Background
He was born on January 8, 1892 in Madison, Wisconsin, United States, the son of Mary Lousie Byrne and Charles Sumner Slichter. His mother, an erstwhile grammar school teacher, was of Scottish and Irish ancestry. His father's family, apparently of Huguenot origin and of Swiss Brethren persuasion, immigrated to Pennsylvania from Switzerland or Alsace during the eighteenth century. Charles Sumner Slichter was a professor of applied mathematics and after 1920 dean of the Graduate School of the University of Wisconsin. He did some interesting theoretical work on underground water.
Sumner Slichter's brothers also attained high achievements: one was professor of geophysics at the Massachusetts Institute of Technology and later director of the Geophysical Institute of the University of California; another was president of the Northwestern Mutual Life Insurance Company; and the third established and owned his own steel foundry in Milwaukee.
Slichter spent his boyhood in Madison during the heyday of the La Follette reform movement. He retained a lifelong enthusiasm for the midwestern cultural tradition and regularly returned to his summer home on Lake Mendota.