550 BIBLIOGRAPIIY OF HERSCHEL^S WRITINGS. 



Herschel, W. : Synopsis of the \Yritixgs of— Continued. 

 A. D. Vol. P. 



1792 82 23 Miscellaneous ohservalrons. By William Herschel, LL. D., F. R. S. 



Re.ad December 22, 1791 . 



23 Accoimt of a Comet. [1792, I.] This was discovered by Carolina 



Herschel, 1791, Dec 15. Examined Dec. 16 with a 20-ioot re- 

 flector; brief description and position for Dec. 16. 



24 0)1 the periodical appearance of o Ceti. 



25 331 days 10^ ig^ is its period. 



26 On the disappearance of the ^ibfh Herculis, 



1781, Oct. 10, I examined both .54 and 55 Herculis; again 1782, April 

 11 ; 1790, May 24, 55 Herculis was missingjiand although looked for 

 has not again been seen. 



27 Remarkable Phenomena in an eclipse of the Moon. 



1790, Oct. 22, when the moon was totally eclipsed I viewed Ihe disc 

 with a 20-feet reflector with power 360. In several parts of it I 

 perceived many bright, red, luminous points. Most of them w re 

 small and round, at least 150 of them. Their light did not much 

 exceed that of Moris Porphyrites Hevelii. 



We know too little of the surface of the moon to ventni'e at a surmise 

 of the cause from whence the great brightness, similarity, and re- 

 markable color of these points could arise. (Dated) Slough, De- 

 cember 17, 1T91. 



1793 83 201 Observations on the Planet Venns. By William Herschel, LL. D., 



F. R. S. Read June 13, 1793. 



201 A series of observations on Venus begun in April, 1777, has been con- 



tinued down to the present time. The hist object of the research 

 was to determine the diurnal rotation, for the observations of Cas- 

 SINI and BiANCHiNi can leave no doubt but that it has a rotation 

 on its axis; the second was the atmosphere of Venus, of tho exist- 

 ence of which, after a few months' observations, I could not enter- 

 tain the least doubt ; and third, the investigation of the real diani- 

 eter. To which may be added an attention to the construction of 

 the planet with regard to permanent api)earances, such as might bo 

 ascribed to seas, continents, or mountains. 



202 The result of my observations would have been communicated long 



ago if I had not flattered myself with the hope of some better suc- 

 cess concerning the diurnal motion of Venus, which has still eluded 

 mj' constant attention as far as concerns its peiiod and direction. 

 202 Even at this present time I should hesitate to give the following ex- 

 tracts if it did not seem incumbent upon me to examine by what; 

 accident I came to overlook mountains in this planet ^' of such enor- 

 mous height as to exceed four, five, or even six times ihe x>erpendicular 

 elevation of ChimboraQO, the highest of our viountains." [Quoted from 

 Schroeter, Phil. Trans. 1792, p. 337.] 



202 The same paper contains other particulars concerning Venus and 



Saturn. All of which being things of which I have never taken 

 any notice, it will not be amiss to show by what follows that neither 

 want of attention nor a deficiency of instruments could occasion my 

 not perceiving these mountains of more than 2'3 miles in height; this 

 jagged border of Venus; and these flat spherical forms on Saturn. 



203 Before I remark on the rest of the extraordinary relations above men- 



tioued I will give a short extract of my observations of Venus. 

 203 Observations from 1777, April 17, to 1793, May 20. 



