Science and research. Mineral prospecting. Intensity of the earth's magnetic field, something a mining engineer needs to know if he is looking for vital metals under the crust of the earth, may be measured by the horizontal magnetometer and the vertical magnetometer shown here. Three engineering students employ geophysical methods, which they will use after they complete their training courses, for war jobs in the minerals industry or commission in the armed forces. Their knowledge will be applied to airplane detection and anti-submarine warfare. Most of the students are now in the enlisted reserve. Colorado School of Mines, Golden, Colorado. Sourced from the Library of Congress.