I have just mentioned a distinction between the industrial revolution and the scientific revolution. The distinction is not clear-edged, but it is a useful one, and I ought to try to define it now. By the industrial revolution, I mean the gradual use of machines, the employment of men and women in factories, the change in this country from a population mainly of agricultural labourers to a population mainly engaged in making things in factories and distributing them when they were made. That change, as I have said, crept on us unawares, untouched by academics, hated by Luddites, practical Luddites and intellectual ones. It is connected, so it seems to me, with many of the attitudes to science and aesthetics which have crystallised among us. One can date it roughly from the middle of the eighteenth century to the early twentieth. Out of it grew another change, closely related to the first, but far more deeply scientific, far quicker, and probably far more prodigious in its result. This change comes from the application of real science to industry, no longer hit and miss, no longer the ideas of odd ‘inventors’, but the real stuff.

Dating this second change is very largely a matter of taste. Some would prefer to go back to the first largescale chemical or engineering industries, round about sixty years ago. For myself, I should put it much further on, not earlier than thirty to forty years ago— and as a rough definition, I should take the time when atomic particles were first made industrial use of.