VOL. LIX.] PHILOSOPHICAL TRANSACTIONS. 657 



And if Venus takes 1 9" from the first impression to the internal contact, the transit 



began at 6* 53"" 13' 



Seen going till the sun set in a cloud near the horizon 8 24 39 



When near the horizon, Venus's edge was full of notches and protuberances, 

 and she appeared as if moving round like a wheel. 



Eclipse of the Sun, June 4, common reckoning. 



Beginning of the eclipse - &' 27"' 50* 



Eclipse ended 8 15 JO 



There was an evident irregularity in the under edge of the moon, which entered on the south side 

 of the sun, and traversed it from south to north. 



The clock 18^ slow, to be added to the several observations. The internal 

 contact is, when the thread of light was completed. From the above obser- 

 vation, and from every one of any credit, the Hawkhill gentlemen appear to be 

 late in the external contact. 



XLV. Observation of the Transit of Fenus, and other Astronomical Observe 



tions made at Gibraltar ; By Lieut. Jardine. p. 347. 



To regulate the clock, an equal altitude instrument was fixed, nearly such as 



is described in Smith's Optics, vol. 2, p. 328, on which was mounted a small 



telescope with cross hairs, and the altitudes observed of the sun's upper and 



lower limbs. 



Transit of Venus. 



By 3 observers, with two T\ feet refractors, and one 2 feet reflecting telescope. 



June 3, Venus's 1st extewial coniact with the sun, at 6* 49" 58' 



1st internal contact with the sun, at ... . 7 7 11 



Sun set behind a hill 7 8 3 



Clock before mean time 1 8.8 



For the latitude of the place, they observed by a Hadley's quadrant, divided 



into minutes, the double meridian altitudes of Jupiter and Cor Scorpii, reflected 



from water. And for the longitude of the place, they observed several eclipses 



of Jupiter's satellites. 



Eclipse of the Sun. 



June 4, First contact at 6* 6°' 54' seen perhaps a little too late. 



Last contact at 7 '9 28 exact. 



Clock before mean time I 9 



Elev. of O's limb by Hadley's quad, at j JJ ^"j^J^ Vs *55 \^^^ ''""• 

 Dip of the horizon, for 160 feet above the level of the sea is to be allowed. 

 Remarks by the Astronomer Royal. 

 By re-computing these observations, I find, that the external contact of 

 Venus happened at S"" 51"" 8', the internal contact at 7'' 8" 21', the beginning of 

 the eclipse of the sun at 18*" 8 O', and the end at IQ*" 20"" 33 , all apparent 

 time ; and that the latitude of the place, by the mean of the 4 altitudes of 

 Cor Scorpii, is 36° 4' 44", n. The dip of the horizon of the sea, for an eleva- 

 tion of 160 feet, may be reckoned 12' 5*. Nevil Maskelyne. 

 VOL. XII. 4 P 



