224 IMPROVEMENTS I'M CHRONOMETERS* 



tides of mattf^r, either both within a body, or one t^'itliin 

 and the other witliout, tend toward each other by the same 

 law of force, and therefore the cause of that tendency, that 

 is, in our present consideration, the variation of the density 

 of the fluid, must in both cases be regulated by the same 

 which would law. If we were to admit the position advanced by Dytis- 

 ton in a contra- *^"^' '"^ would involve Newton in a contradiction, and instead 

 diction. of affecting the truth of my proposition, would further tend 



to confirm it. To change the law of density immediately y 

 would be to substitute two fluids instead of one, such a 

 change necessarily implying a change of the fluid; for what 

 better criterion have we of different fluids, than that their 

 constitutions are regulated by different laws? To defend 

 liis objections, Dytiscns makes an assumption totally incon- 

 sistent with Newton's hypothesis. 



I do not think it necessary to make any farther remark^ 

 on the observations of Dytiscus, and I must make an apo- 

 logy to mathematicians for having said so much; but I was 

 induced to do it upon this consideration, that they might 

 liot mislead those who are ignorant of the subjeet. 



I am. Sir, 



Your obliged humble servant, 

 Cambridge, 9 JunCy 1808. S. VINCE. 



XIII. 



Certain Improvements in Chronometers, by Daniel Derino 

 Mathew, Caius College, Cambridge. In a Letter from 

 the Author^ 



SIR, 



HP 



1 H 



Chronometers JL HE degree of accuracy, to which chronometers have 

 crJaUrTm- b^^» brought within these few years, may appear to be the 

 jroved. utmost to which, in a machine so complicated, human art 



could extend ; but as navigation has derived great advan- 

 tages from improvements made in them, I have been 

 tempted to make some alterations in their construction, the 



superiority 



