George Ellery Hale (1868 –1938) was an American solar astronomer. As an undergraduate at MIT, he was known for inventing the spectrohelioscope, with which he made his discovery of solar vortices. The results of his research in sunspot magnetic fields is now commonly referred to as "Hale's law." This edition includes the personal papers and correspondence with scientists around the world, much of it relating to national and international development of astrophysics, and the history of the Mount Wilson and Palomar observatories.