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LI. — 01^ A MODEL ILLUSTRATING SOME PEOPERTIES OE 

 THE ETHEE. By GEORGE ERANCIS FITZGERALD, M.A., 

 E.T.C.D., E.R.S. 



[Eead, January 19, 1885.] 



The model I have constructed consists of a series of wheels, rota- 

 ting on axes fixed perpendicularly in a plane board, and connected 

 together by indiarubber bands. The axes are fixed at the inter- 

 sections of two systems of perpendicular lines, and each wheel is 

 connected with each of its four neighbours by an indiarubber band. 

 Thus all the wheels can rotate without any consequent straining of 

 the system if they all rotate at the same rate. If, however, some 

 of the wheels be rotated through a different angle from others, the 

 indiarubber bands will be strained. 



If it is desired to represent a region in which conducting mat- 

 ter exists, it will be represented by removing the bands from a set 

 of wheels. Suppose the bands are removed from the regions a and 

 h, and from the connecting line ah, we can represent the charging 

 of these regions with opposite electricities by introducing some 

 mechanism, by means of which the wheels on opposite sides of the 

 line ah can be rotated in opposite directions. And now I desire 

 to explain that I do not intend the model to illustrate at all the 

 connexion between the ether and the matter, and indeed think it 

 one of the advantages to be derived from studying this model that 

 it so distinctly emphasizes the distinction between the phenomena, 

 depending on the general properties of the ether by itself, and 

 those depending on its connexion with matter. For instance, 

 from this very case we are considering, we get impressed upon us 

 that it is by means of matter only that we can get a hold on the 

 ether so as to strain it. As I am not careful to illustrate the con- 

 nexion between matter and ether, any rough method of turning 

 the wheels so as to create the proper strain, will do well enough, as 

 it is not the method of producing but the nature of the strain pro- 

 duced that I wish to study. Having once rotated these wheels, 

 we may replace the bands along the line a h, and we have the 

 state of the ether between two oppositely electrified bodies repre- 



