20 Mr. \V. Sturgeon on the Thermo-magnetism of 



major part of those piles are absolutely set in that position, 

 and not a single crystalline film has its plane determined at 

 right angles to the axis of the metal. Hence it is that the 

 edges of the greatest part of the bundles of lamina? are pre- 

 sentied to view at every transverse fracture, and may be com- 

 pared to tall narrow bundles of thin metallic leaves, or slips 

 of paper, placed round a central nucleus, with one of their 

 narrow ends presented to the centre and the other towards the 

 surface of the cylinder; which position, together with others 

 which some of those bundles assume, give to them the ap- 

 pearance of radii, with various degrees of splendour. Fig. 14. 

 will assist in giving an idea of the general disposition of the 

 strata of crystals in a transverse section of an uniformly dense 

 cylinder of antimony. 



70. If the sharp edge of a hammer be applied in the direc- 

 tion of the axis, the cylinder may be completely dissected 

 from its surface to its centre; or the crystalline layers may 

 be peeled off" one after another with very great accuracy, as 

 far as the dissection is required to be carried on. When a 

 cylinder of antimony is thus disrobed, it presents an exceed- 

 ingly beautiful appearance: the refulgent facets of its crystals 

 are exposed to view, which stud its surface as if it were 

 decked in a most brilliant coat of mail ; whilst the multitude 

 of spangles which those facets display are now seen to be dis- 

 posed in the crystalline arrangement already described. 



71. Assuming, then, that the general crystalline arrange- 

 ment is that of concentric laminae, two hypotheses may per- 

 haps present themselves for an explanation of the thermo- 

 magnetic phaenoniena elicited in an uniform cylindrical bar 

 of antimony, one of which, it appears to me, will ultimately 

 be found to be the true theory. 



72. First, then, it may be supposed that the opposite faces 

 of each metallic film are in different states of electricity, or at 

 least that they have different thermo-magnetic qualities. If 

 it could be satisfactorily proved that this were the case, their 

 concentric arrangement would reconcile the pha?nomena to 

 all those which are displayed by the juxta-position of any 

 pair or series of pairs of dissimilar metallic plates, and each 

 bundle of films would become an electric column. In that 

 case the thermo-magnetic character of the inner surface of 

 each film would be to its outer surface as bismuth is to anti- 

 mony ; for the current in a pair of those metals flows through 

 the point of heat from the former to the latter ; and the rest 

 of the circuit answers no other purpose than that of a con- 

 ductor. When the point of heat is close to the edge of a 

 transverse fracture of a cylinder of antimony, two, or a very 



few 



