Saturday, 1 May 2021

An Eclipse Observed in Ceylon with a Cooke

 

An Eclipse observed in Ceylon with a Cooke 

Englishman's Overland Mail Wednesday 27th December 1871


The Eclipse as Observed in Ceylon

The solar eclipse on December 12th 1871 was most favourably observed at all the stations occupied by the scientific party under Mr Lockyer’s direction as well as by Mr Janssen. Important scientific results may be expected to be shortly made known as indicated in the the message from Mr Lockyer.

Here in Colombo the weather during the eventful morning was all that could be desired, but being beyond the line of totality and shadow no special scientific value can be attached to the highly interesting observations made here by several gentlemen.

Our column this time will be unusually full of information respecting the eclipse and the special expeditions sent from home to observe it. About 3.5 inches of rain fell in Colombo between 8 00 pm on the 11th and 5.00 am on the 12th. We add the results of local observations:- the Sun rose obscured by clouds, which cleared off by about 6.30 .The whole surface of the Sun presented the usual strippled broken appearance, with here and there large spots. In the neighbourhood of these spots the strippling was more apparent than over the parts free of spots, but they came out in bold relief on the part of the Sun close to the Moon’s limb. Probably this increase of distinctness was caused by contrast of the black spot &c of the dark limb of the moon. This could not be seen through the 3-inch telescope. Some little time before the greatest obscuration a halo was visible around the sun, which gave place to short bright rays. This latter appearance was probably an ocular deception, as no trace of it was visible through the 4.5-inch telescope under a low power.

At the greatest obscuration no trace of corona was observable through the same instrument, with a solar eyepiece with a power of about 30. This was carefully looked for. The unobscured portion of the sun, about 15-16ths of its disc, was well defined, without appendages of any kind. Towards the time of centrality the diminution of daylight was very conspicuous—going from the open air into the house it was very striking. Standing in the centre of the room, and looking through the open window, the sun-shine outside was of a neutral tint. The crows commenced to assemble on the tree-tops, cawing after their usual fashion, when preparing for their night's rest. The planet Venus, high in the sky, was distinctly visible to the naked eye, and Jupiter, low down in the western horizon, was plainly discernible with the aid of an opera-glass. The thermometer at the commencement of the eclipse indicated 91.5 °F in the sun. At 7-15 it showed a rise of 2.5 degrees and at the greatest phase it had fallen to 84.5°. In the shade it stood at 76 degrees; at 6-45 and at the greatest obscuration at 75° At 9-10, with the full blaze of the then unobscured sun, the thermometer indicated 113 °; in the shade 81°.

Mr. Van Dort, of the Surveyor- General's Department, with the aid of a 3-inch telescope, power 50, made some careful drawings of the different phases of the eclipse. The attempt to take the time of first contact and the ending of the eclipse proved abortive. An ordinary watch was the only time- keeper at hand.

Instruments used in the above observations : Equatorial Telescope by Cooke and Sons, of York, 4.5 inches clear aperture, 66 inches focal length. Telescope by same makers, 3 inches clear aperture, 42 inches focal length, mounted on tripod stand."

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