' A Day at the N.P.L.' The National Physical Laboratory at Teddington is principally concerned with the general problems of exact measurement (of heat or physical dimensions, etc.) and of the properties of materials. Both of these are subjects of great importance in industry and manufacture. Today's programme is made up from recordings taken during a visit by Professor Andrade to the laboratory, when he interviewed scientists at work there. Programme introduced by Sir Charles Darwin , K.B.E., F.R.S., Director of the Laboratory. (Recording of last Friday's broadcast in the Light Programme)