Ernst Mach was a Moravian-born Austrian physicist and philosopher, who contributed to the physics of shock waves. The ratio of one's speed to that of sound is named the Mach number in his honor. As a philosopher of science, he was a major influence on logical positivism and American pragmatism. Through his criticism of Newton's theories of space and time, he foreshadowed Einstein's theory of relativity.Included in this compilation are a set of scientific lectures that were intended to popularize science in the late 19th and early 20th century. Now in the twenty-first century, and scientific literacy falling to an all-time low, a call to popularize science could not be more needed.