224 Dr. C. R. A. Wright on the Number of 



molecules upon which this magnetism depends, and illustrated 

 it by a woodcut*. Still more fully are these phenomena and 

 others related to them treated in the volumes of PoggendorfF's 

 Annalen from 1858 to 1862, quoted in my workj. 



In the year 1866 (Pogg. Ann. cxxix. p. 616) I showed that 

 when a current is directed through an iron wire extended in 

 the axis of an induction-coil and the wire is twisted or un- 

 twisted, induced currents are produced in the coil; further, 

 that similar induction currents are produced by twisting or 

 untwisting the wire after having interrupted the current pass- 

 ing through it ; also that analogous induction currents pass 

 through the wire itself when, after the passage of the current, 

 its ends are joined to a galvanometer and it is twisted or un- 

 twisted. 



These results in each case follow directly from my former 

 direct observations on the magnetization of an iron wire by 

 twisting or untwisting during or after the passage of a current. 



It is not difficult to vary the experiments, as, in fact, Prof. 

 Hughes has done. My purpose being to establish the prin- 

 ciples of these phenomena, I considered it best to study them 

 under the simplest possible conditions. 



It gives me great pleasure to find that the experiments of 

 so distinguished a philosopher as Prof. Hughes, which either 

 agree completely with my own or have been made with some 

 variations of method, confirm the results which I obtained 

 about twenty years ago, and that, in describing molecular 

 magnetism as a singular form of magnetism, he has indepen- 

 dently come to the same conclusions as those published by me 

 in the years 1858-1862, when enunciating the theory of the 

 relations between magnetism and mechanical changes of mag- 

 netic bodies. 

 Leipzig, August 6, 1881. 



XXVIII. On Mr. R. Shida's Note published in the Philoso- 

 phical Magazine for August 1881. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



THE contents of Mr. Shida's last note, and the addendum 

 thereto by Sir William Thomson, render it imperative 

 upon me unwillingly to trouble you again upon this subject — 

 I trust, for the last time. In Mr. Shida's original papers 

 (Brit. Assoc. Reports, 1880, and Phil. Mag. Dec. 1880) he 

 stated that, in the course of his electrostatic valuations of v, 



* Oalvanismus, 1st ed. ; ii. p. 453 ; 2nd ed., iii. (1) p. 573. 



t Pogg. Ann. ciii. p. 563 (1858) ; cvi. p. 161 (1859) ; cxvii. p. 203 

 (1862) ; and Monatsber. d. Berlin. Acad. 1860, 29 Nov. ; also in the Annales 

 de Chimie et de Physique, the Archives de Geneve, Silliman's Journal, &c. 



