374 Dr. Ure’s new experimental researches 
If we denominate the absolute elongation of the heated 
metallic rod from 32 0 to i22°,io, then its elongation from 122 0 
to 212 0 ; from 21 2° to 302° ; from 302° to 392 0 ; from 392 0 to 
482°, was in each successive interval of 90° F, as nearly as pos- 
sible 10 also. The slight irregularities, incident to all delicate 
experimental investigations, being often in opposite directions, 
in different repetitions of the same experiment; or those which 
manifested themselves in the ascending or elongating range, 
were neutralized, so to speak, by others of an inverse nature, 
which appeared in the cooling retrocession. Here, the 
movements of the liquid mercury and of the solid rod by 
heat proceeded, pari passu, through a very great extent of tem- 
perature. Let us now recollect that these 5 increments, 
which on our thermometer are equivalent to 5 x 90° = 450° ; 
and which altogether produce five times the elongation that 
the first interval occasions, constitute, on Mr. Dalton’s scale, 
only 350°. If we call the first interval given by this philoso- 
pher 1.00, then the four succeeding intervals contain a range 
of temperature on his scheme, of only two and a half times 
the first ; and therefore only two and a half times additional 
elongation should have been produced, instead of four times, 
as found by experiment. “ Since for all practical purposes 
uniform increments of bulk, or expansions of solids by heat, 
correspond to uniform increments of this power then each 
of our old successive intervals of 90° may, for all practical 
purposes, be held to correspond to equal increments of 
temperature. 
Mr. Dalton’s intervals from 32 0 to 482° Fahr. are as 
before given, 102°.4; 77°.6; 55 0 .7; 50°.5 = 350°.!. 
Now, if we call the first quantity 1 .00, it will produce on a 
