1874.] Spectroscopic Observations of the Sun. 247 



between the wires themselves and not between the currents, repulsion in- 

 stead of attraction must be due to difference of direction of structure pro- 

 duced by difference of direction of the currents. 



Although the Amperean theory has rendered immense service to mag- 

 netic science, and agrees admirably with all the phenomena of electro- 

 magnetic attraction, repulsion, and motion, it is in some respects defec- 

 tive; it assumes that magnetism is due to innumerable little electric 

 currents continually circulating in one uniform direction round the mo- 

 lecules of the iron ; but there is no known .instance of electric currents 

 being maintained without the consumption 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) to definite directions of molecular 

 structure, such as is shown by the phenomena of electro-torsion 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 electro-torsional state after the currents or other causes producing 

 them have ceased. 



According so this view, a magnet, like a spring, is not a source of 

 power, but only an arrangement for storing it up, the power being re- 

 tained 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-resistance. 



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

 site direction of structure in a body will impart to it the capacity of being 

 acted upon by a magnet ; and any substance, ferruginous 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 pro- 

 perty, whilst freely suspended, of pointing north and south by the direc- 

 tive influence of terrestrial magnetism, and one of stannite (oxide of tin) 

 points east and west under the same conditions. 



IV. " Spectroscopic Observations of the Sun." By J. NORMAN 

 LOCKYER, F.R.S., and Gr. M. SEABROKE, F.R.A.S. Received 

 February 2, 1874. 



(Abstract.) 



This paper consisted of the observations made of the sun's chromo- 

 sphere and of the prominences for the period 1st September, 1872, to 

 31st December, 1873. Details are given of the modes of observation 

 adopted. 



