the Heat-conductivity of Stone, 



265 



September 25, 1876. — Experiments on the stone ball of 6*9 

 centims. radius. 



The galvanometer-scale having been calibrated, it was found 

 that a deflection of one division on the scale to the right from 

 the zero indicated that the junction at the centre of the ball 

 was cooler than that in the compensating-bath by 0*022 C. 

 when the temperatures of the junctions was about 23° C. The 

 ball was then kept at 70° C. until the whole was at the same 

 temperature. The hot water was then suddenly removed and 

 a rapid stream of cold water at a temperature of 17° C. allowed 

 to flow over the ball, as described in § III. 





Observed 









Value of 







tempera- 



(thI vayin- 



GullVEillO" 



Tempe- 



galvanome- 



True tem- 



Time, in 

 minutes. 



ture of 

 compen- 

 sating 

 bath. 



\A CbX. V CU-L\J 



meter- 

 reading. 



meter 

 zero. 



rature of 



stream of 



water. 



ter deflec- 

 tion in de- 

 grees Cen- 

 tigrade. 



perature of 



centre of 



ball. 





o 







o 



o 



o 







69-8 C. 



5R 







68 C. 



-01 c. 



69-7 C. 



2 



70 



32 R 







23 



-07 



69-3 



n 



69-2 



2L 









+0 



69-2 



3 



68-7 



8L 









+0-2 



68-9 



3* 



68-6 



9L 









+0-2 



68-8 



4 



68-7 



2L 







2l' 







687 



H 



68-6 



3R 









-01 



68-5 



5 



68-4 



2R 



2L 









68 4 



H 



68-5 



14R 



2L 



20 : 8 



-0-3 



68-3 



6 



68-1 



21 R 



2L 





-0-5 



676 



H 



672 



6R 









-01 



67-1 



n 



66 



13R 







20 : 8 



-03 



65-7 



8 



66-2 



48R 









-01 



65-2 



H 



66 



75 R 









-1-6 



64-4 



H 



58-1 



160 L 







20 : 5 



+3-5 



61-6 



10 



58-6 



95 L 









+2-0 



60-6 



10± 



58-8 



43 L 









4-10 



59-8 



11 



59-2 



20 R 



1L 





-0-5 



587 



HI 



59-3 



70 R 









-1-5 



578 



12 



58 



70 R 









-1-5 



56-5 



12* 



56 



32 R 







20 : 3 



-0-7 



55-3 



]<T 



55-2 



50 R 









-11 



541 



I3f 



53-2 



22 R 









-05 



52-7 



14 



518 



10R 







20 : 3 



-0-2 



51-6 



14* 



514 



29 R 









-0-6 



50-8 



15 



49 8 



5R 









-01 



49-7 



15* 



49-4 



34 R 







20 : 3 



-0-5 



489 



16 



48 



15R 









-0-3 



477 



16* 



47-1 



20 R 









-0-4 



46-7 



17 



457 



5R 







20 : 3 



-01 



45-6 



m 



44 



29 L 









+0-6 



44-6 



18 



43-9 

















43-9 



18* 



43-3 



15R 







20-3 



-03 



43 



19 



41-6 



21 L 









+0-5 



421 



19* 



411 



5L 







20 : 3 



+0-1 



41-2 



20" 



40-2 



5L 









+0-1 



40-3 



21 



39-6 



33 R 









-07 



38-9 



