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XLII. Account of the "Tran fit of Mercury, 
ohferved. at Norriton, in Pennfylvania, 
Nov. Qu 1769 agreeable to an Appoint- 
ment of the American Philofophical Society , 
held at Philadelphia, for promoting ufefid 
Knowledge. By William Smith, D. D . 
Provofi of the College of Philadelphia; 
John Lukens Ffq\ Surveyor General of 
Pennfylvania; David Rittenhoufe, M.A . 
and Mr. Owen Biddle. Communicated 
by Benjamin Franklin, LL. D. F. R. S. 
and Prefident of the Philofophical Society 
at Philadelphia. 
Read Dec. 13, A S tranfits of Mercury are more fre- 
/~\ quent than thofe of Venus, we need 
not be fo particular in this account, as we were in 
that of Venus. 
We had the fame telefcopes now as before, viz. 
1. The college reflector, with Dollond’s microme- 
ter; ufed by myfelf, with a magnifying power of 
200, to obferve the contacts. 
2. A refradtor of 42 feet, magnifying 140 times, 
ufed by Mr. Lukens. 
3. Mr. 
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