An Original Handwritten and Signed Letter from Sir David Brewster who was a Scottish Optical scientist, inventor and author. A long letter to a Dr Brown discussing not been able to meet to discuss an event with the University and the United College. Sir David Brewster 1781 – 1868 was a British scientist, inventor, author, and academic administrator. In science he is principally remembered for his experimental work in physical optics, mostly concerned with the study of the polarization of light and including the discovery of Brewster's angle. He studied the birefringence of crystals under compression and discovered photoelasticity, thereby creating the field of optical mineralogy. For this work, William Whewell dubbed him the "father of modern experimental optics" and "the Johannes Kepler of optics."Brewster was a pioneer in photography. He invented an improved stereoscope, which he called "lenticular stereoscope" and which became the first portable 3D-viewing device. He also invented the stereoscopic camera, two types of polarimeters,[ the polyzonal lens, the lighthouse illuminator, and the kaleidoscope. Size is 187mm x 112mm. Condition is good. Light folding creases. Light gum marks to rear.