From the 1981 lecture programme:
The immediate objective of measurement is to convert our observations of some aspect of the natural world into numbers. Given a reference standard, when we have measured something we then have information by which we can duplicate it in another place or at another time. This makes possible mass production, with different components being made in different factories, so that components will fit together when assembled in a third factory; without this capability, modern industrial society could not have evolved. The other main application of measurement, certainly no less important, is in making it much easier for scientists to reason about their observations: for once an observation has been expressed as a number, the full power of mathematics and computation, which in this respect can be regarded as a form of shorthand reasoning, can be brought to bear on it.
We have therefore as a first step to consider number systems, and to remark the great advance made in the decimal system, with its incorporation of the sign for zero. Further, the binary system now has a special significance, since numbers when expressed in the scale-of-two are easily handled by electronic circuits and therefore by computers.
Conversion of observations into numbers is, however, possible only if we agree on some standard by which some property such as length or time isto be measured. We have therefore to consider the qualities required in a standard, and to look at the evolution of standards in the course of history. These are, for example, mentioned in Magna Carta; and a major new system of standards sponsored by the French revolutionaries became the metric system.
Exact measurement can only be achieved at a price; to advance in exactness, we need to pay by taking extra time or trouble or by exerting greater powers of ingenuity and invention. But nature is a fair-minded opponent, who will yield further secrets to intelligently directed effort.
Examples of the value of simple methods of measurement will feature in the lecture.