as they were being used (see, for example, Bowie, 1955; Howie and Timbury, 1956; Scott, 1957; Magee and Oakes, 1958; Nuffield Trust Report, 1958; Medical Research Council Report, 1959; and Wells and Whitwell, 1960). From the same work and that of others (see Bowie, 1958a and b; Alder and Gillespie, 1957; Knox and Penikett, 1958; Penikett, Rowe, and Robson, 1958; Rice, 1958; 1960; Medical Resear...