68 Mr. H. H. Poole on Thermal Conductivity and Specific 



The distance between the P.D. junctions on the central 

 wire was 10*0 cm. ; the diameter of the outer groove was 

 2'61 cm. and that of the inner 0*725 cm. ; so, taking C for 

 granite as 0'53, we find that with the same notation as 

 before, 



W 



K= 4-875 xlO- 3 x 



where W = W-0712a. 



A specimen day's observations are shown in Table II. 



Table II. (Granite). 



T. 



E. 



V. 



A. 



W. 



■ E i. 



e . 



E 2 . 



9. 



4P. 



a. 





9"5 A.M. 



400 



(turne 



d on) 



















11-47 „ 



340 









31205 



15-6 



3301 



240 









1*4 P.M. 



2-0 „ 



800 



1-3692 

 1-3686 



5-834 

 5-836 



7-982 

 7-981 



3064-5 

 3051 



16-7 



17-3 



3259 

 3254-5 



237-5 

 237 



61-52 

 61-50 



-0-0052 





334 „ 



650 









5612 



18-5 



5822 



400 









4-30 „ 





1-4321 



5-414 



7-755 



5548 



19-4 



5779-5 



398 



63-57 







6-8 „ 





1-4309 



5-418 



7-752 



5491 



20-1 



5728 



395 



63 53 



■4-0-0059 



63-53 



! 





640 „ 





1-4306 



5-416 



7-748 



5492-5 



20-2 



5731 



395 





Here : — 



T = Time at which reading of E x was made. 



R, = Setting of regulating wattmeter in arbitrary units made after 

 the corresponding readings had been taken. No entry is 

 made when E, was not changed. 



Y = P.D. between the leads iu volts measured on the potentio- 

 meter. 



A = Central current in amperes measured on the potentiometer. 



W = VA = Power developed in the central wire between P.D. 

 leads. 



E x = E.M.F. of the single couple in microvolts. 



6 = Temperature of the mercury key forming the cold junction 

 of this couple. • 



E 2 = Calculated E.M.F. of this couple with its cold junction at 

 0°C, correction having been made for e. 



6 X = Temperature corresponding to E read from a curve. As tho 

 distance of the single junction from the centre was about 

 0*88 cm. which was greater than Vr r„ a small correction 

 depending on A was added in reading off so as to obtain, 

 the true mean temperature. 



