VOL. LX.] PHILOSOPHICAL TRANSACTIONS. 1$. 



very small circle, but as the planet advanced onward on the solar disk, that suvne 

 preceding part of Venus appeared to enlarge and expand itself, and the subse- 

 quent part of Venus, which was on the sun's limb, appeared as though it was the 

 portion of a smaller circle; and thus the planet appeared to the time of central 

 ingress, at which time half the planet appeared a semi-ellipsis, the conjugate 

 diameter forming the notch in the sun's limb. After the time of central ingress, 

 while the latter half of the planet was passing over the sun's limb, the like ap- 

 pearances occurred; so that, though that circumference vas really concave to 

 Venus's centre, a little after the central ingress, it appeared a little convex to 

 that centre, and so the planet advanced, that part of it which was nearest the 

 sun's limb appearing contracted, but enlarging itself a little farther on the disk. 

 >nThe planet being considerably past the central ingress, and being at broad 

 black contact with the sun's limb, but of an irregular form on awount of the 

 above-mentioned circumstances, and it being hard to judge what kind of contact 

 would appear, Mr. D. perceived a very faint luminous crescent exterior to the 

 limb of the sun; and nearly coinciding with the preceding limb of Venus conti- 

 nued over the sun's limb. This crescent was very faint, but steadily defined at 

 certain fits and returns till 7** iS"" 30' apparent time. When this crescent being 

 come near to the limb of the sun it vanished, and seemed to fall in with a kind 

 of confused slight illumination in the limb of the sun itself, where the internal 

 contact was to happen. At the same time a kind of partial and very feint illumi- 

 nation took place, both a little without, and a little within the sun's limb, as 

 well as in the limb itself, where the contact was to be, and a gentle ebullition or 

 boiling arose a little without the sun's limb on the limb of Venus, which con- 

 tinued till the dark body of the planet was wholly within the sun's disk, or 7^ 

 29"" 28" apparent time, when Venus's circumference was not passed coinciding 

 with the sun's circumference above 3 or 4 seconds of time. While attentively 

 viewing this, and judging it difficult to determine the exact moment of circular 

 contact, on account of the circumstances described, the ebullition or boiling be- 

 tween the limb of Venus and the sun became more violent, and the partial illu 

 mination increased; and at 7^ 29'" 38' he saw the planet as it were held to the 

 sun's limb by a ligament formed of many black cones, whose bases stood on the 

 limb of Venus and their vertexes pointing to the limb of the sun. These cones 

 put on various positions, and as Venus advanced they alternately contracted them- 

 selves towards the limb of Venus, and expanded themselves towards the sun's 

 limb, performing their undulations always regularly and in the same time as the 

 planet advanced on the disk, till 7^ 2Q'^ 48' apparent time. At the end of this 

 interval, the agitation or fermentation was exceedingly violent, for the whole 

 limb of Venus would sometimes librate towards the limb of the sun, and some- 

 times the limb of the sun would turn convex in yielding towards Venus; but the 



