ON THE VISIBILITY OT THE DARK SIDE OF VENUS. 403 



5. Count rriedrich Hahn, of Eemplin, Mecklenburg, saw the phenomenon 

 unusuall}- Avell and often during the spring and summer of 1793, in twilight 

 as well as in daylight. He employed excellent instruments, and gives a 

 very detailed description of what ho saw ; also two sketches. No other ob- 

 server seems to have seen the phenomenon so often and so well. (Berliner 

 astronomisches Jahrbuch fiir 17913, p. 188.) 



6. The venerable old selenographer Schroter saw the phenomenon only 

 once, February 14, ISOG, in faint twilight, with an excellent telescope, and 

 gives a very accurate description and sketch of it. lie remarked an im- 

 portant feature in the phenomenon : the limb of the dark hemisphere was 

 brighter than its central part. (Berliner astronomisches Jahrbxich fiir 1809, 

 p. 164, and Beobachtungen des grossen Cometen von 1807, Appendix, 

 p. 66.) 



7. Simultaneously with Schroter, and independently of him, C. L. Hard- 

 ing, at Gottingen, succeeded in observing the dark side of Venus on throe 

 different evenings — January 24, February 28, and March 1, 1806. On the 

 second of these days the light was reddish grey, and on all of them the 

 phenomenon was seen with the iitmost sharpness and distinctness. (Berliner 

 Jahrbuch fiir 1809, p. 169.) 



8. The well-known observer of the sun J, W. Pastorff, at Buchholz in 

 Prussia, saw the phenomenon (as he reports) many times so distinctly that 

 he could distinguish bright and dark patches in the faint grey light. Only 

 one date and a corresponding drawing are given, February 10, 1822, at 5 

 P.M., when the breadth of the crescent was 0'23 diameter of the whole disk. 

 (Berliner Jahrbuch fiir 182.5, p. 235.) 



9. June 8, 1825, at 4 a.m., almost in full daylight, the phenomenon was 

 witnessed by Gruithuisen at Munich. No particulars given. (Astronomisches 

 Jahrbuch fiir 1842, herausgegeben von Gruithuisen, p. 158.) 



10. The next observation was made by Mr. Guthrie, near Bervie, N.B. 

 (Great Britain), during the inferior conjunction in December 1842. Mr. 

 Guthrie saw a narrow fringe of light around the whole disk of the planet. 

 (Monthly Notices of the Eoy. Astr. Soc., vol. xiv. p. 169.) 



11. G. A. Jahn, at Leipzic, saw the dark side of Yenus on September 27 

 and 28, 1855, at 11 a.m., in broad daylight. (Jahn's Unterhaltnngen im 

 Gebiete der Astronomic, vol. ix. p. 320.) 



12. Mr. Berry, of Liverpool, saw the phenomenon on the evening of 

 January 14, 1862. (Month. Not. vol. xxii. p. 158.) 



13. Mr. C. L. Prince, of Uckfield, observed Venus almost daily during her 

 inferior conjunction between Sept. 23rd and 30th, 1863, in bright daylight, 

 and coitld trace on every day the whole disk, or at least a faint fringe of 

 light around the edge. (Month. Not. vol. xxiv. p. 25.) 



14. Mr. "VV. Engelmann, of the Leipzic Observatory, saw the phenomenon 

 repcatcdlj- — most advantageously, as it seems, on April 20, 1865, immediately 

 after sunset. The dark side was greenish grey, a little brighter than the sky. 

 (Astron. Nachr. No. 1526, vol. Ixiv. p. 223.) 



15. During the inferior conjunction of 1867 Venus was well observed by 

 Professor C. S. Lyman, of Yale College, Newhaven, U. S. The extension of 

 the crescent over more than 180° was seen during a period of eleven days : 

 on 10th and 12th of December the thin bri^ght crescent formed an unbroken 

 ring; on the day of conjunction (11th December) the close proximity of the 

 sun permitted no observation. (American Journal of Science, 2nd series, 

 vol. xliii. p. 129.) 



16. Mr. Th. Petty, of Deddington, near Oxford, saw the dark side of Venus 



