418 C. Barus — Torsional Magnetostriction, etc. 



tion is an increment of rigidity in all paramagnetic metals ; 

 whereas the permanent effect of a transverse or a circular field 

 is relatively inappreciable so far as rigidity is concerned. At 

 least its certain detection would have to be left to researches 

 of a higher order of refinement than was reached in the 

 method pursued. This conclusion is at variance with much of 

 the earlier work on the subject, but I do not see how the 

 step for step march toward this result which the above simple 

 experiments contain can be evaded. 



Finally, the suggestions of the model (figures 1 and 2) are in 

 keeping with the data found. Cf. § 2. 



The quantity which I have here considered is the permanent 

 effect of magnetization or rigidity, i. e., that which persists 

 after making and breaking the field many times. Besides this 

 there is a very striking temporary effect of marked relative 

 value, in the interest of which the present experiments have 

 largely been made. The relation of this temporary effect to 

 viscosity will be considered in the paper soon to appear. 



Brown University, Providence, It. I. 



