FOR MEASURING THE EXPANSION OF SOLIDS. 
271 
rison have added from calculation their expansion from 62° to 212°, by reducing 
the former in the proportion of 180 : 150. 
Table VI. 
Length of Bar. From 32° to 212°. From 62° to 212°. Authorities. 
Platinum .00088420 X 6.5 = .005747300 = .004789416 Dulong & Petit. 
Iron . .00118203X6.5 = .007683195 = .006402662 Dulong & Petit. 
Copper .00171821X6.5 = .011168365 = .009306970 Dulong & Petit. 
Tin . .00217298X6.5 = .014124370 = .01 1770308 Lavoisier & Laplace. 
Zinc . .00294200X6.5 = .019123000 = .015935833 Smeaton. 
Lead . .00284836X6.5 = .018514340 = .015428616 Lavoisier & Laplace. 
Brass . .00193000x6.5 = .012545000 = .010454166 Smeaton. 
Gold . .00146606X6.5 = .009529390 = .007941158 Lavoisier & Laplace. 
Silver . .00190974x6.5 = .012413310 = .010344424 Lavoisier & Laplace. 
Upon deducting from the amount of these several absolute enpansions the 
apparent expansions in the black-lead register, we shall obtain the expansion 
of the latter from 62° to 212°, as derived from the several metals. The results 
are comprised in the following Table. 
Table VII. 
Expansion of 
Platinum . 
Expansion of the Metal Bars. 
. absolute .00478 
Black-lead Register. 
Difference from Mean. 
apparent .00276 
. =.00202 . 
. —.00032 
Iron . . . 
. absolute .00640 
apparent .00508 
. =.00132 . 
. -.00102 
Copper . . 
. absolute .00930 
apparent .00683 
. =.00247 . 
. +.00013 
Tin . . . 
. absolute .01177 
apparent .00814 
. =.00363 . 
. +.00129 
Zinc . . . 
. absolute .01593 
apparent .01454 
. =.00139 . 
. -.00095 
MDCCCXXX. 
2 N 
