C lop ) 
thefe three Trads, he did not well underhand the Ways-of 
working in fecond Differences. And this is further manifeft 
by the loth, nth, and Proportions of this third Trad. 
For thefe he lays down as the Foundation of his infinitefi- 
mal Analyfis in arguing about centrifugal Forces, and pro- 
pofes the firftof them with relation to the Center of Cur- 
vity of the Orb, but ufesthis Propofition in the two next, 
with Relation to the Center of Circulation. And by con- 
founding thefe two Centers with one another in the funda- 
mental Proportions upon which he grounds this' Calc ulus, 
he erred in the Superflrudure, and for want of Skill in fe- 
cond and third Differences, was not able to extricate him- 
felf from the Errors. And this is further confirmed by the. 
fixth Article of the fecond Track For that Article is errone- 
ous, and the Error arifcs from his not knowing how to ar- 
gue well abourfecond and third Differences. When there- 
fore he wrote thofe Trads he was but a Learner, and this- 
he ought in candour to acknowledge. 
It feems therefore that as he learnt the Differential Me- 
thod by means of Mr- Newtons aforefaid three Letters com- 
pared with Dr. Barrows Method of Tangents; fo Ten Years 
after, when Mr Newtons Principia PbifofophU came abroad, 
he improved his Knowledge in thefe Matters, by trying to- 
extend this Method to the Principal Propofitions in thar 
Book, and by this means compofed the faid three Trads. 
For the Propofitions contained in them (Errors and Trifles 
excepted) are Mr. Newtons (or eafy Corollaries from them) 
being publilhed by him in other Forms of Words before. 
And yet Mr- Leibnitz, publifhed them as invented by himfelf 
long before they were publifhed by Mr. Newton. Forin the 
End of the firft Trad, he reprefents that he invented them- 
all before Mr. Newtons Principia Thilofopbia came abroad, 
and fome of them before he left Paris, that is before Ofio*- 
beri6/6' And the fecond Trad: he concludes with thefe 
Words Mult a ex his deduci poffent praxi accommodate , fed no- 
