Abstract
THE TRANSIT OF VENUS OF 1874.—The reports and drawings of the New South Wales observers of this transit have already been published by the Royal Astronomical Society, so that the volume which we have received, containing the observations, published by authority of her Majesty's Government in New South Wales, cannot be looked upon as containing much that is new. Mr. Russell, the Government astronomer, under whose direction this work has been compiled, seems to have taken great pains in bringing it out, for besides a long introduction summing up the results, and separate accounts of each of the reports, the book is illustrated with several photographs and drawings, a frontispiece containing photographs of the observers, and is bound in a very elaborate cover. The value of this publication lies in the fact that each observer's record is published in full, and is accompanied by numerous printed diagrams, which help to make more clear the various descriptions of phenomena that were noticed. Passing over the observations of contacts, we may refer to some of the physical phenomena which seemed to have claimed attention. With regard, first, to the black drop, it seems that only those who were using telescopes of small aperture, 11 to 2 inch, and low power eyepieces, saw it, while on the photographs not the slightest trace of it could be seen. The evidence, as far as the New South Wales observations go, shows, as Mr. Russell states, that “the black drop does not seem to be due to the atmospheric conditions, but rather to the imperfections of telescopes of small apertures and low power.” The curious “faint tremulous shaking,” as noticed at the times of the planet's ingress and egress, are put down to the temporary unsteadiness in the atmosphere. Three important phenomena which seem to have been generally observed were the rings of light and the halo seen surrounding the planet, and the ring uf light round that part of the planet projected on the sky. Mr. Russell is of opinion that the atmosphere of Venus probably does not extend far enough to produce the observed phenomena of the halo, but, perhaps, a part of it could be attributed to the haze in the atmosphere caused by the forming of moisture at that time. The bright ring, described as very brilliant, was found to affect the chemicals more than the sun itself, as shown on the photographic plates; its brilliancy accounts for it being only seen on the limb not projected on the sun, and it is suggested that perhaps under favourable conditions this halo might be seen when the planet is lost in the sunlight.
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Our Astronomical Column. Nature 48, 447–448 (1893). https://doi.org/10.1038/048447a0
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DOI: https://doi.org/10.1038/048447a0