﻿482 Mr. F. L. 0. "Wadsworth on a New Method of 



a and/', where the two peaks would be in the same direction. 

 That this is not the case seems to us to render it practically 

 certain that it does not exist at all*. In other words, that 

 if the molecular currents are dve to a spinning motion of ionic 

 charges, this motion is not inseparably connected with a spinning 

 of the molecules themselves. 



LVIL A New Method of Magnetizing and Astaticizing 

 Galvanometer-Needles. By F. L. 0. Wadsworth f. 



[Plate XIII.] 



A GREAT deal of attention has been devoted by many 

 eminent physicists to the improvement of the galvano- 

 meter, and it has in consequence been brought to perhaps 

 as high a degree of delicacy and excellence as any of our 

 standard physical instruments. It is vain to hope for any 

 great advance in sensitiveness in existing types, but there will 

 always be a steady improvement in details and methods of 

 construction. 



One of the first essentials in securing a maximum degree 

 of sensitiveness in a galvanometer of the Thomson type is to 

 secure the maximum intensity of magnetization in the mag- 

 netic system. The maximum attainable will depend on three 

 factors : — first, on the form of the individual magnets and 

 their arrangement with reference to each other ; second, on 

 the quality of the steel used in making the magnets, and the 

 method of hardening and tempering the same ; and third, on 

 the method of magnetization. I have found that the intensity 

 of magnetization, and hence the sensitiveness of the galvano- 

 meter, depends on this last factor to a greater degree than has 

 usually been supposed, and that by using the method which 

 will presently be described the sensitiveness of a given gal- 

 vanometer may be doubled and in some cases more than 

 quadrupled. This results not so much from an improvement 

 in the magnetizing process per se as from the method of 

 application. 



The usual method of making the astatic system of the 

 Thomson galvanometer is to build up each member of the 

 system from a number of individual bar-magnets, each of 

 which is hardened and magnetized as strongly as possible 

 between the poles of a powerful electromagnet, either during 



* The only way out of this conclusion is to suppose that the peak has 

 been neutralized by some effect which we have overlooked, and which 

 does not change its sign with the direction of the heat-flow. But this is 

 unlikely. 



t Communicated by the Author, 



