20 Messrs. J. Tyndall and H. Knoblauch on the 



can possibly cause the rotation of the entire mass round an 

 axis, and the taking up of a fixed position by the mass, with 

 regard to surrounding objects, appears to us insurmountable. 

 We have endeavoured to illustrate the matter, to our own 

 minds, by the action of a piece of leather brought near a red- 

 hot coal. The leather will be affected and motion caused, 

 without the intervention of either attraction or repulsion, in 

 the present sense of these terms; but this motion exhibits 

 itself in an alteration of shape > which is not at all the case with 

 the crystal. Even if the direct attraction or repulsion of the 

 poles be rejected, we do not see how the expressed relation 

 between the magnecrystallic axis and the magnetic resultant 

 is possible, without including the idea of lateral attraction 

 between these lines, and consequently of the mass associated 

 with the former. In the case of flat poles, the magnetic re- 

 sultant is a straight line from pole to pole across the magnetic 

 field. Let us suppose, at any given moment, this line and 

 the magnecrystallic axis of a properly suspended crystal to 

 cross each other at an oblique angle ; let the crystal be for- 

 gotten for a moment, and the attention fixed on those two 

 lines. Let us suppose the former line fixed, and the latter 

 free to rotate, the point of intersection being regarded as a 

 kind of pivot round which it can turn. On the evolution of 

 the magnetic force, the magnecrystallic axis will turn and set 

 itself alongside the magnetic resultant. The matter may be 

 rendered very clear by taking a pair of scissors, partly open, 

 in the hand, holding one side fast, and then closing them. 

 The two lines close in a manner exactly similar; and all that 

 is required to make the illustration perfect, is to suppose this 

 power of closing suddenly developed in the scissors themselves. 

 How should we name a power resident in the scissors and 

 capable of thus drawing the blades together? It may be 

 called a 'tendency,' or an c endeavour,' but the word attraction 

 seems to be as suitable as either. 



The symmetry of crystalline arrangement is annihilated by 

 reducing the mass to powder. "That force among the par- 

 ticles which makes them cohere in regular order" is here in- 

 effective. The magnecrystallic force, in short, is reduced to 

 nothing, but we have the same results. If, then, the principle 

 of elective polarity, the mere modification of magnetism or 

 diamagnetism by mechanical arrangement, be sufficient to 

 explain the entire series of crystalline phaenomena in the mag- 

 netic field, why assume the existence of this new force, the 

 very concept ion of which is attended with so many difficulties* ? 



* " Perhaps," says Mr. Faraday, in a short note referring to ' the strange 

 and striking character ' of this force, " these points may find their explica- 

 tion hereafter in the action of contiguous particles." 



