102 



PRINCIPAL FORBES ON AN EXPERIMENTAL INQUIRY INTO 



mentally determined, and both in an almost evanescent state (as is the case in the 

 extreme portion of the curve of statical temperature and of the statical curve 

 of cooling), the quotient may be sensibly in error. To this I add, that in Case I. 

 the length of the bar was certainly not quite sufficient to allow the conducted 

 heat to be entirely spent by dissipation. Consequently there is, as it were, a 

 slight congestion of heat towards the extremity — very slight indeed, but still 

 sufficient to give to the subtangent there a too large value, and consequently to 

 the decrement of the primary curve of temperature too small a one. Hence the 



Z 

 ratio dv_ is somewhat too great, both in consequence of the numerator being too 

 dx 



large and the denominator too small. But how little any such ambiguity can 



effect the general evaluation of the flux of heat in the succeeding lines of the Table, 



either in the case of this or of the two succeeding experiments, will be seen by 



noticing the minuteness of the areas representing the flux which correspond to 



the extreme portions of the curves. They are so small, that an error amounting 



to one-half their amount, would hardly affect by ^oth or 4-J^th part the measure 



of the conductivity in the middle and more important part of the Tables. 



TABLE IX. — Case I. I^-inch Iron Bar, Naked. Calculation of Area of Statical 

 Curve of Cooling (F), and of the Conductivity at Different Temperatures. 



Limits of Abscissas. 



Limits of Ordinates. 



M=Sub- 

 tangent.* 



Area 

 M(y'-y). 



Total 



Area 



F. 



dv 



~Tx 



Conduc- 

 tivity, 

 F. 

 dv 



Corre- 

 sponding 

 Actual 

 Temp. 

 Cent. 











X. 



%' . 



y- 



y'- 











~Tx 



(»+13). 



Ft. Inch. 



Ft. Inch. 



O 









j 









00 



VI. 



o- 



0008 



1-662 



0-0133 









VI. 



IV. 



•008 



•043 



1189 



•0416 00549 



3 34f 



•0164 



17 



IV. 



III. 



•043 



•114 



1-026 



•0728 



•1277 



8-15-j- 



0157 



22 



III. 



II. 



•114 



•342 



•9104 



•2075 



•3352 



24-47 



•0137 



37 



II. 



I. 6 



•342 



•620 



•8403 



•2336 



•5688 



■ 43-7 



•0130 



53 



I. 6 



I. 



•62 



1-245 



•7175 



•4484 



1-0172 



85-35 



•0119 



85 



I. 



9 



1-245 



1-80 



•6777 



•3762 



1-3934 



1230 



•0113 



110 



9 



„ 7-5 



1-80 



220 



•6233 



•2493 



1-6427 



1488 



•0110 



127 



„ 7-5 



„ 6 



2-20 



270 



•6100 



•3050 



1-9477 



181-0 



•0107 



147 



„ 6 



,, 5 



2-70 



301 



•7669 



•2378 



2-1855 



206-8 



•0105 



163 



» 5 



„ 4 



301 



3-32 



•8515 



•2640 



2-4495 



237-1 



0103 



182 



„ 4 



„ 3 



3-32- 



364 



•9047 



•2895 



2-7390 



272-4 



0100 



203 



„ 3 



„ 2 



3 64 



3-97 



•960 



•3168 



3-0558J 



313-7 



•0097 +. 



228 



„ 2 



„ 1 



3-97 



432 



•986 



•3451 



3-4009 + 



362-5 



•0093 + 



256 



„ 1 



>, 



4-32 



4-71 



•965 



•3764 



3-7773 + 



4200 



•0090+ 



288 



(1) 



(2) 



(3) 



(4) 



(5) 



(6) 



(7) 



(8) 



(9) 



(10) 



i 



* Fr 



"im flip "Po 



rmnln O' 



1343 x X ~ X ' 









! 





Jill \. ll\-j J. \J 



A 111 I 1 1 it \J 



log y - los 



\y 







t 



1 



From curve ; the 



rest fron 



1 equatioi 



1. + Mor 



3 or less 1 



mcertain. 



p 



