A SUM CLOCK

Hokitika Guardian, 26 January 1926, Page 3

A SUM CLOCK

SYDNEY INVENTION. SYiL-.KY. Jan. 5. In I a. esc days pm loci oil mm on-ci-s, It hCCIIIS like i;J ilie savage 1 .1 spc.tK 1.1 ami praise ;• new time-ca.'coia.m- teat requires co-operation ol t:.e ,1 l ITuU'.-s.u .w •L- Ccoue. o 1 tile Syit::e',' v;. \a - lory, lias; just imiipieiei!, oner many years ot research, o sun ice.; Gi.n won scientific acclaim all o. er i~e world. 4 iie eli.eK places in ; :u . h.nuis ill till' layman a method m e.:,coi.-!l in • time which is .simpler ami more :e m:rate than L l ll * siinilial, and e. niirniiv in use in England. America, imti.i, i.nil other conn tries. I*or thousands of years, ivh.m hours, minutes, anil seconds were yc-t unformed conceptions, man told t!:e mi.r uy the rising and felling ol the sun. I hen. wlicn lie began 1.1 glimpse the system oi the universe anil to oinlrrstand tlie movements of the planets and stars, lie divided the year anil Lite days and counted them off in the terms of burning 1 audios and running sands. One day a sanilia! was made, and the layman was given a method of measluing lime, more or less seieiifilie anil

correct., lull hopelessly unwieldy. During hundreds of years the sundial was flic hist word on ih:> subject lor the scicntiilic man, lor clocks suli’ered the disability <o all machinery they stopped often—and u-c cl the complex transit circle was within the powers nl only a few highly-trained ote-ei'vrr.s. In fact. It was the last word until a comparatively ice. moutlis a,-, when Professor Cooke found an easier and more accuiaft wav in Li; sm Hook. The problem of how ha might malic sundials less wield v and l educe tile thickness of their shadow has occupied Professor Cooke for many years an i always he has worked towards a type in which the complicate! mathematic::! calculations demanded by the ordinary sundial would no needless. FAt ITS OF SEND! AL. Thy: sundial has a fixed gnomon, v.hicli casts a shadow on a fixed dial, thus indicating solar time. This time, • it' course, is of little use to any me.

and t:i reduce it to the time in use a mathematical problem must, he solved. The precise position of ti e edge of the shadow must first, bo observed, but this cannot, accurately be defined to a minute or two. Than to obtain mean solar time one must refer to a table of equations, a"d add or subtract whatever number of minutes is appropriate to tlie date.

The sun clock which Professor O'oke has achieved after long aiul [willfully complex research, calls far no more difficult manipulation than the movement of a pivoted brass ring, which replaces the gnomon of the sundial. The axis of this ring is in exactly the same plane as .the gnomon would he if there was one—that is, its pivots lie along a line which points true north aw! the angle of its tilt is equal to the co-latitude of the place at which it is fixed. On the ring is a small hole, and on the inner surface of the ring, diametrically opposite the hole, is a graph. in the form of the figure S. to show the equation of time or the difference between apparent and mean, time for every day of the year. To find the time, one turns the ring towards the sun until the needle uf" sunlight which passes through the hale falls upon the line of the figure 8. Tim ring is geared to the hands of the clock, am! in turning the ring, one r.nconseiouslv sots 11 111 mean time of whatever conn try he is in. Y’ ' slcid-t----tions are required, for -{season'd variations of solar time and the difference due to tho longitude of the place in which the clock is ser up are compensated in the instrument, which, gives time correct to half a minute or less. The clock will do so many things besides telling the time—von can find true north and the day of the month with, it—that the inventor modestly describes it as “a delightful little astronomical plaything in addition.”