12.G Remarks on Dr. Enfield^s tnstiiutcs 



works on the same subject which appeared m the former 

 part of the last century. The Hydrostatics, Prfeumatics, 

 and Optics, are chiefly taken from Dr. Rutherforth ; as is 

 also the Astronomy, with the exception of the four last chap- 

 ters of Part II., which are borrowed from Rowning. The 

 Mechanics does not appear to have been derived so exclu- 

 sively from any single source. It is apparent, however, that 

 Rutherforth furnished the arrangement. The filhng up is 

 from various authors. The chapters on the perpendicular 

 and oblique descent of falling bodies, the vibration of pen- 

 dulums, (excepting the cycloidal theory taken from Row- 

 ning,) and the motion of projectiles, are chiefly from Helsham. 

 A considerable portion of the concluding section on cen- 

 tral forces, is copied, nearly in its original form, from the 

 Principia. The few pages of the original work devoted 

 to Magnetism and Electricity, we presume, were written a- 

 new by Dr. Enfield ;~but the additions made by the Edit- 

 or of the second London edition, which amount to two 

 thirds of the whole, are taken nearly verbatim from the pub- 

 lications of Cavalio. 



The compiler of this work, while sitting with his pen in 

 one hand and his author in the other, appears never to have 

 indulged for a moment the illiberal suspicion that his author 

 might be in the wrong. The consequence is, that when- 

 ever his originals erred, the error is faithfully transcribed in- 

 into his abridgement. The number of these errors multi- 

 plied in his own hands, from the want of suflicient care to 

 shape and adjust materials, detached from their original 

 connexions, reducad in their dimensions, and sometimes 

 brought together from heterogeneous sources, — in such a 

 manner as to form parts of a connected and harmonious 

 whole. — Nor is the praise of judicious selection much bet- 

 ter deserved, than that of freedom from error. Proposi- 

 tions and scholia of little interest or importance compared 

 with others which might have taken their place, often occur : 

 complex and unsatisfactory demonstrations are admitted 

 where those of superior clearness and elegance were attain- 

 able : and while one chapter of an original author is pared 

 down to meagerness itself, another is left in a state of 

 redundancy. Even in those parts of the work to which no 

 objection can be made on the score either of accuracy or 

 importance, occur abrupt transitions in the subject or man'- 



