H. MIDDLETON, "Seeing by telegraph.
To the Editor of The Times",
The Times, 24 April 1880.
Sir, - As I described an instrument for this purpose in a paper read before the Cambridge Philosophical Society on the 8th ult., I beg that you will publish this short account, which professes to give a solution of the problem.
Construction of an electrical telescope. - A lens is used to throw on a plane or suitably curved receiving plate (enclosed in a camera) the image of any object. The receiving plate of the camera is composed of thermopile elements, ground to a smooth surface, and having their posterior faces put in electrical communication by a system of wires with a somewhat similarly constructed plate. The beating, &c., of electricity, which flow through the wire system and on reaching the second thermopile plate are reconverted into beat, &c., according to the law discovered by Peltier, the amounts of beat, &c, being directly proportional to the amount of electricity.
Moreover, according to the manner in which the elements of the plates are arranged with respect to each other, we can get a "positive" or "negative" (to use the ordinary phraseology of photography) picture on the second receiving plate, since the Peltier effect here holds and the copy of the radiant heat and light which corresponding points of the picture and copy send to the eye.
Furthemore, these images can be either viewed directly or by reflected light (after the fashion of the Japanese mirrors and projection on a screen), or by suitable apparatus they can be retained as photograph, a thermograph or chemicograph, the details of which will be found in the paper alluded to, and of which an abstract will, I believe, soon appear in the proceedings of the Cambridge Philosophical Society. Also, I touched upon the method of attacking the problem of photographing in colours and in conclusion pointed out a striking analogy between the camera of the instrument and that of the human eye ; the thermoelectric elements of the instrument and the rods and cones of the eye ; the conducting system of insulated wires emanating from the plate of the instrument and the optic nerve (or bundle of conducting fibres of the eye) - supposing that as the electric currents in the instruments effected a registration on the sensitive paper, so in the eye the nerve currents to the optic nerve probably leave some brain trace on the mind.
I remain, Sir yours, &c.,
St. John's College, Cambridge, April 22.