( rji ) 
narrower. This our Author maintains to be ofcnec 
falfe, than true, and endeavours to (hew from his 
Theorem above-mention’d , that making the Outlet 
narrower, will frequently caule the rman f^elocitf of the 
Waters to become left than it was before. But whe- 
ther a Propofition of fuch Confequence, and fecraingly 
fo well rupported by Reafon and Experience, ought 
to be condemn’d upon the Authority of a Theorem 
founded only upon a tentative Calculation, mud be 
left to the Judgment of the Learned. 
II. Apollonii Pcrgaci Conicorum tihri OSio, Se- 
reni AncilTenlis de SeEitone Cylindn ^ Coni Libri 
duo. FoL B Theatro Oxon. 1 7 1 o. 
T he worthy Curators of the Orfard PVefs having 
obliged the Publick with a very elegant Edition of 
the Works of Euclid^ Graeco- Latine, were pleas’d fur- 
ther to proceed in the laudable Intention of giving the reft 
of the ancient Greek Mathematicians in the fame beautiful 
Form; In this Delign they were chiefly animated by the 
late learned and beneficent Dean of Lhrifi Churchy Dr. Henry 
Aldridge, who pitching upon Apollonius, as moft proper to 
fucceed Euclid, engaged the two SavtUan PrefeHTors to take 
upon them the Care and Pains of the Edition ; Dr. David 
Gregory promtfing his Affiftance as to the fiift Four Books, 
which are fti’l extant in Greek ; and Dr. Edm. Halley under- 
taking to franfiate the Fifth, Sixth, and Seventh Books out 
of Arabick ( in which Language they were only to be 
found ) and to endeavour to reftore the Eighth, long fince 
wholly lort. But T>:. Gregory foon after dying, the Care 
of the Whole devolved on Dr. Halley, who hath fpared no 
Pains to render the Work complete. 
He in his Preface tells us what Helps he had to perfed 
the Text, That he had the ufe of two Greek MSS. of the 
ftrft Four Books, one of which was Sir Henry Savil's, and 
is in the Suvilkn Study at Oxford, the other is now in the 
Roy.al 
