8.5x4 Folded page signed "To Mr. Jim Wiggins with my compliments Walter M. Elsasser 4/3/72" in black fountain pen ink. In very good condition. (1904-1991) Walter Maurice Elsasser was a German-born American physicist, a developer of the presently accepted dynamo theory as an explanation of the Earth's magnetism. He proposed that this magnetic field resulted from electric currents induced in the fluid outer core of the Earth. He revealed the history of the Earth's magnetic field by the study of the magnetic orientation of minerals in rocks. He was also the first to suggest that the wave-like nature of matter might be investigated by electron scattering experiments using crystalline solids.This lot came from the Jim Wiggins collection we purchased in July 2022. Jim Wiggins accumulated the most unique and valuable autograph collection over a period of 70-plus years. He obtained his collection either in person or by writing to persons of fame and notoriety. Comes with a full Letter of Authenticity from Todd Mueller Authentics.Comes with a full Letter of Authenticity from Todd Mueller Authentics.