PEIRCE. — MAGNETIC BEHAVIOR OF HARDENED CAST IRON. 363 



B curve to the hard one. While it would be difficult to explain the 

 exact meaning of these curves in terms of the permeabilities of the 

 iron, the differences are striking. 



Figure 4. 



It appears from the observations of Ewing upon Vicker's Tool Steel 

 that in the case of the specimen he used the value of I was still rising, 

 and at a fairly rapid rate, when H grew to be as great as 14,000. The 

 same tendency, it will be noticed, is shown very clearly in the two kinds 

 of »toei which I have studied. These were chosen as being perhaps 

 the best annealed brands of fine tool steel to be had in the market. 



