414 Mr. G. K. Winter on the Maximum Magnetizing 



the present time, but getting more and more irregular; and I 

 need hardly say how well this agrees, with the observed facts 

 both of the present disposition of mountain-chains^ and the strike 

 of the oldset known Laurentian rocks. 



Summary. — Mountain-chains may be divided into two classes — 

 the one characterized by folds and contortions associated with 

 metamorphic rocks (such as the Alps), the other by slightly 

 inclined beds associated with volcanic rocks (such as the Andes) . 

 The former class of mountains are owing to heavy masses of clay 

 and sand having caused subsidence and contortion, and then 

 having been subsequently elevated by the superposition of a thick 

 bed of limestone. The latter class are owing to the depressions 

 caused by deposition necessitating an equal uprising in other 

 places. Many intermediate varieties also occur, which are owing 

 partly to one cause and partly to the other. Such is a sketch 

 of the Herschel-Babbage theory ; to elaborate it in detail would 

 require a far greater knowledge of the geology of the world than 

 I possess. But although it may be shown that it is not in itself 

 sufficient to account for all observed phenomena, yet I hope that 

 some good will arise to science by sifting out by its means 

 from our heterogeneous mass of facts all those that it will ex- 

 plain, and thus limiting the residual phenomena in a way that 

 will be most likely to lead ultimately to a complete solution of 

 the question. 



L. On the Relation which the internal Resistance of the Battery 

 and the Conductivity of the Wire bear to the maximum Magne- 

 tizing Force of an Electromagnet Coil. By G. K. Winter, 

 F.R.A.S.y Telegraph Engineer j Madras Railway^. 



IN Poggendorff^s Annalen for November 1865, and in the 

 Philosophical Magazine for December of the same year, is 

 published an investigation by Dr. Menz/.er on the relation of 

 the weight of a magnetizing spiral to the magnetizing force. 

 In this paper the author shows that, cat eris paribus, the mag- 

 netizing powers of two coils, arranged to give the maximum 

 force with a given battery, are as the square roots of their re- 

 spective weights. In this investigation the average length of 

 a convolution is supposed to be constant; and as the iron rod 

 to be magnetized is, I presume, supposed to remain the same, 

 the length of the helix will also be a constant. It is difficult 

 to conceive, under these circumstances, how the law can be ap- 

 plied, except within narrow limits — since, the size of the coil 

 being constant, the weight of the wire must be a constant too, 



* Communicated by the Author. 



