Lawrence Nathan Hadley Jr, a member of the physics faculty at Colorado State University for more than 45 years, died on 26 January 2002 in Fort Collins, Colorado, of age-related complications. His lifelong research interest was in optical properties of materials with an emphasis on thin films.Lawrence was born on 14 October 1916 in Valley Center, Kansas. His skill at problem solving was first revealed when, as a boy, he and his father wired their home after electricity had first come to Kansas. They had holes beneath the floor in outside walls and at opposite sides of the house. The problem was to get wire from one side to the other. It was lunchtime, but Lawrence had an idea: He tied a piece of twine to the collar of one of the farm cats and tied the other end to a small board. He placed the cat in the space under the floor on one side and placed the board over the hole. After lunch they returned to find the cat on the other side of the house and it was then easy to pull the wire with the twine.Lawrence received an AB degree in physics from Friends University in Wichita, Kansas, in 1937 and an MS in physics from the University of Oklahoma in Norman in 1939. His PhD dissertation, “Reflection and Transmission Interference Filters,” was completed at the University of Michigan, Ann Arbor, in 1947 under the supervision of David Dennison.While at Michigan in 1942, Lawrence worked on the proximity fuse project for the US Navy, which included firing test objects. On occasion, retrieval was complicated when the objects landed in patches of poison ivy.After serving briefly as an assistant professor of physics at Colorado A&M (later Colorado State University) in the spring of 1947, he was appointed as an assistant professor of physics at Dartmouth College that same year. There, he enlisted a roomful of students using essentially all of Dartmouth’s early mechanical calculators to compile the 147-page document “The Transmittance and Reflectance Versus Thickness/Wavelength for Thin Films.”Lawrence returned to Colorado A&M as associate professor of physics in 1955, and was promoted to full professor in 1958. He served as the chair of Colorado’s physics department for three years, beginning in 1965. Even after his official retirement in 1987, Lawrence continued to interact with faculty and students and was a regular attendee at the weekly physics colloquium.In addition to teaching introductory physics to literally thousands of students in more than 10 000 lectures, Lawrence contributed in many other ways. He was active in the formation of the Colorado State University Research Foundation and served as both chairman of the board and as president from 1960 to 1964. Typical of Lawrence’s dedication to physics and education were his enthusiasm and skill when he guided students through a new course called “Flying Circus of Physics.” Students discussed topics ranging from “What is a water bell?” to “Why do sand dunes squeak?” In 2000, a new Foucault pendulum at Colorado State University was dedicated in Lawrence’s honor.In his spare time, Lawrence enjoyed carpentry and built several items for his house and yard. He played the organ, piano, and cello for relaxation. Lawrence will be remembered as an educator, scientist, gentleman, and gentle man.Lawrence Nathan Hadley JrPPT|High resolution© 2002 American Institute of Physics.