(1901–1971) British crystallographer
Bernal's family were farmers in Nenagh, now in the Republic of Ireland; his mother was an American journalist. He was educated at Cambridge University, where his first work on crystallography was done as an undergraduate on the mathematical theory of crystal symmetry. William Bragg offered him a post at the Royal Institution, which he joined in 1922.
Bernal was one of the most influential scientists of his generation. He had decided early in his career that x-ray crystallography would turn out to be the most likely tool to reveal details of the structure of matter. In addition to his intellectual mastery of the subject, he also possessed the ability to transmit his own enthusiasm to others and to attract around him a large number of highly talented and ambitious colleagues.To this group he was always known as ‘Sage’.
His first success came in 1924 when he worked out the structure of graphite. He also began to work on bronze. In 1927 Bernal moved to Cambridge to a newly created lectureship in structural crystallography. While at Cambridge he worked on the structure of vitamin B1 (1933), pepsin (1934), vitamin D2 (1935), the sterols (1936), and the tobacco mosaic virus (1937).
Much of this research came not from Bernal alone; in most of his Cambridge studies he collaborated closely with Dorothy Hodgkinand many others came to work with Bernal, including Max Perutz, Francis Crick, and Rosalind Franklin.
In 1937 he was appointed professor of physics at Birkbeck College, London. With the outbreak of war in 1939 he joined the Ministry of Home Security and carried out with Solly Zuckerman an important analysis of the effects of enemy bombing. Later in the war he served as scientific adviser to Lord Mountbatten, the Chief of Combined Operations. Bernal's main duties were connected with the planned Normandy landings. He spent much time establishing the physical condition of the beaches the Allies would land on in 1944. Maps, he soon discovered, were inaccurate. “Do you realize,” he would tell his staff, “no one knows where France is?” He was one of the first to land on the beaches on D-day.
Bernal's duties were performed despite the fact that he was one of Britain's best known communists, having joined the party in 1924. While many of his friends abandoned the party at some stage of their life, some because of the Stalinist purges, others because of the Molotov pact, and most of those remaining because of the Hungarian uprising, Bernal remained with the party throughout his life. He traveled frequently in Eastern Europe, Russia, and China, and he was probably the only significant Western scientist to give permanent support to the work of Lysenko.
In 1963 Bernal suffered the first of several serious strokes. He became progressively less mobile and in the last two years of his life, unable to speak, he was confined to a wheelchair.