VOL. LIX.] PHILOSOPHICAL TRANSACTIONS. 683 



equal altitudes and meridian passage of the sun, to ascertain and regulate the 

 going of the clock ; 2d, zenith distances, for the latitude; 3d, the height of the 

 barometer (50 feet above low-water mark), also of the thermometer both within 

 doors and without. Hence it appears that the greatest height of the thermo- 

 meter was on the 3d of July, that within doors being at 70, and that without at 

 79 ; and the lowest state of the same was on Dec. 1 1 , the thermometer within 

 being — 31, or 31 below zero, and that without — 42. 



The 2d is another series of observations, of zenith distances with 3 different 

 sectors, and of the barometer and thermometers, also of the sun and different 

 stars being on the meridian. The 3d is a series of occultations of fixed stars by 

 the moon. The 4th is the series of observations on the transit of Venus itself, 

 being the grand object of the whole undertaking. These show the times of all 

 the 4 contacts, with the distances of the limbs of the sun and Venus, and the 

 diameters of both, observed at a great number of different times. The chief 

 results are, that the exterior contact at the ingress was observed at O^ 57™ 0.6' ap. 

 time, by J. D. (Jos, Dymond), but at O^ 57"" 7-6' by W. W. (Wm. Wales) ; the 

 interior ditto at l'' 15"' 21.3' by W. W., but at l'' IS*" 25.3' by J. D. Also at 

 the egress, the internal contact was at 7'' O" 45'4- by W. W., but 7'' 0™ 48'^ by 

 J. D. ; and external contact at 7'^19'° I'i by W. W., but at 7" IQ"^ 20^ 

 by J. D. 



Remarks. — The heavens at the beginning, and for a considerable time both 

 before and after, were frequently obscured by clouds ; but in the intervals, the 

 air was very clear, and the sun's limbs extremely well defined. Soon after Venus 

 was half immerged, a bright crescent, or rim of light, encompassed all that part 

 of her circumference which was off the sun ; thereby rendering her whole peri- 

 phery visible. This continued very bright until within a (ew minutes of the in- 

 ternal contact, and then vanished away gradually. They took, for the instant 

 of the first internal contact, the time when the least visible thread of light ap- 

 peared behind the subsequent limb of Venus: but before that time, Venus's limb 

 seemed within that of the sun, and his limb appeared behind her's in two very 

 obtuse points, seeming as if they would run together in a broad stream, like 2 

 drops of oil; but which, nevertheless, did not happen, but joined in a very fine 

 thread, at some distance from the exterior limb of Venus. This appearance was 

 much more considerable at the egress than at the ingress; owing, as appre- 

 hended, to the bad state of the air at that time. They took for the instant of 

 internal contact, at the egress, the time when the thread of light disappeared 



nical rising of the Pleiades, annexed to Dr. Vincent's Voyage of Nearchus, 1797. Besides these, 

 Mr. W. wrote some ingenious papers in the Phil. Trans., and in different periodical publications, 

 particularly the Ladies' Diaries, sometimes under the signature of his own name, and sometimes 

 under various fictitious signatures, as G. Cetii, Felix, M'Carthy, &c. 



4 S2 



