lli tSlliLbsbtHICAL TRANSACTIOXS. [aNNO 1770- 



and that, like Mozart, he used to try their effect immediately on a spinnet, 

 which was in his bedchamber. 



IX. A Determination of the exact Moments of Time when the Planet Venus 

 was at External and Internal Contact with the Suns Limb, in the Transits of 

 June 6, 1761, and June 3, 1769' By Samuel Dunn. p. 65. 



'' The telescope being properly adjusted, and having a most clear and distinct 

 sight of the sun's limb where the external contact was expected to happen; at 

 1 1** sd™ 32' per clock, (which, reduced by the Astronomer Royal to apparent 

 time, is 7^ 10*" 33') while Mr. D, was moving his eye gently along that part of 

 the sun's limb where the contact was expected, there appeared as though a kind 

 of liicid wave of transparent matter, of the colour of that part of the lucid an- 

 nulus (which afterwards appeared round Venus), which was nearest to the limb 

 of Venus, and taking up the space of about a 5th part of a minute of a degree 

 along the sun's 6dge, this lucid wave seemed to strike gently against thte sun's 

 limb, and in an instant the little tremulous vibrations on the sun's limb were to- 

 tally stopped, and that part of the limb was rendered thereby a little obscure. 

 A second and half of time after this, at the same place of the sun's limb, arose, 

 first gently, and then more violently, a ferment, or boiling-j very different in 

 polour as well as magnitude, from the tremulous vibrations at other parts of the 

 ^un's limb, for it was darker and much morp violent, and at u'' 36'" 36' per 

 clock, or 7^ 10™ 37* apparent time, ^h''^ fermentation was enlarged along the 

 limb of the sun, and the limb "^ V^enus was entering on the sun's limb. 



Mr. D.'s attention b-'^g ^t this time engaged in examining the place around 

 the point of cor-^'^^^f he endeavoured to see a kind of brown penumbra precede 

 the lim'^ ^' Venus, but saw none; instead of it, a kind of whitish light, at first 

 . Vfiy faint, and afterwards as it advanced on the sun's disk becoming more strong 

 i)receded the limb of the planet; which light gradually diminished nearer to 

 Venus, and formed a narrow margin of lucid matter, by which the limb of the 

 planet became a little ill defined. Almost the same circumstances happened in 

 the exterior contact 1761, but with this difference, the lucid border then follow- 

 ing, the limb of Venus was more clear and transparent. Mr. D. was the more 

 particular in these circumstances, to be able to determine what differences might 

 arise from observation's made with telescopes and eyes equally good, and con 

 eluded from the phenomena, that two such observers, with but little inequality 

 in their judgments, might differ from each other 10 seconds of time. Before 

 this contact and a little after it, he endeavoured to f^nd a faint illumination on 

 the exterior limb of Ven^is; but could find none, till the time of internal contact 

 drew near. Another circumstance attending the phenomenon was this; the 

 limb of Venus which first entered on the sun's disk appeared to be the arch of a 



