ADMIT OF CHANGES IN THEIR TEMPKRATURE. 



71 



exactly as the fquares, and (heir folic! contents as the cubes of 

 their diameters. From this, and what has been already pre- 

 mifed, it will follow, that in bodies of different (izes, fimilarly 

 fhaped, and of the fame fubftance, the capacity for heat wilt 

 be as the cubes, and the mutability of temperature as the 

 fquares of their diameters or tides ; and that, therefore, the 

 degree of the tendency of thofe bodies to maintain an equality 

 of temperature, may be eftimated as their folid contents minus 

 the relatire value of their furfaces : Bodies whofe fhapes are 

 diflimilar, will in feme degree be fubject to the fame rule; 

 but it is not material to the prefent fubject to take them farther 

 into confideration. 



The following table of the proportion of four cubes in the Table of the ra- 

 above refpects, whofe fides are reciprocally as 1, 2, 3, and 4, F ' dlty of 



will exemplify what has been above afierted, and fhew how 

 greatly the retention of temperature of bodies is increafed bv 

 adding to their bulk. 



and cooling. 



A 

 B 

 C 

 D 



Side. 



Surface. 



Change 

 of Heat as 



Bulk. 



Capacity 

 for Hea't. 



Retention 

 of Heat 

 eftimated. 



Feet. 

 I 

 2 

 3 

 4 



Square Feet. 



6 : 1 



24 : 4 



.54 : 9 



96 : 16 



1 



4 



9 



16 



Cubic Ft. 



1 



8 

 27 

 64 



1 



8 



27 



64 



1 



4 

 18 



48 



From thefe conn" derations the following inferences may be Inferences, 

 drawn : \fi, That the greater the bulk of any body, the lefs 

 will be its mutability of temperature in proportion, and of 

 courfe the lefs will it alter its degree of expanfion : 2d, That 

 a large globe in the firft place, or a cylinder, whofe height 

 was equal to its diameter, in the next place, or in the third 

 place a large cube, would have its dimenfions very little 

 changed by the fluctuations of atmofpherical temperature. 



To apply thefe principles to the regulation of horological Application of 

 movements may appear difficult, as the firft idea that would ^ o e c f ^ fa<as ta 

 occur is, that it would be neceflary to put thofe large bodies 

 in motion for this purpofe; but this is by no means needful, 

 and it may be effectually performed by confiructing and fixing 

 up a pendulum in fuch a manner, that its variations in length 

 fhall be corrected by, and depend on, thofe of the large body. 



There 



