PRACTICAL ASTRONOMY

Dominion, Volume 12, Issue 142, 11 March 1919, Page 7

PRACTICAL ASTRONOMY

RADIO TIME SIGNALS WORK OF HECTOR' OBSERVATORY A report issued by the Government Astronomer for fho period June 20, 19.17, to August 31, 1918, deals with tho work done at tho Hector Observatory. It is largely technical in character. Tho report mentions that the daily tinio signal is sent from tho observatory standard clock to somo 2100 telegraphic stations by the Telegraphic Department every day, except Sundays, nt 9 a.m. Tho operation is an interesting ono. A clcck in tho telegraph, operating 1:00111 at Wellington is kept to. correct time by comparison with the time signal from tho observatory standard clock. At a. few minutes beforo 9 a.m'. nil ■ the telegraph offices are called to attention by. the Morso signal "LS," which is repeated until tho. supervisors call "Time," exactly at 9 a.m., when''each operator telegraphs tho word•- Time." 'By this means all tho railway and telegraph offices receive correct time''signals. The more accurate signals required' for rating chronometers are sent entirely, automatically from tho observatory clock, over the telegraph .lines. '..-.. The .astronomical clocks at. tho Hector Observatory have developed certain irre-. gulari'ties- in their, rates, and they have, beon overhauled and adjusted, but with-: out showing much improvement. "Ex-, periencc this year again confirms the previous conclusion that clocks of more, modern type in airtight cases are required for standard clocks," writes Mr. Mann; "Owing to tho irregularity in the rates of the standard docks it lias been necessary -. to' disconnect ■• tho gnlvauo- ■ meter in the public telegraph office, Wellington; and in a re&ent interval of had weather it becaino necessary to suspend all tinio signals until observations could be obtained to determine-the clock error. Proposals for the improvement of tho. time, service equipment are under consideration by the Government" "Nothing further-has .been- done, to complete tho' radio receiving outfit at tho observatory. With a view to cheeking, •tho observatory-clocks arrangements were made with Dr. J. M. Baldwin, Government Asiromoher, • Melbourne, to. send, scientific time- signals by radio twice a. week, from -the; Melbourne Observatory. 'Unfortunately, tho apparatus at our observatory is not sufficiently sensitive to hear these signals with. Such signals are invaluable during intervals of bad. weather, when observations cannot boobtained at our observatory. Suggestions for' suitable apparatus are now under consideration, and it is expected that the equipment'will bo put. in working order ore long. "Further experiments have been made in sending out time signals from the observatory, by radio-telegraphy. , The same .series of fivo signals (referred to above) during the".first five minutes of the hour is soivt'froni tho Awahui Radio Station. The Telegraph Department have provided' a direct connection between tho observatory signal clock -and a relay at Awanui over a land line.about GOO miles lc^ ; g. The relay operates a sounder which serves as a key to work tho high-power transmitting apparatus. ' The receiving apparatus' at the observatory is capable, of receiving the radio time signals sent out by Awanui, and they have • been checked'frequently. It is possible to hoar the click of the observatory signal clock with one enr, and with the radio re-, ceiver on the other ear tho radio signal from- Awanui is clearly heard. It is not possible to delect any difference between the two sounds, so.that for all practical purposes the signals may be considered to be simultaneous', No doubt there is •some slight' difference between the two sounds, and steps will be taken to measure the lag by mcsiig of the chronograph as soon as some reliable method of automatically recording the radio ■time signals is devised. ' "Tho radio, time signals sent from tho observatory have been received at Tahiti, Rarotonga, and other Pacific islands, while captains of steamers report that the tiiiie signals have-been'heard at Honolulu.'- As radio stations are now constructed:, at Chatham Islands, Rarotonga, Samoa, and other Pacific islands, it will be possible to determine the differences of longitude between the.?? places and ,the observatory. In this way the charts can be corrected. Similarly, the differences of longitude between the observatory and the other islands near New Zealand can be determined as soon as a vessel fitted with radio-telegraphic apparatus is available for this service."