G.— ENGINEERING. 171 
of some of the chrome-nickel steels combined with their ductility 1s 
extraordinary, and is due not only to the composition of the metal, but 
to the results which have been obtained by patient scientific investiga- 
tions relating to their heat-treatment. Taking one other example, one 
may quote the use of high chrome steel—for the early investigations 
into which we owe so much to Brearley, and for its later developments 
to Hatfield also—tfor the valves of aeronautical engines, subjected as they 
are to high temperatures. At one time it looked as if the advantages 
which follow high compression and its resultant high temperatures 
might be lost owing to the inability of ordinary steels to resist this heat, 
but the employment of 13 per cent. chrome steel allowed work in this 
direction to be continued. Not only the aeroplane but the motor-car 
is, as has previously been said, the result of the work done on alloy 
steels. 
It is not only with steels that we have been benefited so much from 
research. ‘The case is as marked with light alloys, which have alu- 
minium as a base. The latter itself is the result of investigation along 
scientific lines, and in aeronautical work particularly much has been 
done towards giving a metal both light and strong by the work of Walter 
Rosenhain, F. C. Lea, and others. 
Tt may be said that all I have dealt with up to the present has been 
the result of special investigation, and that ‘ ordered knowledge’ is not 
of assistance to an everyday engineer such as myself. I may perhaps 
be forgiven if I refer to some personal work where the collection of that 
knowledge, with the assistance of my colleagues, especially I. Archbutt 
and H. A. Treadgold, has been of great assistance to that large transport 
institution, the Midland Railway, with which we were so long asso- 
ciated. I have dealt briefly with the subject in a general way in a paper 
Tread a little while ago before the Institution of Locomotive Engineers, * 
but would like to speak of it in more detail and in view of the fresh 
information that is now available. I would first speak of the results 
obtained with solid locomotive crank-axles. Here we have a large mass 
of metal which in the rough state weighs about 40 ewt. It is forged 
from the ingot into a block about 25 in. by 18 in. in section, and this 
is then worked down at the two ends and in the middle to about 11 in. 
in diameter, the pieces of the original section of the block remaining 
being the throws, which are twisted to an angle of 90° to each other. 
A block about 14 in. thick is slotted out of each web, and from these 
the tests to which the crank is subjected are taken. Sometimes a crank 
has to be taken out of service owing to the journal wearing down below 
a diameter at which it is judged safe for it to run, but more often 
flaws ave developed, which, however, are progressive, and with ordinary 
examination can be detected before any risk is taken in running. A 
crank-axle is an expensive portion of a locomotive, and its replacement 
is not only costly but takes a considerable amount of time, as the driving. 
wheels have to be removed and replaced. These considerations have 
led us to give a good deal of attention to this piece of mechanism 
on what we believe to be scientific lines. Careful note has been taken 
not only of the mechanical tests made on the portion removed from the 
4 Inst. of Loco, Hngineers, vol, 12, 1921. 
