On the fiftieth anniversary of major discoveries at the Cavendish Laboratory Available to Purchase

This paper begins with some recollections of the Cavendish Laboratory of the University of Cambridge in the years 1928–30, which just preceded the discovery of the neutron and other major discoveries there in 1932–33. It then goes on to describe new developments in experimental techniques for accelerating, detecting, and counting charged particles such as protons and α particles in the Cavendish Laboratory which made possible the major discoveries by Chadwick, Blackett, and Cockcroft and Walton in 1932–33. The scintillation method was superseded by the linear amplifier and scale‐of‐two counter. Other experimental techniques described here include the original proportional counter, the cloud chamber triggered by coincident pulses in two Geiger–Müller counters for the detection of cosmic rays, and a 700‐kV voltage multiplier for the first transmutations by artificially accelerated hydrogen ions. Pioneer measurements on pair production of γ rays and annihilation radiation are discussed in terms of Dirac’s relativistic theory of the electron.