45+ Mr. Hamilton’s Account of the 
only circumpolar one my lituation enables me to fee an intire 
revolution of) and 1 found on inverting the axis that the error of 
collimation amounted to onlv 2" of time at the polar ftar. By an 
obfervation of the fun’s pafiage before thetranfit, the clock was 
flow - 2 1 ",7 ; and by an obfervation of the paffage of Lyra cor- 
rected flriftly by your tables, after the ingrefs of Mercury, the 
clock appeared to be 21 ",4 flow, its rate for the week lofing 
1 ",5 per revolution. I obferved with an achromatic tube of 
three inches aperture, triple object-glafs, and ufed a magnifying- 
power of about 90 times, which I preferred on account of the 
ilate of the atmofphere. At about two o’clock I fet a flop 
watch to apparent folar time, and placed myfelf at the tele- 
fcope within hearing of the beat of the tranfit-clock. I kept 
the part of the difk where I expedled the ingrefs in conflant 
view, my fight being directed by a vertical wire in the eye- 
tube, and at 2 h. 22' 3" I flopped the watch, and counted 20", 
to be fure of my having really perceived the fir ft impreffion 
(which I apprehend could not have been fhewn 1" fooner by 
the power, &c. I ufed). I then flopped feconds to the clock, and 
counted up to an even minute, and found, that the firfl external 
contact happened at 1 7 h. 33' 1 1 " by the clock, or 2 h. 2 1 ' 45" 
apparent time. Mercury came in like a diflindt black point, 
without any preceding hazinefs or appearance of atmofphere ; 
and at 1 7 h. 39' \o" by the clock, or 2 h. zf 43" apparent 
time, the thread of light feemed compleated, and then I date 
the internal contact. I had no inflrument fit to take any mi- 
crometer meafures, fo continued only looking at the planet till 
the fun got fo low r , that the limb p relented the appearance of 
a troubled fea at a diflant horizon, among the waves of which 
Mercury once more plunged at about 18 h. 52', and the fun and 
3 planet 
