The first building of the Cavendish Laboratory at Cambridge University, England, was opened in 1874 and its first professors were James Clark Maxwell, Lord Rayleigh, and J. J. Thomson. It was in this Laboratory that C. T. R. Wilson constructed the cloud chamber, an apparatus which has perhaps had more influence on the development of atomic physics than any other single piece of equipment; it was here that F. W. Aston developed his mass spectrograph, Lord Rutherford confirmed the disintegration of nitrogen by alpha particles, Sir James Chadwick discovered the neutron, and Sir John Cockroft and E. T. S. Walton first achieved the disintegration of atomic nuclei by artificially accelerated particles.