West Australian (Perth, WA : 1879 - 1954), Thursday 18 October 1923, page 9


PERTH OBSERVATORY.

A Question of Longitude.

Early in the year Mr. H. B. Curlewis (the Government Astronomer) issued preliminary figures for the longitude of the Observatory. Now, after consider-

able correspondence with the Govern-ment Astronomer of Sooth Australia, who co-operated with him in the deter-mination of the longitudes of two places on the State's eastern boundary, Mr. Curlewis is able to make available the final figures for Perth, and for these two places on the boundary. Last night he made the following state ment: — "The interval between the tak-ing of the necessary observations at the various points and the appearance of the final results may seem long, but when it is remembered that both observatories are understaffed and that all the points requiring discussion, which crop up in a work of this kind, have had to be elucidated by letter, the reason for the delay can be understood. The results are as follow: — The longitude of the Perth Observatory by wireless signals (depending upon 120 separate compari-sons) works out at 7 hours 43 minutes 21.46 seconds east of Greenwich. The longitude by cable and land-line was 7 hours 43 minutes 21.74 seconds — the mean of figures obtained in 1899, 1901, and 1911. Greater weight has been given to the wireless determination, since it is direct from Greenwich, and the number of separate comparisons were Far greater, with the result that the final longitude of the Perth Observatory has been fixed as 7 hours 43 minutes 21.50 seconds east of Greenwich, or in arc 115deg. 50 minutes 22.50 seconds. The final longitude of the observatory pillar it Deakin, on the trans-Australian rail-way, depending upon 170 comparisons, has been fixed at 8 hours 35 minutes 52.61 seconds east of Greenwich, or in arc 128deg. 58 minutes 9.15 seconds, and the latitude, from almucanter obser-vations and Talcott pairs, at 30deg. 46 minutes 1.84 seconds south. The final longitude in the observing pillar in the Kimberley, depending on 80 comparisons, has been fixed at 8 hours 30 minutes 5.46 seconds east of Greenwich, and the latitude from Talcott pairs at 16deg. 12 minutes 58.6 seconds south. The State's eastern boundary is defined by the 129th meridian of longitude, so that in the case of Deakin it lay 1 minute 50.85 sec-onds to the east of our observing pillar, and in the Kimberley 5.46 seconds of time or 1 minute 21.90 seconds west of the observing pillar."