546 



Mr. Seibei Konno on the Variation of 



vertical electric furnace. To avoid the convection-current 

 in the furnace as much as possible, the free space in the 

 furnace is loosely filled with asbestos fibre. The furnace 

 consists of a porcelain tube 5*5 cm. wide and 45 cm. long, 

 a nichrome wire being uniformly wound round it and the 

 exterior thickly covered with asbestos paper. The whole 

 arrangement is shown in fig. 3. 



The terminals of four sets of the thermocouples ab, ca, 

 ef, a'b' are dipped in the eight mercury cups on a paraffin 

 block, as shown in fig. 4. Two copper wires connected to 



Fiff. 4. 



I 













a 







*>. 





e 





 



6 



9 



6 



9 





, «- 



f 



o — 



b 



a 



b' 





d 



a wall-galvanometer (made by Leed & Northrup), is led 

 into a glass tube H and fixed by paraffin, the two terminals 

 pp protruding from the lower end of the tube. The ter- 

 minals can be put in any pair of the mercury cups by 

 holding the glass tube in the hand. In this way the differ- 

 ence in the temperatures between two junctions in any pair 

 of the four thermocouples can successively be observed with 

 the single galvanometer. 



§ 3. Metliod of Observation. 



Let Q be the quantity of heat generated per unit of time 

 in the heating-coil, and let q, t, and K be the quantities of 

 heat flowing per unit of time, the temperature differences 

 per unit of length and the thermal conductivities respec- 

 tively, subscripts 1, 2, 3 and 4 referring to the iron pieces 

 A, B, C, and J) respectively. When the stationary state is 

 attained, the lateral loss of heat is always very small in 

 comparison with #, and we have 



q = K 1 $ l t 1 , q 2 = K 2 S 2 t 2 , tf3=K 3^3*3, ^ 4 = K 4 S^ 4 , 



where S is the sectional area of the iron pieces. 

 A, B, D are made of the same material, we have 



K 1== K 2 =K 4 = K', and K 3 = K. 



Since 



