12 Scientific Proceedings , Royal Dublin Society. 



For assistance in making some of the observations I am indebted to 

 Mr. F. O'Carroll, a Fourth-year Experimental Science Teacher, in training 

 in this College. 



Note. — With respect to the internal friction of materials, I would draw 

 attention to a very interesting paper on " The Internal Friction of Nickel in 

 a Variable Magnetic Field," by Prof. Ernesto Drago of the E. University of 

 Catania, Italy. (R Accad. dei Lincei, vol. xxiv, serie 5 a , 2° sem., fac. 1°, Roma, 

 Luedio, 1915.) 



