Intelligence and Miscellaneous Articles. 329 



3. " Note on a Reptilian Tibia and Humerus (probably of Hylceo- 

 sauras), from the Wealden Formation in the Isle of Wight/' By 

 J. W. Hulke, Esq., F.R.S., F.G.S. 



In this communication the author describes two saurian limb- 

 bones, remarkable for the great expansion of their articular ends, 

 and the shortness and smallness of their shaft. The features of the 

 tibia are more like those of the tibia of Hylceosaurixs than of any 

 other Dinosaur. This resemblance, and the suitability of the humerus 

 to the very massive articular end of the Hylaeosaurian scapula, dis- 

 pose the author to refer the bones to this Saurian. 



XXXVII. Intelligence and Miscellaneous Articles. 



ON THE MAGNETIZING-FUNCTION OF TEMPERED STEEL. 

 BY E. BOUTY. 



r FHE magnetic moment of a magnetized needle may always be 

 regarded as the product of two factors, of which the one 

 expresses the quantity of magnetism contained in the needle (or, 

 if preferred, the power of each pole), while the other factor is 

 equal to the distance of the poles. By the advice of M. Jamin I 

 applied myself to determine these two distinct elements separately, 

 and to study apart the variation of each of them when the condi- 

 tions of magnetization are changed. The following is the principle 

 of the method employed. 



It is easy to verify that the magnetic moments y of a series of 

 needles of different lengths ,v, magnetized under the same condi- 

 tions, can be represented by a formula such as 



y=m(x—d), (1) 



provided that their lengths exceed a certain limit I. In all these 

 needles the quantity of magnetism is constant and equal to m, and 

 the distance of the poles from the extremities is also constant and 



equal to — . If we break these needles and take from their middle 



parts various fragments of lengths exceeding another limit V<1, 

 their moments y' are represented by the formula 



y'=m(x'-l): (2) 



the quantity of magnetism is the same as in the mother needle ; 

 but the poles are nearer to the extremities, £ being always less than 

 d. These facts, almost evident a priori, have been carefully veri- 

 fied by experiment. 



Suppose now that m and d are to be determined for a given 

 needle. We first ascertain its magnetic moment y ; it is then re- 

 duced by the removal of a sufficient length from both ends, and the 

 new magnetic moment y determined. We know * that in rupture- 

 needles of the same diameter the quantity I is constant, whatever 

 the intensity of the magnetization ; its value, known beforehand, 

 is, for instance, 5-5 millims. in needles of 0*553 millim. diameter, 



* " Studies on Magnetism," III., Phil. Mag. March 18/5, pp. 188-191, 

 Phil. Mag. S. 4. Vol. 49. No. 325. April 1875. Z 



