VOL. LII.] PHILOSOPHICAL TRANSACTIONS. SQJ 



the form of a bergamot pear, or as Governor Pigot then expressed it, looked like 

 a nlnepin ; yet the preceding limb of Venus was extremely well defined. Mr. 

 Hirst suspected this appearance might be owing to their telescopes not being 

 nicely enough set to their focal lengths ; accordingly he took'care to try this seve- 

 ral times during the transit, but found it not to be the case ; for though the 

 planet was as black as ink, and the whole body truly circular, just before the 

 beginning of the egress, yet it was no sooner in contact with the sun's preceding 

 limb, than it assumed the same figure as before, at the sun's subsequent limb : 

 the subsequent limb of Venus keeping well defined and truly circular. 



The beginning of the egress, or 2d interior contact, was observed only by Mr. 

 Hirst and Mr. Call, Mr. Pigot having retired. This phasis came on at 1^ 39"^ 38^ 

 P.M. and the total egress by Mr. Hirst alone at I*' 55™ 44% apparent time, Mr. 

 Cal unfortunately losing the solar image out of the field of his telescope. 



LXllI. An Account of a printed Memoir ^ in Latin, presented to the Royal Soci- 

 etij intitled, De Veneris ac Solis congressu observatio, habita in astronomica 

 specula Bononiensis Scientiarum Instituti,die, 5 Junii 1761. Auctore Eustachio 

 Zanoito, ejusdem Instituti Astronomo, ac Regiceutriusque Londinciisis et Beroli- 

 nensis Academice Socio. By Nathaniel Bliss ^ Savilian Professor of Geometry , 

 and F.R.S. p. SQQ. 



The planet Venus has been so seldom observed in those circumstances, which 

 are of the greatest use in determining some of the most essential elements of its 

 motion, that all such observations, made by an accurate astronomer, cannot but 

 be very acceptable to the public. 



At Bologna on the night preceding the day of the transit, the weather was very unfa- 

 vourable; but early in the morning the clouds which covered the whole hemi- 

 sphere began to break, and were driven off towards the horizon by a gentle wind : 

 so that the observations were retarded only during the space of about half an 

 hour. Father Frisi, professor of mathematics at Pisa, and Signors Mathenci 

 and Marini, assisted in making the observations ; the two latter observing in the 

 upper room of the observatory, together with Mr. Professor Zanotti ; and Father 

 Frisi, accompanied by the two professors of mathematics Signors Casali and Can- 

 terzani, in a lower chamber. 



S. Zanotti, in order to determine the place of Venus on the sun, made use of 

 a quadrant of 2-i- feet radius, in the telescope of which were placed two wires, the 

 one in a horizontal, the other in a vertical direction : by observing the appulses 

 of the limbs of the sun and Venus to these wires successively, no error from re- 

 fraction can take place. 



When the planet drew near to the edge of the sun's disk, the observers pre- 



