CHRONOMETERS

Evening Post, Volume CVII, Issue 82, 5 April 1924, Page 22

CHRONOMETERS

VALUABLE MARINE INSTRU

MENTS

INVENTION AND DEVELOPMENT,

An article in "The Geographical Journal ' for November, reviewing Lieut - Commander . Rupert T. Gould's "The Marine Chronometer," tells the interesting, story and .development of that indispensable aid' to navigation." The great problem-of rinding the longitude at sea; was constantly debated "in the ingenious company of the philosophers who formed trie .Royal Society, and ol the iierry Monarch who founded the itoyal Observatory. , The versatile HooKe turned his attention to the improvement of portable timekeepers in lfoy, and invented the balance spring, whose principle he concealed at first in a Latin anagram, according:to the custom of tha age; but a simple anagram not hard to resolve into the.proposition "Uttensio, sic vis1 -Sir. Cnnstoplier.Wren imagined three instruments- for finding the longtitude, but concealed his ideas in the archives-of the. Jioyal: Society in an anagram .which lias>ever been deciphered! Huyghens, on the other hand, with the assistance orf . the second Earl of Kincardine, actually constructed a liumber of timekeepers for use at sea which for a while were well thought of and sometimes gave moderate'satisfaction in use; .but as they were controlled by neudulums and had no 'temperature, compensation, they naturally-Tailed to pleaso tor very long, 'and Huyghens in 1774 proposed to replace the pendulum by the balance spring,, to the-great indignation of Hooke. ':.-•-■ '

The next great name is that of Leibnitz, -who "illustrated'his fatal propensity for writing upon subjects whose principles he had imperfectly mastered" ;■ but for a good number of years no real progress was made, and the need ■ became so urgent tliat: in 1714 the-cele-brated act of Queen Anne was passed, offering a reward graduated up to £&0 - OCO for any method capable of . determining the longitude within specified limits on a voyage from the British Isles to the West Indies. The decision was entrusted to commissioners, who became known .as the board .of langitude.. -They had to wait.long for a' practical method ' but meanwhile they "became the immediate and accessible prey of every crank, enthusiast, fanatic, swindler, and luna,tic in or out of Bedlam." .Our author's brief history.of the board makes, capital reading. .. • The most .remarkable thing in the Ion" history is that between, 1714, when the reward was offered, and 1765,; when the first half of;it was paid; there was only one serious comeptitqr for it, John Harrison; who was brought up as a carpenter, and never recieved any proper training as a clockmaker.' ■ ' '

lhe story.-of/John Harrison's struggles to perfect his ' machine the dramatic success of"the 'trials at'sea, the reluctance of the hoard to hand over the principal sum—though-they had been generous enough in advances on account —and the KingV effective-intervention on Harrison's behalf, are told with o-reat skill and ■ sympathy; thoroughly documented, and scrupulously fair to the aggrieved inventor and the cautious board. .Lhe famous chronometer-that >on the prize, "Harrison's Fourth'," v:wa!s never allowed to leave the country'" alter its trial voyages to Jamaica'and Barbados but the copies -made-by Kendall,to",the order of the hoard were- sbon r put-.ihto' service and proved .their worth. ,"■ The first was sent to sea with Cook in H.il.S, Resolution, and its excellent performance is often referred to in hisVjour.nal. The first and the third went on1 Cetjk s" third voyase in the discovery,. and were afterwards used- by-Vancouver and Flinders. The second. "was-lent ■to Captain Phipps, for his. Arctic voyage ■ and afterwards to Captain Blijrh of the Bounty, was carried off -by the mutineers, sold to an American whaler, stolen and sold to a Spanish. muleteer, 'and after other adventures bought by a' British 'naval captain.in Valparaiso.'. -Nevertheless, -and despite the'success of a few copies, -Harrison's, mechanism was almost .immediately superseded, by something much simpler, and stronger, and less expensive, .in the way first shown by Le Roy.. .In. 1766, after several earlier attempts, he presented to King Louis XV..- the..remarkable ■ "Mpntre. marine," which Commander' Gould calls "the first modern .chronometer."

"If we contrast/this .marvellous machine with -N0.!,4.-'which in its own way is equally wonderful, -Le Roy's superior-

ity as a. horolowist is evident.. Harrison took the escapement, balance, and genera! .arrangement of the ordinary watch of his day, and by fitting :i remontoire and maintainer, an automatic regulator, and diamond pallets, aided by high-num-bered wheels and pinions, and lavish jewelling, he' compelled it. to become an efficient-timekeeper. Le Boy attacked :the - problem from .'an' entirely different standpoint, and obtained 'his * result not by nullifying defects, but by eliminating them. The difference in their machines is fundamental—Harrison built a wonderful, house on the sand; but Le Roy dug .down to the rock." ' :,

, But Le Roy, having received the.prize of the Academy of Sciences, rested onhis oars, and his rival Berthoud it was who competed with the English makers, Arnold andEarnshaw,' for thecredit of making the marine chronometer a commercial success indispensable to every ship_. Commander .Gould discusses and elucidates, but cannot decide the question, ' which of the ' three originated the spring-detent, escapement that from about 1780 has survived nearly unchanged to the present day. From 1760 to 1780 was a remarkable period. At its beginning the reward of £20,000 was unclaimed. Before it ended the chronometer had . become almost standardised, and comparatively little of the first importance has been done to it since. The general principles of care arid stowage of chronometers are well-known; the hands should, be set forwards (never'back) by applying the key to the, square oii'the collet; there should bo no shake in the gimbals; they must never be twisted in parrying. But there are many smaller points in winding, starting, wedging the balance for transport, etc., which are less known, but of more importance.