PRACTICAL ASTRONOMY.

Hokitika Guardian, 18 March 1919, Page 4

PRACTICAL ASTRONOMY.

RADIO TIME SIGNALS

WORK OF HECTOR OBSERVA- : TORY. j A report issued by the Govern- ; ment Astronomer for the period June 20, 1917, to August 31, 1918, , J deals with the work done at Hector j Observatory. It is largely technical ! in character. j The report mentions that the daily j time signal is sent from theobservatory standard clock to some 2,400 telegraphic stations by the Telegraphic Department every day, except Sundays, at 9 a.m. The oper- j ation is an interesting one.' A clock i in the telegraph operating room at 1 Wellington is kept to correct time ! by comparison with the time signal t from the observatory standard clock. J At a few minutes before 9 a.m. all the telegraph offices are called to J attention by the Morse signal j “ L 5.,” which is repeated until the supervisors call “Time,” exactly at 9 a.m., when each operator telegraphs the word “ Time.” By this means all the railway and telegraph offices receive correct time signals. The more accurate signals required lor rating chronometers are sent entirely automatically from the observatory clock over the telegrajrh lines. The astronomical clocks at the Hector Observatory have developed certain irregularities in their rates, and they have been overhauled and adjusted, but without showing much improvement. “ Experience this year again confirms the pievious conclusion Goal clocks of more modern type in airtight cases are required for standard clocks,” writes Mr Mann. “Owing to the irregularity in the rates of the standard clocks it has been necessary to disconnect the galvanometer "in the public telegraph office, Wellington ; and in a recent interval of bad weather it became necessary to suspend all time signals until observations could be obtained to determine the clock error. Proposals for the improvement of the time service equipment are under consideration by the Government. “ Nothing further has been done to complete the radio receiving outfit at the observatory.' With a view to checking the observatory clocks arrangements were made with Dr J. M. Baldwin, Government Astromoner, Melbourne, to send scientific time signals by radio twice a week from the Melbourne Observatory. Unfortunately, the apparatus at our observatory is not sufficiently seusi tive to hear these signals with. Such signals are invaluable during intervals of bad weather, when observations cannot be obtained at our observatory. Suggestions for suitable apparatus are now under consideration, and it is expected that the equipment will be put in working order ere long. “Further experiments have been made in sending out time signals from the observatory radiotelegraphy. The same series of five signals (relerred to above) during the first live minutes of the hour is sent from the. Awanui Radio Station. The Telegraph Department have provided a direct connection between the observatory signal clock and a relay at Awanui over a laud line about 600 miles long. The relay operates a sounder which serves as a key to work the 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 hear the click of the observatory signal ; clock with one ear, and with the ) radio receiver on the other ear the radio signal from Awanui is clearly heard. It is not possible to detect 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 means of the chronograph as soon as some reliable method of automatically recording the radio lime signals is devised. “Hie radio time signals sent from the observatory have been received at Tahiti, Rarotonga, and other Pacific islands, while captains of steamers report that the time signals have been heard at Honolulu. As radio stations are now constructed at Chatham Islands, Rarotonga, Samoa, and other Pacific islands, ft will be possible to determine the differences of longtitude between these places and the observatory. In this way the charts can be corrected. Similarly, the differences of longtitude between the observatory and the other islands near New Zealand can be determined as soon as a vessel fitted with radio-telegrapliic apparatus is available for this service.”