<*ct. |u.] DISSERTATION SECOND. 103 



Now, such perpetual motion, he adds, is impossible, and 

 therefore the chain, as here supposed, with the arch hang- 

 ing below, does not move. But the force of the arch be- 

 low draws down the ends of the chain equally, because the 

 arch is divided in the middle or lowest point into two parts 

 similar and equal. Take away these two equal forces, and 

 the remaining forces will also be equal, that is, the tenden- 

 cy of (he chain to descend along the inclined plane, and 

 the opposite tendency of the part hanging perpendicularly 

 down, are equal, or are in equilibria with one another- 

 Such is the reasoning of Stevinus, which, whether per- 

 fectly satisfactory or not, must be acknowledged to be 

 extremely ingenious, and highly deserving of attention, as 

 having furnished the first solution of a problem, by which 

 the progress of mechanical science had been long arrested. 

 The first appearance of his solution is said to have had 

 the date of 1585; but his works, as we now see them, 

 were collected after his death, by his countryman Al- 

 bert Girard, and published at Ley den in 1634. > Some 

 discoveries of Stevinus in hydrostaticks will be hereafter 

 mentioned. 



The person who comes next in the history of mecha- 

 nicks made a great revolution in the physical sciences. 

 Galileo was born at Pisa in the year 1561. He early ap- 

 plied himself to the study of mathematicks and natural 

 philosophy ; and it is from the period of his discoveries 

 that we are to date the joint application of experimental 



1 The edition of Albert Girard is entitled Oeuvres Mathemati- 

 ques de Stcvins, in folio. See Livre I. De la Staliquc, theorem 

 11. Stevinus also wrote a treatise on navigation, which was 

 published in Flemish in 1586, and was afterwards honoured with 

 a translation into Latin, by Grotius. The merit of Stevinus has 

 been particularly noticed by La Grange. Mccaninue Analytiqne, 

 Tom. I. Sect. 1. 5 5. 



