A LECTURE entitled “Optics Applied to Engineering” was delivered by Mr. K. J. Habell at a meeting of the Leicester Branch of the Association of Scientific Workers held on June 2 at the College of Technology, Leicester. Mr. Habell described the principles of several types of optical instruments now in increasing use in engineering workshops, and much interest was shown in those of the more difficult types of profile projection. The application of telecentric systems for the avoidance of magnification errors due to incorrect focusing and to ensure the imagery of the correct profile was very well illustrated by diagrammatic and experimental slides showing the images of a circular hole produced by convergent, divergent and collimated beams of light. Other instruments described included the tool-room microscope for the examination of form tools and screw-thread forms, and alignment telescopes for measuring the alignment and relative tilt of closely or widely separated bearings and jigs. Details were given of auto-collimating telescopes for high precision work in angular measurement. The importance to the war effort of instruments of the types described was emphasized. A selection of the instruments was on view, and was demonstrated after the meeting.