562 Further Observations on Slip-Bands -in Metallic Fraetures. 



Fig. 2 (Plate 14). (The diagram is a replica of one originally used by 

 Professor Ewing and the present author to illustrate their explanation 

 of the character of slip-bands, see paper referred to above.) The 

 change of direction of the steps on passing from one crystal to another, 

 as indicated on the diagram, is readily observed on the actual sections. 

 The method above described of supporting the surface of a metal 

 specimen by means of an electrolytic deposit so us to render possible 

 the production of accurate transverse sections, is capable of application 

 to a number of questions. The author is engaged in applying it to one 

 of these, viz., the study of fractures produced in various ways. The 

 difficulty of obtaining satisfactory sections of fractures has hitherto stood 

 in the way of systematic investigation of the path taken by fractures; 

 the photomicrograph, Fig. 4 (Plate 14), shows how the present method 

 overcomes this difficulty ; it represents a section through a " fibrous " 

 fracture of a piece of very mild steel, under a magnification of 

 90 diameters. As compared with the sections of slip-bands, the details 

 of such a fracture are very large, but even under the highest magnifi- 

 cation the sharpness of the boundary is maintained, and it is even 

 possible to follow the path of the fracture among the lamellae of the 

 pearlite in this steel. The investigation of flaws, of the edges and 

 cuts of cutting tools are further examples of questions which can be 

 investigated by the aid of the method here described. 



Specimens of iron and steel for the experiments here described have 

 been very kindly supplied to the author by Messrs. Joseph Sankey, of 

 Bilston, and Messrs. Cammell, Laird and Co., Limited, of Sheffield. The 

 cost of some of the apparatus and a portion of the expense of this 

 investigation have been defrayed out of a grant from the Government 

 Grant Committee of the Royal Society, and the author is also indebted 

 in this connection to the Council of the Iron and Steel Institute for the 

 award of an Andrew Carnegie Research Scholarship. 



