president's address. 9 



and power of cutting metal. In otbei^ words, it holds the carbon more 

 tenaciously in the hardened state, and hence tungsten steel tools, even 

 when red hot, can cut ordinary mild steel. It has revolutionised the 

 design of machine tools and has increased the output on heavy munition 

 work by 100 per cent., and in ordinary engineering by 50 per cent. 



The alloys of steel and manganese with which the name of Sir Robert 

 Hadfield is associated have proved of utility in immensely increasing 

 the durability of railway and tramway points and crossings, and for 

 the hard teeth of machinery for the crushing of stone and other materials, 

 and, in fact, for any purposes where great hardness and strength are 

 essential. 



Investigation of Gaseous Explosions. — Brief reference must also 

 be made — and it will be gi'atifying to do so — to the important work 

 of one of the Committees of the British Association appointed in 1908, 

 under the chairmanship of the late Sir William Preece, for the investi- 

 gation of gaseous explosions, with special reference to temperature. 

 The investigations of the Committee are contained in seven yearly 

 reports up to 1914. Of the very important work of the Committee I 

 wish to refer to one investigation in particular, which has proved to 

 be a guiding star to the designers and manufacturers of internal com- 

 bustion engines in this country. The members of the Committee more 

 directly associated with this particular investigation were Sir Dugald 

 Clerk, Professor Callendar, and the late Pi'ofessor Bertram Hopkinson. 



The investigation showed that the intensity of the heat radiated 

 by the incandescent gases to the walls of the cylinder of a gas engine 

 increases with the size of the cylinder, the actual rate of this increase 

 being approximately proportional to the square root of the depth of 

 the radiating incandescent gas ; the intensity was also shown to increase 

 rapidly with the richness of the gas. It suffices now to say that the 

 heat in a large cylinder with a rich explosive mixture is so intense 

 that the metal eventually cracks. The investigation shows why this 

 occurs, and by doing so has saved enormous sums to the makers of 

 gas and oil engines in this countiy, and has led them to avoid Hie 

 large cylinder, so common in Germany before the war, in favour of 

 a multiplicity of smaller cylinders. 



Science and the War. 

 In coming to this section of my Address I am reminded that in 

 the course of his Presidential Address to Section G, in 1858, Lord 

 Eosse said : ' Another object of the Mechanical Section of the Associa- 

 tion has been effected — the importance of engineering science in the 

 service of the State has been brought more prominently forward. There 

 seems, however, something still wanting. Science may yet do more 

 for the Navy and Army if more called upon. ' 



