CD 2478048 E&MP12.020
Electric Appliances & Apparatus
April 30, 1932
College professors no longer need to take their old-time fishpole to class when they deliver a lecture. Now they can "pack" an electric gun, that shoots little arrows of light onto a motion picture or lantern slide screen.
In fact, the lecturer can sit in the second or third row in an auditorium and by the simple expedient of pressing a switch project a white arrow upon any part of the screen he desires without moving from his seat or getting himself between the audience and the screen.
The electric pointer, developed by F.A. Benford, of the General Electric research laboratory in Schenectady, consist of a nozzle very similar to that found on a garden hose, except that it is a little longer. Made of aluminum, it is light in weight, and to its handle is attached a lead which can be plugged into any convenient outlet.
In the far end of the pointer is an objective lens, halfway toward the handle a condensing lens, and between these two a diaphragm, or small slide, with the arrow on it.
A 125-watt lamp is used in the device to obtain the intense light necessary, for the arrow can be seen even when projected against the white of the slide.
A small switch on the handle of the pointer turns on the arrow, and a push button informs the operator of the projector when the slides shall be changed.
Thanks to the electric pointer, the lecturer can see his own slides from a suitable distance -- probably for the first time in the history of lecturing.
Original Caption by Science Service