-1859] WRITINGS OF JOSEPH HENRY. 107' 



The electro-magnetic phenomena appear to be due to the 

 action of the atoms of gross matter combined with that of 

 the ajtherial medium. 



We cannot here go into an exposition of the facts of 

 electricity and magnetism, but will merely point out one 

 inference from the hypothesis we have given, namely that 

 electricity is not in itself a primary source of motion or 

 mechanical energy, tending to produce change by a kind of 

 spontaneity, (as is frequently supposed,) but is the effect of 

 a disturbance and subsequent restoration of an equilibrium, 

 which disturbance has been produced by the application of 

 an extraneous force. This conclusion may also be arrived 

 at, without reference to the hypothesis, from the study of 

 the facts themselves, which clearly demonstrate that the 

 electrical equilibrium (whatever may be its nature) is never 

 disturbed by its own action, but the manifestation is always 

 the effect of the application of some other power, and is the 

 mechanical equivalent of such disturbing cause. 



Orystalline forms. — We will now consider the grouping of 

 the atoms which is intimately connected with the various 

 properties of different kinds of bodies. When the atoms of 

 gross matter are suffered to approach each other, without 

 disturbance or agitation, and from an aeriform or liquid 

 condition to gradually assume the solid form, they exhibit 

 beautiful geometrical figures, familiarly known under the 

 name of crystals. For example if a quantity of common 

 salt be dissolved in water and the liquid be suffered to 

 evaporate in a still place, beautiful crystals of a cubical form 

 will be found in the vessel; or if ordinary saltpetre be dis- 

 solved in warm water and suffered to cool, regular six-sided 

 crystals will be obtained. If these crystals be reduced to 

 an impalpable powder and again dissolved in hot water the 

 same result will again be produced, provided the liquid be 

 not in excess. 



The most interesting illustration of crystallography to 

 the meteorologist is that exhibited in snow and hoar frost. 

 These generally consist of stellar figures in one plane, with 

 rays and branches of rays, all making angles of 60° with 



