Determination of the Thermal Conductivity 



of Marble. 



Kenjirö Yamagawa, Ph. B. 



Professor of Physics, Imperial University. 



If .1 solid sphere at a given temperature be immersed into a 

 water-batli at another temperature, and the water be stirred vigorously, 

 we may assume that, after a short tiine, the surface of the sphere is at 

 the same temperature as the bath, provided that the substance 

 constituting the sphere be a \evy poor conductor of heat, such as 

 stone, Avood, &c. In fact, most determinations of the conductivities 

 of these substances ai'e based on this assumption. Tlu' method used 

 in the experiments to be described in the present paper also assumes 

 this fact. A stone sphere of a convenient size is immersed into a 

 liath of a constant temperature for a certain time, and is then suddenly 

 taken out, and dipped into another bath at another constant tempera- 

 ture f )r the same length of time ; then again into the first bath, and 

 so forth. After a certain iiuiidjer of cycles, the temperature of any 

 point in the interi<ir of the sphere will Ije subject to a steady oscillation 

 about a definite mean. Ihe determination of the thermal conducti- 

 \iiy of the substance may be effected by observing the temperature- 

 \ aviation at any such point, say, for simplicity the centre. 



Through the kindness of Mr. Nakano of the Physical Laboratory 

 of the Kökwa Daigaku (Engineering College), the sLone-spheres used 

 by Professors Ayrton and Perry in their determination of the heat- 

 conductivity of stone were placed at my disposal. After working 



