Intelligence and Miscellaneous Articles, 395 



instance of electric currents being maintained without the consump- 

 tion of power, and in magnets there is no source of power ; electric 

 currents also generate heat, but a magnet is not a heated body. 



If, however, we substitute the view that the phenomena of 

 attraction and repulsion of magnets are due, not to continuously 

 circulating electric currents, but (as in electric wires )Jto definite 

 directions of molecular structure, such as is shown by the pheno- 

 mena of electrotorsion to really exist in them, the theory becomes 

 more perfect. It would also agree with the fact that iron and steel 

 have the power of retaining both magnetism and the electrotor- 

 sional state after the currents or other causes producing them have 

 ceased. 



According to this view, a magnet, like a spring, is not a source 

 of power, but only an arrangement for storing it up, the power 

 being retained by some internal disposition of its particles acting 

 like a "ratchet" and termed "coercive power." The fact that a 

 magnet becomes warm when its variations of magnetism are great 

 and rapidly repeated, does not contradict this view, because we 

 know it has then, like any other conductor of electricity, electric 

 currents induced in it, and these develop heat by conduction-resist- 

 ance. 



According also to this view, any method which will produce the 

 requisite direction of structure in a body will impart to it the capa- 

 city of being acted upon by a magnet ; and any substance, ferrugi- 

 nous or not, which possesses that structure has that capacity ; and, 

 in accordance with this, we find that a crystal of cyanite (a silicate of 

 alumina) possesses the property, whilst freely suspended, of point- 

 ing north and south by the directive influence of terrestrial magne- 

 tism, and one of stannite (oxide of tin) points east and west under 

 the same conditions. 



LV. Intelligence and Miscellaneous Articles. 



ON THE TEMPERATURE OF THE SUN. BY J. VIOLLE. 



I. "OUESUINGr my researches on the effective temperature of the 

 -*- sun as I have previously defined it (see the Philosophical Ma- 

 gazine for August and September, pp. 158 and 233), I effected a 

 number of measurements in an enclosure at a high temperature. 

 These experiments appeared to me to present a special interest in 

 consequence of the affirmation, first put forth by Mr. "Waterston, and 

 afterwards supported by Father Secchi, that the excess of tempera- 

 ture received by a thermometer under the action of the sun is inde- 

 pendent of the temperature of the enclosure in which the thermo- 

 meter is placed — whence this consequence, that the 200° or 250° 

 which we have varied the temperature of the enceinte " without 

 observing the least difference, either in the amount of the excess or 

 in the time employed in attaining it," are only an insignificant frac- 

 tion of the temperature of the sun. It is, however, easy to demon- 



