146 



ASTRONOMICAL OBSERVATIONS 



III. Observed Occultations of fixed Stars at Hudson Observatory. 



No. 



Date. 



star. 



Immersion. 

 Siderial Time. 



Emersion. 

 Siderial Time. 



Remarks. 





1839. 











1 



Oct. 17 

 1840. 



6 Capricorni 



21>'56™48'.79 



22h 10" 7^79 



Imm. pretty good; Em. tolerable. 



2 



April 11 



a Leonis 





10 48 13.54 



Tolerable observation. 



3 



" 19 



•f Scorpii 



16 36 44.15 



17 33 50.65 



Imm. uncertain to 2^ or 3"; Em. good. 



4 



May 6 



/*' Cancri 



11 32 43.00 





Good. 



5 



(« it 



* 7 Mag. 



11 37 42.20 





Good. 



6 



Oct. 13 



r; Phiadum 





20 29 .12.94 



Perhaps 3' or 4' late. 



7 



Nov. 2 



i Capricorni 



20 44 50.52 



22 1 19.57 



Imm. tolerable; Em. perhaps 25late. 



IV. Second Comet of 1840. 



On the 14th of March, 1840, 1 received a letter from Mr. S. C. Walker, con- 

 taining the elements of two comets recently discovered at the Berlin Observa- 

 tory by Mr. Galle, accompanied by an intimation that one of them might be 

 still visible. I immediately computed an ephemeris, and on the first succeed- 

 ing pleasant evening, the 18th, readily found it nearly in the place expected. 

 I observed it afterwards, on the 19th, 21st, and 25th of March, as, also, on the 

 1st and 2d of April. After this there was no clear evening until the 7th, when 

 I searched for it in vain. The atmosphere was quite transparent, and there 

 was nothing to interfere with observations but the moon, now five days old. I 

 did not search for it afterwards. When first discovered, the comet was faint, 

 but brightest in the central parts, resembling a small nebula, nearly circular, 

 and about one minute in diameter; but its margin was exceedingly ill-defined. 

 On the 19th the nucleus was remarked to be somewhat eccentric, and on the 

 lower side of the comet, as seen in an inverting telescope. No remarkable 

 change in the comet's appearance was subsequently observed, except that its 

 brightness diminished somewhat more rapidly than had been anticipated. As 

 it would not bear an illumined field, I could make no use of the spider-line 

 micrometer, and was compelled to confine myself to a more inconvenient and 

 less satisfactory mode of observing. For right ascension, I brought the comet 

 into the middle of the field of the equatorial, and counted the seconds elapsed 

 betw^een its egress from the field and that of some neighbouring star. This 

 process was repeated six or eight times. For declination, I again brought the 



