A Trestle cf B O D I S. Chap. 9- 



why there is required a weight of water in double Geometri- 

 call proportion, to make a pipe run twice as fart as it did, or to 

 have twice as much water run out in the fame time?Unto which 

 I anfwer out of the fame ground as before : That bccaufc in 

 running twice as faft,there goeth out double water in every part 

 of time; and again, every part of water gocth a double fpacc in 

 the fame part of time; that is to fay, becaufc double the celerity 

 is drawn into double the water, and double the water into dou- 

 ble the celerity ; therefore. the prefent effe is to the former ef- 

 fcft, as the effect or quadrate of a double line drawn into it Celt, 

 is to the effect or quadrate of half the faid line dravrn into ic 

 fclr". And confequently the caufe of the latter effect ( which is 

 the w eight then _) muft be to the caulc of the former effect ( that 

 is, to the former weight) in the fame proportion; namely, as the 

 quadrate of a double line, is to the quadrate of half that line. 

 And fo you fee the reafon of what he by experience findeth to 

 be true. Though I doubt not but when he ftiall fet out the Trea- 

 dle which he hath made of this fubjcft, the Reader will have 

 better fatisfaction. 



In the mean while, an experience which Galileo delivereth: 

 \\ill confirm this dodtrine. He faith,that to make the fimc pen- 

 dant go twice as faft as icdid, or to make every undulation of ic 

 in half the time icdid; you mud make the line at which ic hang- 

 eth, double in Geometricall proportion to the line at which ic 

 hanged before. Whence it followeth, that the circle by which ic 

 goech is likewifc m double Geometricall proportion. And this 

 being certain , that celerity to celerity hath the proportion of 

 force, which weight hath f to weight; it is evident, that as in one 

 cafe there muft be weight in Geometricall proportion; fo in the 

 other cafe, where onely celerity rnaketh the variance, thccele- 

 riry muft be in double Gemetricall proportion, according as 

 Galileo findeth it by experience. 



But to return to our, main intent,there is to be further noted, 

 that if the fubjcct ftrucken be of a proportionate ceffibility, ic 

 feemeth to dull and deaden the ftroke : whereas, if the thing 

 ftrucken be hard, the ftroke lecmeth to lofe no force, but to 

 work a greater effe5r. Though indeed the truth be, that in both 

 cafes the effects are equall ; but divcrfc according to the natures 

 of the things that arc ftruckcn;for no force that once is in nature 

 can be loft, but muft have its adequate effect one way or other. 



Let 



