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Meridian observations with the Hobart transit instruments

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posted on 2023-11-22, 10:44 authored by Henry Charles Kingsmill
The object of my paper is to bring under your notice a piece of astronomical work done at the Hobart Observatory, in the first instance by myself, and afterwards more completely by Captain Cust, of the Dart. This work was the determination of the meridian of the Hobart transit instrument by means of star observations taken with the instrument itself. The American astronomers determined a meridian with great accuracy when they came here on the transit of Venus expedition, and it would be possible to draw a parallel to it by offsets, as the Hobart Observatory is only 57ft. west of their meridian. But this method would be far less accurate than the determination of a fresh meridian by independent observations.
There is a meridian mark for the Hobart transit instrument near Mount Nelson, just above the rifle range, and a little to the east of it. A stone something like a milestone has been erected in brickwork with a crosscut in it to indicate the exact meridian. When I came to the Observatory I was told that the cross was wrong, and that the true meridian was close to the eastern edge of the stone, but there was no record of the exact amount of the error. To obtain the exact local time it is necessary to find out all the errors of the instrument. It is by a number of small corrections that accuracy is obtained. However, this error appeared to require a pretty large correction. In December, 1893, I took some observations of the Southern Pole Star and Octantes which,satisfied me that the true meridian was clear of the stone altogether and to the east of it.

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Papers & Proceedings of the Royal Society of Tasmania

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vi-ix

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In 1843 the Horticultural and Botanical Society of Van Diemen's Land was founded and became the Royal Society of Van Diemen's Land for Horticulture, Botany, and the Advancement of Science in 1844. In 1855 its name changed to Royal Society of Tasmania for Horticulture, Botany, and the Advancement of Science. In 1911 the name was shortened to Royal Society of Tasmania..

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