4. "Spencer Browning and Rust London." Ebony frame, brass arm 17 inches, ivory scale, pencil inserted in cross piece, _ca._ 1800, used by Capt. Henry King. 5. "J: Urings London." All brass, arm 20 inches, back sight broken off, _ca._ 1780, rare.] To obtain the ship's latitude with comparatively good results was an easy matter with the quadrant and its fore-runners, but the great problem for centuries was how to find the longitude, now universally and quickly obtained by the chronometer and simple observations in the morning or at noon. Spring clocks and watches appeared about 1530 but they were unreliable and of no use on long voyages. Sand glasses like those of the old Colonial churches were used on ships and so conservative is the British mind that some were in use on British naval vessels as late as 1828 and one authority states as late as 1839. Greenwich Observatory was established in 1675 and a Royal Commission was soon appointed with authority to award prizes for important inventions in aid of navigation. A prize of £20,000 was finally offered for a time-keeper that should meet certain requirements which practically meant absolute accuracy. In 1767, John Harrison produced the chronometer, based on the principle of an invention of 1735, and eventually he received the reward. Chronometers were so expensive and so hard to obtain that few New England ships had them until more than a half a century later. Other devices were tried to obtain longitude by lunar observations and by Jupiter's satellites, but these observations were too difficult to be of practical use. Today, fine watches serve for short trips and chronometers are carried by nearly all vessels making long voyages. That so important an instrument as a telescope or spy-glass is rarely mentioned in books on navigation or in sea journals seems strange. It is exceedingly difficult to obtain information of any being taken to sea, although one would think a spy-glass would be about the first aid on ship-board especially when skirting the coast. Telescopes did not become of practical use, even if the principle had been known, until they were made in Holland in 1608. It is at least certain that Columbus did not have one and probably there was none on the _Mayflower_, although its passengers had recently come from Holland where telescopes were invented a few years before. So far no references to them have been found in a rather casual examination of old log-books.