246 PEOCEEDINGS OF THii [NoV., 1890. 



Canadian Entomologist, Vol., XXII, No. 11. 



Nova Scotian Institute of Natural Sciences : Proceedings and 

 Transactions, Vol. VII, parts 1--3. 



Academy of Natural Sciences, Philadelphia : Proceedings, 1890, 

 part 1. 



Smithsonian Institution, List of Exchanges, and 

 Rules of International Exchange. 



Colorado College Scientific Society, Colorado Springs : College 

 Studies, 1890. 



Government Reports, Large Collection. 



The f ollovdng paper was read : 



THE ANNULAR PHASE OF VENUS. 



BY PROF. LEWIS K. GIBBES. 



An opportunity of observing an unusual, if not remarkable phenomenon, 

 will soon occur, and I wish to call the attention of astronomers to it, as another 

 opportunity will not present itself until after the lapse of eight years. This 

 phenomenon may be conveniently called the annular phase of the planet Venus, 

 though it be produced not by reflected light only, as in the ordinary phases 

 of the moon, but partly also by the refracted light of the Sun, which has 

 passed through the planet's atmosphere. This phase I unexpectedly witnessed 

 24 years ago under the following circumstances : 



I desired to observe the prolongations of the cusps of the crescent of light, 

 mentioned by several writers, and which I afterwards found had been observed 

 by Madler, in May, 1849, and used by him to obtain the amount of refraction 

 in atmosphere of Venus ; but I had not then read his paper on the subject, 

 and was unacquainted with his formulas. 



It was well known that if Venus and the Earth, at any time occupied certain 

 relative positions in their orbits, they would return very nearly to the same 

 points, after an interval of 8 years less 2i days. It was also well known that Ve- 

 nus would transit the northern part of the Sun, during the forenoon of the 9th 

 of Dec, 1874, (civil day at Greenwich), and would transit the southern part, 8 

 years less 2^ days later, or during the afternoon hours of the 6th of Dec, 1882 . 

 It was therefore evident, that it would pass north of the Sun, and very near it, 

 8 years less 24 days before the first of these transits, and would approach near- 

 est to the Sun, about 2 p. m., (Greenwich time ), on the 11th of Dec, 1866, 

 least distance of centres being about 38' of arc, I therefore prepared to observe 

 the Planet on the forenoon of that day. 



My observations were made in the open air, on the grounds of the College 



