Henry Beaumont Leeson

[1] Leeson studied medicine at St Thomas's Hospital in London, and graduated M.D.

From 1840 to 1852 he acted as physician and lecturer on Chemistry and Forensic Medicine, at St Thomas's.

His optical apparatus was innovative, and he developed a double refracting goniometer, also known as a Leeson prism.

It was made from Iceland spar, and later applied to the measurement of angles in small crystals.

Leeson's goniometer, to be fitted to a microscope eyepiece, was illustrated in Knight's New Mechanical Dictionary (1884);[8] and its measurement technique, by bringing two images of a crystal into coincidence, was still explained in a text of 1921.

Pulpit Rock, Bonchurch, Isle of Wight; 1849 engraving by William Bernard Cooke .
Views of a Leeson goniometer. The double refracting crystal was at a . From John Quekett 's Practical Treatise on the Use of the Microscope (1852). The text comments that a Rochon prism could also be used.