744 



NATURE 



[August 12, 1920 



fuzes were the subject of many investigations. As 

 an example may be mentioned the hammer of the 

 No. 106 fuze. This was Hable to failure at a 

 time of great output until the causes of difficulty 

 were ascertained and sound methods of manufac- 

 ture established. The introduction of a simple 

 form of heat-treatment rendered possible the use 

 of a rapid and economical stamping method which 

 greatly assisted supply. 



An investigation carried out upon brass sm.all 

 arm cartridge cases gave very complete informa- 

 tion connecting the behaviour of the case in the 

 rifle with its properties, and especially with its 

 hardness. The hardness is chiefly dependent on 

 the degree of cold-work received in the final draw- 

 ing operation, and manufacturers were assisted by 

 information as to the requisite hardness at dif- 

 ferent parts of the case and the dimensions of the 

 necessarv tools for producing it. The measure- 



FlG. 5. — View in microscope room. 



ments to ensure exact control of the hardness have 

 been made possible by the use of a small machine 

 designed in the Research Department shortly 

 before the war for the determination of the hard- 

 ness of very thin specimens. In this machine, 

 which has proved useful in many unexpected 

 ways, the Brinell test may be made on samples 

 one-hundredth of an inch or even less in thickness, 

 with balls as small as o-8 mm. in diameter. 



A thorough investigation of the phenomenon 

 of " season-cracking " in brass and its prevention 

 by low-temperature annealing has had a useful 

 application in the removal of internal stress from 

 cartridge cases. 



Methods of casting brass ingots have been much 

 improved. The long, narrow moulds formerly 

 employed for ingots to be used in the manufac- 

 ture of rod were productive of troublesome defects 

 in the finished article. 



The occurrence of the "extrusion defect," a 



NO. 2650, VOL. 105] 



central core of unsound material, in brass rod 

 used for fuzes led to an extended study of the 

 extrusion process, in which the flow of the hot 

 brass is liable to form internal defects in a re- 

 markable and characteristic way. A method of 

 controlling the plastic flow to produce entirely 

 sound rod has been devised. 



The necessities of the war demanded that first 

 consideration should be given to the solution of 

 immediate practical problems. The use of sub- 

 stitutes and alternative methods of manufacture 

 when supplies ran short, the easing of specifica- 

 tions to increase output with safety, the adapta- 

 tion and introduction of inspection tests to meet 

 changing conditions, the examination of enemy 

 material, the tracing of causes of failure and the 

 discovery and application of remedies, provided a 

 large field for investigation. Work on the funda- 

 mental properties of metals and alloys, which is 

 so necessary if research in ap- 

 plied metallurgy is to continue 

 to be fruitful, was, however, 

 continued throughout the war, 

 and is now being further 

 developed. 



Radiological Branch. 



In the beginning of 1916 the 

 question of the penetration of 

 metals by X-rays was first con- 

 sidered by the Research Depart- 

 ment. After experiments with 

 various types of apparatus under 

 different conditions, it was 

 found possible to penetrate a 

 block of steel half an inch in 

 thickness and show internal 

 flaws. The Department at once 

 realised the possibilities in- 

 volved in this new use of X-rays 

 as applied to Service require- 

 ments, and took steps with the 

 best apparatus available to 

 evolve a technique for applying 

 the new method as widely as possible, not only 

 for detecting flaws in steel, but also for the exam- 

 ination of various articles, such as unknown 

 enemy ammunition, where for reasons of safety 

 it was desirable to know the internal construction 

 before breaking down. X-rays were also applied 

 to many Service stores for the purpose of indi- 

 cating defective assembly, and for discovering 

 faults such as blow-holes and internal flaws in 

 metals. 



As research progressed it became apparent that 

 in order to obtain the best results the whole 

 subject of radiology needed careful study so that 

 its methods might be modified and adapted to this 

 new use. More powerful tubes and high-power 

 electrical machinery were essential, and the photo- 

 graphic side of the subject required special treat- 

 ment. A general scheme of research on the sub- 

 ject of radiology as applied to the examination of 

 Service materials was consequently undertaken, 



