Briefly, the history of this problem is as follows. Longitude is, of course, the distance which a ship makes east or west. These eighteenth-century navigators had their quadrant for finding their latitude, and they used the log-line, log-ship, reel, and half-minute glass to tell them roughly and inaccurately the distance sailed by the ship. These, by the way, were kept stowed in the “bittacle” (binnacle), which in those days was a wooden box arrangement containing a compass on each side with lights in between. There were usually two of these “bittacles” on board, viz. one for the steersman and one for the “person who superintends and directs the steerage,” says Moore, “whose office is called conning.” The accompanying illustration will indicate quite clearly the appearance of an eighteenth-century “bittacle.” Throughout history all sorts of efforts had been made to do for longitude what the quadrant and cross-staff had done for latitude. The great voyages of discovery in the early sixteenth century had especially given this research an impetus. In 1530 and again in 1598 a means had been sought. Philip III of Spain offered a thousand crowns to him who should discover the instrument for finding longitude. All sorts of prizes were offered by different Governments at different dates. The States of Holland held out an offer of 10,000 florins. The melancholy wreck of Sir Cloudesley Shovel on the Scillies with his squadron caused the English Parliament, in 1714, to offer £20,000 for any method which could determine the longitude. Two years later the French Government offered 100,000 livres, and so the impetus continued without avail. The whole civilised world was crying out for something which no scientist could give. And then, in 1765, the English prize was at last won by John and William Harrison, who were able to make instruments most suitable for this purpose, and received the £20,000. This was that invaluable little article the chronometer, which means so much to the modern mammoth steamships. Dr. Maskelyne, the Astronomer Royal, had, in 1754, discovered the method of finding longitude by lunar observations on shore. After navigators at last began to employ chronometers the dawn of modern methods had already occurred. In 1767 came the first publication of the “Nautical Almanac,” Hadley’s quadrant was made known in 1731, and the sextant in 1761. Perhaps, as the sailing masters in the Navy had to provide their own nautical instruments, there was not such an incentive to accustom themselves to new methods as might otherwise have been the case. [Illustration: INTERIOR OF AN EIGHTEENTH-CENTURY THREE-DECKER.] [Illustration: INTERIOR OF AN EIGHTEENTH-CENTURY MAN-OF-WAR. Showing decks, cabins, holds, etc.]