described. Principal Griffiths, in a recent lecture, recounts a Cambridge experience. He had been explaining to some pupils the laws of floating bodies and asked one of them to come to his laboratory in the afternoon and verify what he had been told. The man looked up with mild surprise and asked, "Do you mean to say this really comes off?" Teaching by experiment was clearly necessary.
Laboratory notebooks were written. In due course (in 1885) Glazebrook and Shaw's Practical Physics appeared, and I am glad to say after over 30 years of life is vigorous still. It has been followed by many similar books and has, I trust and believe, done much useful and important work. A man who is to develop into a physicist must have an intimate knowledge of the existing methods of physical investigation. Measurement is so important a factor in many branches of knowledge that
