1825.] 



on the Planet Venus, 



41;^ 



fig. 4. Dr. Wasse observed them 

 with the same instrument, and 

 made a drawing, which coincided 

 with mine in all respects, except 

 he did not see tlie two bright 

 lines at a. In T' 30-, Dr. W. 

 and I both concluded that the 

 spots had approached the W 

 limb, and moved very little to- 

 wards the N horn. The planet 

 bad the same appearance with 

 both the aerial telescopes ; in- 

 deed with that of 50 feet, I cer- 

 tainly saw them more evidently than with the reflector. 



April 13, 4'^ 30"™, nearly 2i-^ before sunset, [ had a fine view 

 of Venus, which is represented in fig. 5 with the reflector, powers 

 70 to 400; with 70 I could not see any spots; with 120 they 

 were very distinct. Those towards the S were so considerable 

 that whilst some fleecy clouds were passing, the whole to the S 

 of the line a h disappeared, and that to the N remained visible 

 for some minutes. The evening unfortunately proved cloudy ; 

 had it been fine, I might have obtained useful information 

 respecting the time of rotation, as 7i hours would have been 

 allowed for observation ; and I the more regret it, because this 

 was the only time I saw Venus so early. Lieut. Hornby, RN. 

 observed the planet with me, and confirmed my drawing of the 

 appearances. • 



April 20, from 7'^ to 9*^. Venus 

 as in fig. 6 ; I used the reflector 

 and both aerials, and saw the 

 spots with all. The evening 

 being very fine, I saw the spots 

 better defined than usual ; yet 

 they were never so distinct as to 



allow the use of a micrometer with advantage. Between 7'' and 

 9^^, the bright ridge separating the two spots had evidently 

 moved ; the most S part had moved towards the W, and also a 

 little to the N. I can speak more confidently of the motion than 

 at any former time; and although they were not so well defined 

 as to allow measures to be taken which would determine either 

 the exact time of rotation, or the position of the axis, yet the 

 motion seemed so sensible as to agree with the time determined 

 by Cassini, and not to confirm that fixed by Bianchini. Beyond 

 this I could not arrive at any conclusion ; because Venus, 

 except observed when the sun is above the horizon, is always in 

 the worst part of the atmosphere, and of course appears tremu- 

 lous ; her light also is so very powerful that no telescope shows 

 her free from radiating light, which is a great impediment. 



