﻿412 Messrs. K. Scheel and W. Heuse on the 



theories as those described in the following paper *. Further 

 discussion of this point is, therefore, postponed until the 

 account of that work is complete. 



Leeds University, 

 Nov. 18, 1911. 



Note added Feb. 10. 



Mr. Bishop has recently (Phys. Zeits. xii. p. 11-18, 1911) 

 published an account of a very complete experimental test of 

 the accuracy of Townsend's theory. His formula differs 

 slightly from that of Townsend in the nature of the relation 

 between a and the quantities N and V, but it appears to me 

 open to the same criticism as has been made in this paper, 

 in that it does not reduce to the right form when I is less 

 than b. The absence of a divergence between observed and 

 calculated values is probably due to the fact that throughout 

 his experiments I was much greater than b. 



XXXVII. Concerning the Thermal Kxjpan&ion of Mercury, 

 Remarks on a Paper by Callendar and Moss. By Kakl 

 SCHEEL and WlLHELM H.EUSE |. 



l e A BOUT a year ago Callendar and Moss % published the 

 jTJl results of a comprehensive investigation of the thermal 

 expansion of mercury, in which they used the method of 

 balanced hydrostatic tubes. The authors themselves state 

 that there is a considerable difference between their results 

 and those obtained by Cbappuis§ in the Bureau international 

 des Poids et Mesures. They raise the objection against the 

 measurements of Chappuis, who used the dilatometer method, 

 that it is not allowable to calculate the cubical expansion 

 of a body by multiplying its linear expansion measured 

 in only one direction by 3, since the hereby assumed 

 isotropy of the body is not certain. 



One might consider perhaps that this objection is correct, 

 if, as Callendar and Moss have done, only the results of 

 Chappuis for the expansion of mercury are discussed. In 

 reality, however, a proper opinion concerning the reliability 



* To be published in the April number. 



t Communicated by the Authors from the Physikaliseh-Technischen 

 Reichsanstalt. 



X Hugh L. Callendar and Herbert Moss, Phil. Trans. (A) 211. pp. 1-32 

 (1911). 



§ P. Chappuis, Trav. et Mem. du Bureau international des Folds et 

 Mesures, xiii. C, 31 pp., 1903 (1907). 



