Discussion of observations of the transits of Venus in 1761 and 1769 Volume 2, pt. 5 - Tapa blanda

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1890 Excerpt: ...Nairne jndged the internal contact, and thought the thread of light just ready to be formed, but did not see it completed, at 12h 15' 48", or 7h 29' 2oJ" apparent time. During these observations the air was very clear, with a west wind, and the Sun very distinct for the altitnde. A little after the internal contact 1 measured Venus's horizontal diameter with the achromatic object glass micrometer, applied to the 2-foot reflecting telescope, and found it to be 55$", by a mean of 8 observations, the extremes differing 4" from cue another, Venus at the same time ill-defined, and her circumference undulating very much. These observations belong to 1761, having been accidentally misplaced. % LONDON (MIDDLE TEMPLE). Philosophical Transactions, 1769, p. 171. Observer, J. Horsfall.--At 7h 26' 34" be saw a lambent light whirl around the opaque limb of the planet, the Sun being at the time only one-fourth of a degree above the top of the chimney. LONDON (SPITAL SQUARE). Philosophical Transactions, 1769, p. 192. Observer, John Canton, M. A., F. E. S.--About half a minute before the total ingress, when the bright cusps of the Sun were at some distance from each other, there appeared a faint light between them, a little lower than the cusps or nearer to the center of the planet. This I observed to increase till the time of the internal contact, which fully convinced me that there is an atmosphere about Venus. h.'" First external contact at 7 8 28 mean time. First internal contact at 7 26 59"" Duration of the ingress 18 31 The observations are expressed by Canton in Greenwich mean time. The conditions would seem to have been favorable and the time well determined. There is no certain statement of the phase observed; but from the gr...