THE RIGHT TIME

Evening Star, Issue 18832, 5 January 1925, Page 2

THE RIGHT TIME

GREENWICH AT WORK. For ihe reason (Eat it is governed by nih-s forbidding admittance to any but ostmuoniers and privileged visitors, Greenwich Observatory, which may soon be moved into more suitable surroundings, is at cure the most famous and the least known institution of its kind in the world. Greenwich Observatory is a monument to one of tho few really wise actions Charles If. Founded by him in 1675 for “ the promotion of Astronomy and navigation,” it was not until many years bad elapsed that tho public as a whole appreciated its usefulness. A good illustration of the ignorance that prevailed was shown by tho fact Lhot when, at the time of Queen Victoria’s accession, Sir George Airy was appointed Astronomer Royal "or Astronomical Ohservator, as the holder of the position was formerly known, he was inundated by letters addressed to “The Astrologer Royal,” the writers of which begged him to east horoscopes, tel] their fortunes, and so on. CRANKS’ THEORIES. Incidentally, tho Astronomer Royal was also pestered by cranks who sought to impress him wit.li their theories of the earth’s Hal ness and other far-fetched ideas. This class of Liter wns put away in pigeon holes, with subdivisions for earth Halt oners,” “ earth-sqnarers,” and tho rest, the wliolo collection being labelled ‘■lnsanity!” Not everyone knows how Greenwich mean time is determined, although there, is a widely-held belief that tho sun is closely associated with tho calculations. Rut, the sun is by no means the safest of guides, being itself uncertain in its movements.' At one season it may be ten minutes slow, and at another time it maybo ahead ol correct time. A check is kept, in Greenwich in what is known as the Transit Room by menus of a, giant telescope which can bo ■focussed on'any part of the heavens when a. part icular star is due to cross tho Greenwich meridian, or to ho more precise, at exactly when tho part of the earth turning on its axis brings tho telescope in alignment with tho star. This chocking process goes on constantly, the result being sent out hourlyall over the country. Errors are corrected just before 10 a.m. and 1 p.m., but what mistakes there are seldom exceed iwqleulhs of a second—a remarkable testimony to the efficiency of tho staff and the instruments. Every day the Greenwich clock is adjusted to in ark accurate time, and it is this clock which now- ticks in the homo of every wireless listener. Before the minute 'of time to bo recorded the preceding five seconds nno heard as clicks; tho time signal itself, falling on the exact zero, is heard as a louder click than the others. These clicks are tho sound of the escape wheel, which is permitted to touch a spring with six successive teeth. This mokes an electrical contact, which transmits a current direct to the London broadcasting station’s aerial. The per, sonal factor is thereby entirely eliminated. CURIOUS TASK. One of the most curious tasks for which, the official astronomers are responsible consists of baking tho chronometers used in the Royal Navy. Eve 17 chronometer is tested at the Observatory, those required on extended cruises in varying climates being kept apart for two mouths in an oven heated to a temperature of 90deg. Inspection of tho Observatory registers, in which axe entries relating to the testing of chronometers over many yeans, sheds sidelights on more than one famous episode. On one page, for instance, you may see particulars of several chronometers bought in 1842 by the side of which appears the note, “Lost in the wreck of Birkenhead.” The chronometer issued to Sir John Franklin for his ill-fated trip to the Par North-west is recorded, with tho endorsement that it was lost on the journey.