584 ) 



of a more dirocl coinpni-isoii w c collccl ilio values of A for pressvircs 

 diiferiiiii- each tiiiic 100 adii. in aiiotlioi- (able. 



We SCO llial llie (litlrrcncos arc the same. All the values of h a( 

 200° are 8 imils less llinu (lie ('(irrespfuidiiiu' \alnes al 0° and at 

 JOO , because die \aliie of h,, al 200 is 7 unils less. Hut llie eoiirse 

 is always Jusl llie same. And as at a ii,i\eii \alne of yy we always 

 find iiicri'dsiiKi \aliies of /• at iiiereasiiig- temperalui'C, so the value 

 of A,, UMist of eoui'sc always deei'ease. 



From llie aboxe lollo\vs also, lliat we may deieniiiue A,, immedialely, 

 e.g'. adding' 52 mills to the \alues of A found a( 500 aim., or 32 

 units to Ihal al 400 aim., ele. 



On the preceding reasoning we may base the following short 

 calculali(m. 



At j).-^ — />! =: 100 the inilial value of h^ — Ji.^ amounis lo circa 10 

 cï 11; we ha\e therefore: 



y 10,5X10-^ 



^ 2R 100 



Therefoi'e 



}>,, — h^ -=, V^yf =10 •*' \/(h2lRT =10-3 l/()",21 X 0.0004 (1 -f afj, 



or 



h,, — />„ = 10 G 1/21 X lOMl + «0- 

 So we have al 0" 10"(^,— A„) = 458 (found 454). 

 At 100" we find 1 ()''(/>,,--/> J = V^ 21X^0^X1^7=535 (f(uuid 531). 

 At 200° we find l()''(A,y— Aj == ^'^21XJö'X^'^324=()03(foundG04). 



