Telescope-Making

At Cal-tech I became acquainted with Mr. and Mrs. Crellin, who donated a chemistry building to Cal-tech named the Crellin Laboratory. He had become very wealthy as an associate of Carnegie before his retirement. At his sumptuous estate near the campus he demonstrated his hobby of telescope making and got me interested. By laboriously hand-polishing circular glass disks we could form a parabola to use in a reflecting telescope. By a simple procedure called the Foucault knife-edge test  we could use a simple light source and a razor blade to check the shape of the mirror to an accuracy of one-millionth of an inch to get it in the right shape. This always fascinated me and was worth the many hours of grinding and polishing. I didn’t have the skill that he had to manufacture an effective telescope mount but could rig up simple replacements that worked. At Cal-tech I simply didn’t have the time to use this hobby extensively, but during the year of leave while I was working in Akron, Colorado, I was able to do so. I spent a lot of time grinding a 6” telescope reflecting mirror which I mounted in a crude wood frame. I never got far enough to have the surface silvered, but even that way there was enough reflection off the glass that I could use it as a telescope and test it by having my replacement shift stopping a mile from the field and holding up fingers which I could count at that distance.