VOL. LIX.] PHILOSOPHICAL TRANSACTIONS- 641 



tion of the transit of the present year seems to corroborate his assertion, in the 

 account of the transit observed in India, in 176I; however, he does not here 

 peremptorily assign the cause, leaving such remarks to be made by others. 



On his return from India, Mr. H. was glad to find he was not singular in e- 

 marking the strange phenomenon of the oblongation of the orb of Venus at the 

 time of both the internal contacts. It was with sensible pleasure he saw in the 

 Philos. Trans, that 4 astronomers at Upsal, in Sweden, as well as Mr. Dunn, 

 in England took notice of the same or similar circumstances. The appearance 

 of this protuberance or ligament must now be universally confirmed, especially 

 by all observers of the transit of the present year, at least by all such as have 

 viewed it through telescopes of sufficient magnifying powers, and who have sense 

 enough to believe their own eyes, or candour enough to embrace and acknow- 

 ledge conviction, malgre all prejudice and preconceived opinion. 



Fig. 3 represents the first presage Mr. H. had of the approach of Venus to 

 the sun's extemal disk. Fig. 4 is the appearance of the black notch, when he 

 noted the time of the first external contact. Fig. 5 is the body of the planet 

 within the solar disk, adhering to the sun's upper edge, the thread of light not 

 yet formed. Fig. 6 the protuberance forming, and the undulation at c, d, very 

 violent, better seen in fig. 8. Fig. 7 the undulation decreasing, and the pro- 

 tuberance forming itself into a point, the luminous filaments darting between 

 the edges of the sun and the planet. Fig. 8 the luminous filaments cease to 

 move, and the upper edge of the planet is well defined; its whole orb more 

 opaque, but not yet divested of its oval appearance, the thread of light at c, d, 

 is formed; and at this period he marked down the time of the internal contact. 

 Fig. 9 the planet is restored to its circular figure. 



XXXI I. Observations made at Leicester on the Transit of Fenus over the Sun, 

 June 3, 1769. El/ the Rev. Mr. Ludlam, Vicar of Norton, near Leicester, 

 p. 236. 



The telescope, used for viewing the planet, was made by Mr. Dollond, with 

 a triple object glass of 33^ inches focal distance, and was found by experiment 

 to magnify 54 times. The clock was firmly fixed; its pendulum rod was made 

 of wood. The transit telescope was not accurately adjusted either to the meridian 

 or horizon, but the transits of the sun and of *i Bootis were sufficient to show 

 the rate of the going of the clock, and the corresponding altitudes of the sun, 

 its error a few days before the transit of the planet; whence the necessary reduc- 

 tion of the time then shown by the clock to apparent time may be easily derived. 

 If we suppose then the clock to be 1™ 11' faster than mean time, on June the 

 2d at noon, and to gain at the rate of 2i seconds in a day, as deduced from 



VOL. XII. 4 N 



