Sir Harold Jeffreys was a British geophysicist who made significant contributions to mathematics and statistics. His book, Theory of Probability, which was first published in 1939, played an important role in the revival of the objective Bayesian view of probability.
Jeffreys studied for the Mathematical Tripos at St John's College, Cambridge, where he established a reputation as an excellent student: obtaining first-class marks for his papers in Part One of the Tripos, he was a Wrangler in Part Two, and in 1915 he was awarded the prestigious Smith's Prize.
In 1914 he became a Fellow of St John's College, and he retained his Fellowship until his death 75 years later. At the University of Cambridge he taught mathematics, then geophysics and finally became the Plumian Professor of Astronomy.