G.—ENGINEERING 137 
influence on mechanical engineering progress, there was another influence 
which was destined to bring about revolutionary changes in the design 
and construction of machinery, in this country and, indeed, the world 
over. This was the gradual substitution of science, and the scientific 
method, for the ‘ rule-of-thumb’ procedure of the so-called ‘ practical 
man.’ The change in this regard has taken place almost entirely during 
the past fifty years. 
As Sir Alfred Ewing pointed out in his Presidential Address to this 
section a few years ago, there were in 1881 a few great leaders—a Kelvin 
or a Hopkinson—who possessed the right kind of basic understanding, 
who could turn to theory for guidance and had the engineer’s instinct to 
give it application. But most of the zealous workers of those days were 
groping in what was at best a half light, full of enterprise and enthusiasm 
and not much more. But the few great mentors to whom Sir Alfred 
Ewing referred were the pioneers who helped to bring about what I 
believe to have been a great material revolution in human affairs. For it 
was they, together with other leaders in the universities and elsewhere, 
who laboured at the development of engineering theory, and who first 
taught us to realise the illimitable benefits to be secured by the application 
of physical science to the whole range of engineering activity. When 
I look back over the period now under review I realise that the greatest 
lesson conveyed is that the advancement of engineering is in the last 
resort determined by the advancement of physical science. I would, 
indeed, go further, and say that my experience, specialised though it has 
been, has taught me that the whole structure of modern civilisation rests 
upon the progressive application of physical science to the ever expanding 
requirements of mankind. 
During the past half-century there has been a similarly phenomenal 
development in many other branches of mechanical engineering, notably 
those concerned with the naval and military services, radio-communica- 
tion, aviation, transport (including rail and road), etc. etc. Considerations 
of time make it impossible to deal adequately with these developments 
here, but, as we have already seen, it seems certain that at no previous time 
in the history of the world has mechanical development been so rapid. 
While the history of engineering development is a fascinating subject, 
we have to live in the present, at a time when economic considerations 
have become of vital importance in their bearing upon technical matters, 
so that no apology should be necessary for discussing very briefly the 
scientific methods of carrying out an engineering installation of to-day. 
Years ago any engineering firm of repute could obtain a considerable 
proportion of its work with no particular effort, sometimes even without 
the necessity of preparing a contract. Such times have gone by. There 
is severe competition for what seems often a somewhat limited amount of 
work, and sustained and intensive effort is necessary to secure the amount 
of business requisite to keep open one’s works. ‘The soil must be tilled 
diligently—sometimes, indeed, for years—before the crop is reaped. 
To achieve this end no effort must be spared. A prospective customer 
often requires much education as to the savings which will accrue from the 
substitution of new and modern plant for his obsolete machinery, and to 
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