Self-portrait of Lord Rayleigh (1842-1919), physicist and Nobel laureate, made in 1870. Born John Strutt, he inherited the title Baron Rayleigh in 1873. Rayleigh had a laboratory at the family mansion where he conducted meticulous experiments in physics. His book The Theory of Sound" is considered a masterpiece of classical physics. Eventually he moved to Cambridge, where his work included the study of energy levels in light and investigations of gas theories. His study of Prout's hypotheses led to Rayleigh's theories on gas densities and to the discovery of argon by Ramsay. Rayleigh was awarded the 1904 Nobel prize for physics for this later work."