Letters from George Frederick Charles Searle FRS (1864-1954) from his first letter as a student at the Cavendish Laboratory Cambridge until 1919. The letters contain interesting information on the teaching at Cambridge, and the effect of the First World War on Cambridge life. Searle worked at the Royal Aircraft Establishment during the First World War and gives details of the death of C V Burton. Searle was a lifelong friend of Heaviside and wrote a memoir about his life. He also tried to help Heaviside in his periods of financial distress. [Note: GFC Searle was a British physicist and teacher. As a child, Searle knew Clerk Maxwell, whom he considered to be a humorous individual. In 1888 he began work at the Cavendish Laboratory under J.J. Thomson, and ended up working with the laboratory for 55 years. After World War II, he ran the undergraduate laboratories. Searle is known for his work on the velocity dependence of the electromagnetic mass. This was a direct predecessor of Einstein's theory of special relativity, when several people were investigating the change of mass with velocity. Following the work of Oliver Heaviside, he defined the expression Heaviside ellipsoid, which means that the electrostatic field is contracted in the line of motion. Those developments, when modified, were ultimately important for the development of special relativity.]