IT 



conjunctions, or iSve times 584 days, which is equivalent to 

 2,920 days, or eight years, the conjunctions are reproduced 

 almost on the same day and in the same part of the heavens. 

 The latitude of Yenus and the sun however are not rigorously 

 identical at the end of eight years, but present a difference of 

 20' to 24', therefore making a difference in 16 years of from 

 40' to 48', a quantity which surpasses the semi-diameter of the 

 sun ; these intervals therefore do not return again for more 

 than a century, when they succeed each other as before. 



In the year 1627 Kepler completed the Eudolphine tables 

 which enabled him better to calculate the motions of the 

 planets. In 1639 the planet Yenus passed over the sun's disc, 

 and on this occasion the transit took place unknown to any 

 notable astronomer. It was only seen by two young amateurs, 

 Jeremiah Horrocks, of Toxteth Park, near Liverpool, and 

 William Crabtree, of Broughton, near Manchester. In taking 

 the mean between the Eudolphine tables and those of Lans- 

 burg, Horrocks arrived at the position and time of both 

 ingress and egress of the planet's transit over the sun's disc 

 at 3h. 15m. p.m., on observing which it seemed to him at the 

 moment as if Divine Providence had encouraged his aspira- 

 tions in this most gratifying spectacle, the object of so 

 many earnest wishes. This was the first recorded time the 

 planet Yenns was seen crossing the sun's disc. At this time 

 Horrocks was but twenty years old, and he died three years 

 afterwards. His companion, Crabtree, lived but a short time 

 after him, when the world lost two young men of extra- 

 ordinary promise, who have left an interesting account of this 

 transit entitled " Venus in Sole Visa." 



The earth passes her ascending node in the beginning of 

 December, and her descending node in the beginning of June. 

 If to the date of the first transit seen by Horrocks and Crabtree, 

 December 4th, 1639, we add 235 years, it will give the time of 

 the forthcoming transit in December, 1874, at the same node. 

 Prom her inferior to her superior conjunction, Yenus appears 

 on the west side of the sun, when she is a morning star. From 

 her superior to her inferior conjunction she appears on the 

 east side of the sun, and is then an evening star, alternating 

 morning and evening star for a period of 292 days. Each 

 time Yenus never departs quite 48° from the sun ; she is never 

 seen at midnight, nor in opposition, being visible about three 

 hours before sunrise, and about the same time after sunset. 



The physical emanations in the sun are known to undergo 

 remarkable changes, these emanations are to be found in the 

 aurora, the zodiacal light, meteorides, etc. ; the chemical 

 emanation by which photographic impressions are produced, 

 observed with the refracting telescope, requires a peculiar form 



