An Easily Portable Episcope

Abstract

THE increasing appreciation of the value of episcopes in teaching has created a demand for an instrument, simple in construction, easy to handle, capable of being brought readily into the ordinary class room, and reasonably cheap. The Wigmore episcope which has been recently put on the market by Messrs. Newton and Co., 72, Wigmore Street, London, W.I, seems likely to meet this demand. It is light and, being provided with two carrying handles, can be easily carried from one room to another. It can be immediately installed and used in any room which has a projection screen and an electric lighting supply. In use, the episcope is simply placed upon the object to be shown on the screen; the externally mounted reversing mirror is tilted to bring the image to the required height; and the image is then brought into focus. Two 250-watt lamps are used for illuminating the field, which is 5 in. by 5 in.; but the map or drawing or book, a portion of which is to be projected, may be of any size. When the instrument is about 10 ft. from the screen, a well-illuminated picture 4 ft. square is obtained with good definition over nearly the whole of the area. The working distance may be varied from 6 ft., to 24 ft., giving pictures from 2¼ ft. to 9 ft. square, with of course a diminution in intensity at the greater distances. The episcope, which costs £12 12s., complete with lamps, should prove particularly useful for illustrating lessons in classrooms or for demonstrations in small lecture theatres, where a very large picture is not required.