VOL. Lir."] I'HILOSOPHICAL TIIANSACTION-S. 0^9 



As it is to be feared that our other observers, Mr. Mason and Mr. Dixon, by 

 the misfortunes they have met with, have not been able to make their observa- 

 tions at Bencoolen, as was proposed ; Mr. M. humbly hazards an opinion, whe- 

 ther the difference in the total duration of the transit of Venus over the sun's 

 disk, observed in any two places, where it is likely observations have been made, 

 will be great enough to enable us to infer the sun's parallax with sufficient exact- 

 ness, or even nearer than it is known already. So that he is afraid we must wait 

 till the next transit in 17^9, which is, on many accounts, better circumstanced 

 than this, before astronomers will be able to do justice to Dr. Halley's noble 

 proposal, and to settle, with the last and greatest degree of exactness, that curi- 

 ous and nice element in astronomy, the sun's parallax, and thence determine the 

 true distance of all the planets from the sun, and from each other. 



Mr. Maskelyne excuses himself that he does not at present attempt to deduce 

 any consequences from the above observations, not only as he was in want of others 

 corresponding to them made in other places, but also as he was not yet able to 

 settle the longitude of this place to sufficient exactness ; though he was of opinion 

 it cannot differ much. Mr. M. had not been able to get one observation of an 

 eclipse of Jupiter's satellites, though he was ready to seize any opportunity, if it 

 had offered; the very cloudy weather, which prevailed at the time, which is the 

 winter there, depriving him not only of these, but almost all other observations. 



XXXFII. Account of the same Transit. By the Rev. Richard Hay don. p. 202. 

 Mr. Haydon's latitude, at Leskeard, was 50*^ 1& 55", and his longitude west 

 of London in time, l6™ 10^; though he, from a memorandum he made some 

 years ago, supposed it near 2 minutes more. 



^. By correspondent altitudes of the upper limb of the sup, June 5 th, 176j, his 

 clock was too fast in apparent time g^ 30\ By the same, June 6, it was 

 Q^ 40^ 



June 6th, 1761, the diameter of © was 31' 3\".5 



and the diameter of 9 - • • • O SQ'-'.O 

 The nearest distances of Venus from the sun's limb ; the diameter of Venus 

 included. 



By tbe clock. Angular value. 



At 5^ 34"* 54^ 5' 5\".Q ) Semidiameter of Veuus to be deducted for the path of 



5 53 O 5' 38 .7 ] the centre. 



By the clock. Angular value. 

 At &" 13"^ 2* 5™ 15M 



6 31 24 4 40.8 



d 54 54 4 22.0 



♦ 7 28 19 3 0.5 



