ramsden is also responsible for the achromatic eyepiece named after him. In its simplest form it consists of