Vesto Slipher (1875–1969) was born in Mulberry, Indiana. He received his undergraduate degree in mechanics and astronomy at Indiana University before taking a position at the Lowell Observatory in Flagstaff, Arizona in 1901, where he would spend the rest of his career. In the mean time, he received his doctorate from Indiana University in 1909. While at the Lowell Observatory, Slipher’s work focused on employing and improving spectrographic techniques to study planetary atmospheres and spiral nebulae. Slipher’s discovery of the doppler shift of galactic spectra, and the enormous galactic velocities which these measurements implied, was instrumental in revealing the expansion of the universe and in the formulation of Hubble’s Law. The reading that follows was published in 1917 in the Proceedings of the American Philosophical Society.