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Graphic: An Encyclopaedia of New Zealand 1966.

Warning

This information was published in 1966 in An Encyclopaedia of New Zealand, edited by A. H. McLintock. It has not been corrected and will not be updated.

Up-to-date information can be found elsewhere in Te Ara.

ASTRONOMY

Contents


Standard Time

Daily life in the early days of the colony did not require high accuracy of timekeeping, and it appears that each district kept its own approximate local mean solar time. Development of coastal shipping, trans-Tasman steam services, railways, and the electric telegraph soon showed the necessity of some kind of uniform time system for the country, if confusion was to be avoided. On the recommendations of Sir James Hector, the House of Representatives resolved that the mean time for the colony should be 11½ hours in advance of Greenwich mean time as from 2 November 1868. It is interesting to note that not long afterwards discussions arose as to whether or not it would be better to make this time difference exactly 12 hours. After the vicissitudes of “summer time” experiments, the standard time at present is in fact 12 hours ahead of Greenwich, as defined by the Standard Time Act of 1945.

Time and longitude are two completely interwoven quantities both for the navigator and for the surveyor; and it was soon appreciated that not only was it necessary to have a uniform time system for the young colony but also that the longitude must be known as accurately as possible. While fixing the location of the country accurately on charts, longitude relates its time to that of the prime meridian of Greenwich. It was, therefore, natural that much effort was expended in attempting to determine the longitude of Wellington, which from 1870 was the location of a time observatory.

Before the advent of radio or submarine cables, longitudes were determined whenever possible by the transport of chronometers between a known and an unknown position. Thus the Sydney-Wellington longitude difference became the subject of intensive study. The first attempt of this kind was made by the survey ships HMS Acheron (see Ships, Famous), and HMS Pandora from 1848 to 1854. There follows a long history of various repeated attempts to check and improve the values obtained, mostly by Lands and Survey Department officers. The devotion and interest of these men are an inspiration to anyone interested in this type of work. Completion of the trans-Pacific cable in 1902 enabled Dr Otto Klotz of Canada to bring this period to a close. Since then, three other determinations have been made, in 1926, 1931, and 1957, using radio time signals. In these years New Zealand participated in an international campaign for longitude determinations covering the entire world.

Despite the accepted necessity for a time service, particularly in a period when radio either did not exist or was in a very new state, there was no full professional time-service observatory until 1912, when the late C. E. Adams was appointed Government Astronomer. Previously the Ven. Archdeacon Stock, followed by Thomas King, a business accountant, made transit observations virtually in their spare time. With the retirement of Adams in 1936, officers in charge of the time observatory have not been given the title of Government or Dominion Astronomer.

By 1914 radio time signals, originating from the world's large observatories, began to make their appearance, and in the course of time it seemed unnecessary to make actual astronomical observations for the national time service. While from a severely practical point of view this might still be the case, scientific advances of the present day have indicated the necessity of resuming precision star observations for, among other things, the study of the finer motions of the earth. Stimulated by the International Geophysical Year (1957–58), the Department of Scientific and Industrial Research installed the most up-to-date instrument available, a Danjon astrolabe, for this purpose. This instrument, combined with a quartz-clock, means that the timeservice observatory is now well prepared to commence valuable observations of the highest international standard in this field.

Last updated 22-Apr-09