386 On the CONTRACTION 



Unwilling to remain in uncertainty, and confidering it as a 

 point of much curiofity and intereft, I have endeavoured to in- 

 veftigate the fubjed; by experiments condu(fled in a totally dif- 

 ferent manner, equally calculated to exhibit the Angular truth, 

 but free from the objedions to which the others are liable. In 

 them, it was my objedl to provide, that neither the changes of 

 the adlual volume of the water, nor the alterations in the dimen- 

 fions of the inftrument, fliould have any influence whatever. 



I HA VE already taken occafion to ftate, that the purpofe of this 

 paper is to prove, by experiments on the principle now mention- 

 ed, that in the conftitution of water there really exifts the fuigu- 

 larity often noticed. 



I SHALL firfl ftate the plan of the experiments, and then detail 

 the particulars of the mofl remarkable of them. 



When any body is dilated, whether by heat or cold, it necef- 

 farily becomes lefs denfe, or fpecifically lighter ; and the oppofite 

 cffedls refult from contradlion. This is the circumftance, as eve- 

 ry one knows, which caufes various movements among the parti- 

 cles of fluids, when any inequality of temperature prevails in 

 tTie mafs ; hence thefe particles are little acquainted with a fl;ate 

 of reft. 



If a partial application or fubtradlion of heat produce an in- 

 eqviality of denfity in a mafs of fluid, the lighter parts rife to the 

 furface, or the denfer fall to the bottom. 



It readily occurred, that 1 might avail myfelf of thefe move- 

 ments, and upon ftatical principles determine the queftion in diC- 

 pute. 



I HAD only to examine attentively water, as it was heated or 

 cooled in a jar, and to obferve, by means of thermometers, what 

 fituation the warmer, and what the cooler parts of this fluid af- 

 feaed. 



If I ftiould find that ice-cold water, in acquiring temperature, 

 fliowed, in its whole progrefs, the warmer parts near the top, it 



would 



