HEAT, 



substance, a, the expansion of which is 

 to be tried, is laid upon the rest, 

 touching an immoveable screw at one 

 end, and the moveable index at the 

 other ; as soon as the heat of the spirit- 

 lamp b is applied, the substance, if it is 

 a very expansible one, will begin to ex- 

 pand, and its comparative degree of 

 expansibility will be shown by the dis- 

 tance to which the index c moves along 

 the graduated part of the instrument d. 



In comparing different substances to- 

 gether with this instrument, it will be 

 necessary to make all the rods of 

 the same size, and to apply the heat 

 of the lamp the same length of time 

 to each. 



The following TABLE of the " linear 

 dilatation of solids by heat," is taken 

 from Dr. lire's Dictionary of Chemistry, 

 and is probably the most correct ex- 

 tant. 



Dimensions which a bar takes at 212 whose length at 

 1.000000. 



Glass tube Smeaton 



Do Roy 



Do De Luc's mean 



Do Dulong and Petit 



Do Lavoisier and Laplace . 



Plate glass Do. do. 



Do. crown glass Do. do. 



Do. do. Do. do. 



Do. do. Do. do. 



Do. rod Roy 



Deal Do. as glass 



Platina Borda 



Do Dulong and Petit 



Do Troughton 



Do. and glass Berthoud 



Palladium Wollaston 



Antimony Smeaton 



Cast-iron prism Roy 



Cast iron Lavoisier by Dr. Young. 



Steel Troughton 



Steel rod Roy 



Blistered steel Phil. Trans. 1795, 428 . 



Do Smeaton 



Steel not tempered Lavoisier and Laplace , 



Do. do. do. Do. do. 



Do. tempered yellow Do. do. 



Do. do. do Do. do. 



Do. at a higher heat Do. do. 



Steel Troughton 



Hard steel , , , . Smeaton , , . 



32 is 



I*' 

 .00083333 



.00077615 

 .00082800 TTT? 

 .00086130 TiW 



.00081166 TT52 



.000890890TT42 

 .00087572 TIT?, 

 .00089760 

 .00091751 

 .00080787 



.00085655 

 .00088420 

 .00099180 

 .00110000 

 .00100000 

 .00108300 

 .00110910 

 .00111111 

 .00118990 

 .00114470 

 .00112500 

 .00115000 

 .00107875 

 .00107956 

 .00136900 

 .00138600 

 .00123956 

 .00118980 

 .00122500? 



sir 



8*7 



