53 



OBSERVATIONS OF THE OCCULTATIONS OF JUPITER AND HIS 

 SATELLITES BY THE MOON, APRIL 24th, 1864. Lat. 42' 52^ 13" 

 S., Lon. 9h. 49m. 29s. 6 E. By F. Abbott, F. R. A. S. 



The sky on the morning of the 24th was alternately clear and hazy after rain 

 that fell on the previous night ; a few bands of strata clouds were dispersed 

 here and there which occasionally passed over the Moon and Jupiter, and at 

 times caused both the planet and its satellites to have an unfavorable appear- 

 ance for the occultation. 



The light of both Jupiter and the Moon, was seen at intervals with good 

 definition, but was notably less brilliant than could have been wished for at the 

 time of conjunction, notwithstanding the air was calm and undisturbed. 



Apparent conjunction of the — 



h. m. s. 



4th Satellite, 1st contact 6 19 40 a.nL 



„ Disappearance 6 19 41 7 „ 



3rd Satellite, 1st contact 6 20 24 2 „ 



„ Disappearance 20 26 8+ „ 



1st Satellite, 1st contact 6 22 20 „ 



„ Disappearance 6 22 21 9 „ 



Jupiter, 1st limb 6 23 35 5+ „ 



2nd ditto 6 25 24 8 „ 



Atmospheric pressure, 29.514 in. 

 Temperature, 47°. 



Shortly after the disappearance of Jupiter, small vapory clouds accumulated 

 and passed over the Moon, which prevented any observations being made on 

 the 2nd satellite and the emersions. 



The planet with the whole of its satellites passed behind the Moon in a 

 chord near the centre, and if the sky had been clear at the the time, both the 

 immersion and emmersion could have been correctly noted. 



Jupiter at the first contact on the enlightened limb of the Moon appeared of 

 a bluish-green color, and the out-line of the Moon's limb was at the time 

 affected with a tremvilous motion, which rendered the planet's actual immersion 

 doubtful to two or three seconds. After once on eluding upon its disappearance, 

 a portion of its disc seemed to reappear for an instant in the fluttering of the 

 Moon's edge. 



The telescope used on the occasion was an unexceptionably good 5-foot 

 achromatic with 4 inch clear aperture, power 135. Means for micrometer 

 measures were provided, but the sky at the time was unfavorable. 



The chronometer used was found by transit observation a few hours pre- 

 vious to be one second and sixty-seven hundredths fast (-1-1.67") which ii not 

 accounted for. 



Private Observatory, 

 Hobart Town, 1864. 



