ON THE MEREDIAK. ij 



^fid tBis may be called the meafure at the temperate 50.^ 

 Now tahave the exceTs of the old chain above the ilandard 



one by thefe experiments, it was obferved that on the 21 il, 



the_yZ(27i^^r^/ chain exceeded the bra fs meafure by , . 0,1 \^(^' 

 And the me of uring one h J , . , . i 0,32797' 



The difference is therefore the excefs of the meafuring 



flandard chain "« - - - - . 0,21190 



0n the 23d, the standard chain eirceeded the brafs meafore 



at the temperature 65.7^ - - - - 0,1134^ 



And the meafuring; chain exceeded at the temperature o£ 



66.2 Q^ by - » - - - - 0,327a E 



BilFerence is the escefs of the meafuring chain above the 



ilandard one - - - - - » 0,21357 



Erom which dedu61:o°,55-f, 00742, or - » 0,00408 



The difference will be the excefsat 65°,7 temperature - o,20Qz<q 

 Excefs on the 2 1 fl: - — - - «• 0,21199^ 



Mean of the fe two in inches- *- •■ ». 0,2107.1, 



In making thefe allowances for the change of temperature after the 

 brafs meafure was laid off, it is prefumed, that in fo fhort a time the 

 brick wall, which was fhaded by the tents, could not have fufferec|,^ 

 any change, efpecially as the alteration ia temperature was fo triflino-. 



From comparing what the chain had lengthened by thefe lad exoeri- 

 ments, with what it had lengthened by thofe made Sit Be U{irj, it ap- 

 pears that in that interval of time, or nineteen months, it had,increafe(l 

 0,04608 inches, or 00.384 feet, fo that if we fuppofe thefincreafe to 

 be regular, it would have encreafed from before the meafurement a£- 



F. 



