Scottish-born German astronomer noted for discovering that the magnetic field of the Earth fluctuates with a period somewhat in excess of 10 years.

In 1827 Lamont began working at the Royal Observatory, Bogenhausen, near Munich. He adopted German nationality and worked at Bogenhausen for the rest of his life, as director of the observatory from 1835 and also as professor of astronomy at the University of Munich from 1852. In addition to his other work, he determined the orbits of Saturn's satellites Enceladus and Tethys, the periods of Uranus' satellites Ariel and Titan, and the mass of Uranus. He also cataloged more than 34,000 stars. He established a magnetic observatory at Bogenhausen in 1840 and 10 years later discovered the variation in the Earth's magnetic field. In 1862 he discovered the existence of large-scale surges of electrical charge within the Earth's crust that are associated with ionospheric disturbances. Lamont's most noteworthy work is Handbuch des Erdmagnetismus (1849; “Handbook of Terrestrial Magnetism”). He was elected a foreign member of the Royal Society of London in 1852.