Intelligence and Miscellaneous Articles, 725 



At a depth of 18 feet were echinids and barnacles. Two other 

 galleries were explored, and in these, as in the lower gallery, the 

 walls are pitted to a height of 28 feet above sea-level. The author 

 concludes that the cave existed at first as a fissure, to which the 

 sea later obtained access through a large entrance for a long 

 period ; and during this period the Kock was elevated some 42 feet. 

 The cave was closed to the sea at a period geologically recent ; and 

 the breccia and sand-slopes at this point on the eastern side of the 

 Rock, which are 150 feet wide and reach to a height of 200- 

 300 feet above sea-level, date from a still more receut period. 



XCIII. Intelligence and Miscellaneous Articles. 



ON THE INFLUENCE OF MAGNETIC FIELD ON THERMAL 

 CONDUCTIVITY. 



To the Editors of the Philosophiccd Magazine. 



Gentlemen,— Bologna, Nov. 4, 1903. 



T WOULD ask permission to say a few words in connexion with 

 -^ the interesting memoir published by Mr. Vincent J. Blyth in 

 the number of May 1903 of your periodical (p. 529), which begins 

 with the following words : — 



" In a circuit composed of bismuth and another metal the thermo- 

 electric E.M.F. is altered, if the bismuth be placed in a magnetic 

 field. This alteration was observed by Leduc and by Righi, while 

 using such a circuit as a means of measuring the difference of 

 temperature between two points of a heat-conveying bar of 

 bismuth." 



jN'ow I beg leave to state that in my experiments on the thermal 

 conductivity of bismuth in a magnetic field {Mem. delta B. Accad. 

 dei Lincei, 4^ serie, t. iv., p. 433, II iV. Cimento, 3^ serie, t. xxiv. 

 p. 5), I made use of thermoelectric elements in which bismuth did 

 not enter at all, and which permitted me to measure independently 

 the temperatures in three equidistant points of the bismuth bar. 



It was therefore impossible that thermoelectric modifications 

 produced in the bismuth by the magnetic field could have any 

 influence on my results. 



I shall be most thankful to you if you will publish these lines in 

 your periodical. 



Tours truly, 



August Eighi, 

 0. Prof, of Physics in the 

 Universitv, Boloofna. 



