C 315 ] 
telefcopCj and turned to the clock, to note this 
“ time for the contad, which was 2^ 12' 5^'. About 
fooner than this (being doubtful to two or 
“ three feconds at firft) was the firfi impreflion I 
“ faw on the limb ; which I have marked accord- 
“ ingly at 2^ 40'’ to 43'^ If this fird: impref- 
“ fion is to be taken for the external contad, I think 
“ it might be judged of to a lingle fecond of time; 
which one could not do by feveral feconds, either 
“ with refped to the internal contad, or even with 
“ refped to the moment of the diftind black dent 
“ made at the external contad, both which are far 
“ from being inftantaneoufly perceptible. Whether 
“ a telefcope of larger powers than what I ufed 
“ might not have fliewn this firfi; impreffion fooner 
“ (be it an atmofphere or whatever elfe), I will not 
determine ; though from Mr. Rittenhoufe’s time 
“ I think it probably v/ould* But I am fure that I 
“ faw the firfi flroke that was perceptible through 
my telefcope, and might have noted it to a fingle 
“ fecond, had I expeded it in that way. 
As to the internal contad, the thread of lightj 
coming round from both fides of the Sun’s limb, 
“ did not clofe infiantaneoufly, but with an uncer*. 
“ tainty of feveral feconds, the points of the threads 
“ darting into each other, and parting again, in a 
“ quivering manner, feveral times before they finally 
“ adhered. I waited for this adherence with all the 
“ attention in my powers and noted it down for the 
“ internal contad at 2^ 29' 5^^, a few feconds later 
“ than Mr. Lukens, who took the fame method of 
judging. 
Having 
S s 2 
