History of Astronomy by George Forbes

Author:George Forbes [Forbes, George]
Language: eng
Format: epub, pdf, mobi
Publisher: Public Domain Books
Published: 2005-05-01T10:00:00+00:00

FOOTNOTES:

[1] In 1480 Martin Behaim, of Nuremberg, produced his astrolabe for measuring the latitude, by observation of the sun, at sea. It consisted of a graduated metal circle, suspended by a ring which was passed over the thumb, and hung vertically. A pointer was fixed to a pin at the centre. This arm, called the alhidada, worked round the graduated circle, and was pointed to the sun. The altitude of the sun was thus determined, and, by help of solar tables, the latitude could be found from observations made at apparent noon.

[2] See illustration on p. 76.

[3] See Dreyer’s article on these instruments in Copernicus, Vol. I. They were stolen by the Germans after the relief of the Embassies, in 1900. The best description of these instruments is probably that contained in an interesting volume, which may be seen in the library of the R. A. S., entitled Chinese Researches, by Alexander Wyllie (Shanghai, 1897).

[4] Sir George Airy was very jealous of this honourable title. He rightly held that there is only one Astronomer Royal at a time, as there is only one Mikado, one Dalai Lama. He said that His Majesty’s Astronomer at the Cape of Good Hope, His Majesty’s Astronomer for Scotland, and His Majesty’s Astronomer for Ireland are not called Astronomers Royal.

[5] Annals of the Cape Observatory, vol. x., part 3.

[6] The parallax of the sun is the angle subtended by the earth’s radius at the sun’s distance.

[7] A. R. Hinks, R.A.S.; Monthly Notices, June, 1909.

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