Manuel Sandoval Vallarta (1899-1977). Born in Mexico City. He studied at the Massachusetts Institute of Technology (MIT), where he received his degree in science and specialised in theoretical physics (1924). With a scholarship from the Guggenheim Foundation (1927-1928), he studied physics in Berlin and Leipzig. From 1923 to 1946, he worked as an assistant, associate, and regular professor at the MIT, and guest professor at the Lovaina University in Belgium (Cooperation with Lemaître). From 1943, he divided his time between MIT and the School of Sciences and the Institute of Physics of the National Autonomous University of Mexico (UNAM). His main contributions were in mathematic methods, quantum mechanics, general relativity and, from 1932, cosmic rays.