ASTRONOMICAL DETERMINATION OF AZIMUTH AND LATITUDE BY OBSERVATION OF TWO UNKNOWN STARS WITHOUT TIME MEASUREMENT AND KNOWLEDGE OF ASTRONOMY

Survey Review ◽  
1991 ◽  
Vol 31 (242) ◽  
pp. 233-237 ◽  
Author(s):  
B. Buonocore ◽  
A. Vassallo
1972 ◽  
Vol 1 ◽  
pp. 27-38
Author(s):  
J. Hers

In South Africa the modern outlook towards time may be said to have started in 1948. Both the two major observatories, The Royal Observatory in Cape Town and the Union Observatory (now known as the Republic Observatory) in Johannesburg had, of course, been involved in the astronomical determination of time almost from their inception, and the Johannesburg Observatory has been responsible for the official time of South Africa since 1908. However the pendulum clocks then in use could not be relied on to provide an accuracy better than about 1/10 second, which was of the same order as that of the astronomical observations. It is doubtful if much use was made of even this limited accuracy outside the two observatories, and although there may – occasionally have been a demand for more accurate time, it was certainly not voiced.


2019 ◽  
Vol 50 (2) ◽  
pp. 221-248 ◽  
Author(s):  
Michael Kershaw

By the beginning of the twentieth century, the meridian passing though the Royal Observatory at Greenwich had become a near-universal reference for place and time. It was the zero of longitude. But our current standard of zero longitude is about 100 metres away from the original. That mobility needs historical context: Greenwich began to move in the years after the First World War, when wireless techniques for the astronomical determination of longitude and the standardisation of time were developed, and has carried on moving ever since. In this article, I describe how twentieth-century techniques for the determination of longitude not only brought improved precision but also led to fundamental changes in our long-standing conventions of longitude. And I show how – despite its mobility – our current standard of zero longitude continues to respect the original.


1956 ◽  
Vol 76 ◽  
pp. 105-105
Author(s):  
A. Wasserstein

In Vol. LXXV (1955) of the JHS I suggested that the determination of the angular diameters of the sun and the moon ascribed to Thales (Diog. Laertius I. 24) may have been obtained by angular measurement, not as is generally supposed by time-measurement. However, the question of the precise technical method that may have been employed was left open. To measure a very small angle with any degree of accuracy is obviously not easy; and a combination of actual measurement with calculation is probably necessary. In what follows I describe a method of measuring very small angles: whether this was the method employed in obtaining the result ascribed to Thales I do not know; all I can claim is that it presupposes neither mathematical knowledge nor mathematical techniques which could not have been at the disposal of an early Greek philosopher-mathematician.


Sign in / Sign up

Export Citation Format

Share Document