Sir jfoseph Petavel 189 



matter. A diamond is pressed into it, and then the 

 resultant marks are examined under a powerful micro- 

 scope. 



The Metallurgy Department at Teddington is also very- 

 interested in this problem of ' fatigue ' of metals, but the 

 means they use are furnaces, microscopes, and chemical 

 analyses. 



There you can see metals heated to the highest attain- 

 able temperature. They do this with what they call 

 their high frequency valve furnace, which will raise the 

 temperature of a metal until it reaches the staggering 

 figure of one thousand six hundred degrees Centigrade. 

 The valves, much like ordinary wireless valves, are about 

 two feet long, and cost seventy-five pounds each ! 



More amazing still is the fact that this intense heat is 

 generated in the body of the metal itself, in such a way 

 that the outside of the furnace remains cool enough to 

 be touched. 



In another department the problems of the motorist 

 are dealt with. Every motorist knows the danger of 

 skidding on wet and greasy surfaces, but how many know 

 that at Teddington scientists are every day seeking to 

 solve the problem ? They have there a skidding machine 

 — a motor-cycle and side-car, with a wheel specially made 

 for skidding. Instead of having the dials and gadgets 

 dear to the heart of the youthful motor-cyclist, this 

 machine is decorated with apparatus which records all 

 that happens when it is deliberately skidded over a pre- 

 pared surface. 



Another road problem in which these scientists are 

 interested is the effect of wheels on road-surfaces, and 

 another is the search for the ideal road-making material. 



A lorry which can be fitted with various kinds of wheels 

 is used in tracking down the type of wheel that is respon- 

 sible for most road damage. But the most remarkable 

 machine is the road-surface tester, a weird contraption 



