August 12, 1920] 



NATURi 



745 



and this included the construction, in the Depart- 

 ment, of special apparatus and high-tension elec- 

 •rical machinery; research was also undertaken 



'II such associated subjects as the detection of 



ieble radiation and the measurement of its in- 



tnsity. 



Certain progress has been made, with the result 

 that X-rays are being used to a much greater 

 extent as research proceeds. X-ray examination 

 of welds is the only method by which their sound- 

 ness can be demonstrated, and it is now possible 

 to penetrate more than 2^ in. of steel to show 

 internal flaws. Fig. 6 shows part of one installa- 

 tion in the Research Department for the examina- 

 tion of materials. 



Proof and Experimental Branch. 



All guns are tested to a pressure in excess of 

 their working pressures, and the ballistics of all 

 lots of propellants are ascertained, by firing into 

 sand butts. Carriages, recuperators, and many 

 small stores are also similarly proved before 

 acceptance. 



Velocities are measured by means of Boulange 

 chronographs, and pressures by means of copper 

 crushers in piston gauges. Flat-headed shot are 

 used, to keep the penetration into the sand butts 

 as low as possible. 



Experimental firing, which principally consists 

 in the determination of the weights of propellant 

 necessary to give specified ballistics under various 

 conditions, is also undertaken, and for this pur- 

 pose the proof butts staff work in collaboration 

 with the internal ballistic branch, by which the 

 preliminary calculations are made. 



Considerable expansion of personnel and 

 maUriel was necessary during the war to cope 

 with the vast amount of proof and experiments. 

 At the armistice the staff had increased to nearly 

 ten times its pre-war figure, and included a 

 number of women, who were most efficiently per- 

 forming their trying duties on the firing batteries. 



Internal Ballistic Branch. 



Starting with a staff of two in the early part of 

 the war, the branch numbered at the armistice 

 more than twenty members, who dealt with all 

 problems relating to the internal ballistics of pro- 

 pellants and the internal design of guns for all 

 the Services. Newer and more powerful apparatus 

 has been devised for determining the burning 

 characteristics of explosives, and a great improve- 

 ment has taken place in methods of analysing 

 data. This is especially noticeable as regards the 

 ballistic design of ordnance. The old system of 

 calculation in use prior to the war was based on 

 trial and error, and involved a series of laborious 

 and lengthy operations. It had the added dis- 

 advantage of restricting the calculator to working 

 out this result with one definite set of initial con- 

 ditions only, and consequently no certain predic- 

 tions could be made as to whether the best com- 

 bination of charge weight, propellant size, cham- 

 ber capacity, etc., had been employed. 



It was thus frequently found that the finished 

 erun was not suitable for the original purpose in 

 NO. 2650, VOL. 105] 



I view. Research into the thermodynamical pro- 

 j perties of propellants led to the construction of 

 a more accurate theory on which to base design, 

 and, apart from the economy effected in the labour 

 of calculation, it became possible to select with 

 considerable accuracy the best and most econo- 

 ; mical combination for any ballistic requirements. 

 I Also by an application of the calculus of varia- 

 tions the calculator is now enabled to predict with 

 j considerable accuracy the probable deviation in 

 j the ballistics from round to round, a valuable 

 I criterion of the practical utility of a design. 

 j The application of this new theory effected con- 

 ! siderable changes in design. For example, it was 

 found that large reductions could be effected in 

 the chamber capacities of several guns, with 



Fig. 6. — Portion of radiological laboratory. 



corresponding reductions in the charge weights, 

 without affecting the ballistics. This modification 

 had the result of materially increasing the life of 

 the guns, and the reduction in charge weight 

 effected an appreciable economy in the financial 

 cost of each round, a serious consideration in 

 view of the magnitude of the scale on which 

 operations were conducted. 



Since the armistice the ballistic branch has been 

 to a large extent occupied in digesting and inter- 

 preting the data amassed during the war, the 

 results being published in the form of R.D. 

 Reports. 



A programme has been drawn up for future 

 research, and good progress is being made in all 

 branches of the science and its applications. 



