38 Mechanical Philosophy. 



struction and motion o( pendulums, are neither few 

 nor unimportant. For the purpose of counteract- 

 ing the effects produced in the dimensions of the 

 pendulum, by heat and cold, from which disorder 

 and error necessarily arise, the contrivances of in- 

 genious men have been numerous and successful. 

 For the purpose, also, of regulating the curve in 

 which this body shall move, various devices and 

 calculations have been adopted. The principal of 

 these improvements are, the Mercurial Pendulum^ 

 invented by George Graham; the Gridiron Pen- 

 dulum; that formed with a rod of baked and var- 

 nished ivood; the contrivances, by means of a ^ei"/- 

 ble rod, and other apparatus, to make the pendu- 

 lum move in the curve of a cycloid; to say nothing 

 of many other ingenious inventions to regulate the 

 motions and to extend the ap{)lication of this im- 

 portant instrument. 



In that part of philosophy which relates to the 

 structure and motion of machines, many great 

 minds have been employed, in the course of the 

 last age, and not without making some advances 

 in this department of science.^ — -M. Amontons, 

 of the Royal Academy of Sciences at Paris, about 

 the beginning of the century, very successfully de- 

 veloped some of the general laws of machinery. 

 After him Mr. Emmerson, of Great-Britain, a 

 distinguished mathematician, investigated and sys^ 

 tematized this subject, with still more practical 

 care and accuracy. In 1735 the celebrated Eu^ 

 LER undertook to give a general and systematic 

 view of machines, in order to found a complete 

 theory, immediately conducive to the improvement 

 of mechanics. In 1743 he published the first 

 part of his theory, containing many new dynamical 

 theorems of great importance.' He afterwards 



c Comment. Petrofolitanu torn, i, 



