Progress in electrical science is daily causing the world to open its eyes in wonder and the scientist to enlarge his hopes for yet greater achievements. The practical uses to which this subtile fluid, electricity, is being put are causing changes to be made in time-tested methods of doing things in domestic, scientific, and business circles, and the time has passed when startling propositions to accomplish this or that by the assistance of electricity are dismissed with incredulous smiles. This being the case, no surprise need follow the announcement of a device to facilitate the imparting of instruction to deaf children which calls into requisition some service from electricity.
The sense of touch is the direct medium contemplated, and it is intended to convey, with accuracy and rapidity, messages from the operator (the teacher) to the whole class simultaneously by electrical transmission.
[Footnote 1: By the same means two deaf-mutes, miles apart, might converse with each other, and the greatest difficulty in the way of a deaf-mute becoming a telegraph operator, that of receiving messages, would be removed. The latter possibilities are incidentally mentioned merely as of scientific interest, and not because of their immediate practical value. The first mentioned use to which the device may be applied is the one considered by the writer as possibly of practical value, the consideration of which suggested the appliance to him.]
An alphabet is formed upon the palm of the left hand and the inner side of the fingers, as shown by the accompanying cut, which, to those becoming familiar with it, requires but a touch upon a certain point of the hand to indicate a certain letter of the alphabet.
A rapid succession of touches upon various points of the hand is all that is necessary in spelling a sentence. The left hand is the one upon which the imaginary alphabet is formed, merely to leave the right hand free to operate without change of position when two persons only are conversing face to face.
The formation of the alphabet here figured is on the same principle as one invented by George Dalgarno, a Scottish schoolmaster, in the year 1680, a cut of which maybe seen on page 19 of vol. ix. of the Annals, accompanying the reprint of a work entitled "Didascalocophus." Dalgarno's idea could only have been an alphabet to be used in conversation between two persons tête à tête, and--except to a limited extent in the Horace Mann School and in Professor Bell's teaching--has not come into service in the instruction of deaf-mutes or as a means of conversation. There seems to have been no special design or system in the arrangement of the alphabet into groups of letters oftenest appearing together, and in several instances the proximity would seriously interfere with distinct spelling; for instance, the group "u," "y," "g," is formed upon the extreme joint of the little finger. The slight discoverable system that seems to attach to his arrangement of the letters is the placing of the vowels in order upon the points of the fingers successively, beginning with the thumb, intended, as we suppose, to be of mnemonic assistance to the learner. Such assistance is hardly necessary, as a pupil will learn one arrangement about as rapidly as another.
If any arrangement has advantage over another, we consider it the one which has so grouped the letters as to admit of an increased rapidity of manipulation. The arrangement of the above alphabet, it is believed, does admit of this. Yet it is not claimed that it is as perfect as the test of actual use may yet make it. Improvements in the arrangement will, doubtless, suggest themselves, when the alterations can be made with little need of affecting the principle.
In order to transmit a message by this alphabet, the following described appliance is suggested: A matrix of cast iron, or made of any suitable material, into which the person receiving the message (the pupil) places his left hand, palm down, is fixed to the table or desk. The matrix, fitting the hand, has twenty-six holes in it, corresponding in position to the points upon the hand assigned to the different letters of the alphabet. In these holes are small styles, or sharp points, which are so placed as but slightly to touch the hand. Connected with each style is a short line of wire, the other end of which is connected with a principal wire leading to the desk of the operator (the teacher), and there so arranged as to admit of opening and closing the circuit of an electric current at will by the simple touch of a button, and thereby producing along the line of that particular wire simultaneous electric impulses, intended to act mechanically upon all the styles connected with it. By these impulses, produced by the will of the sender, the styles are driven upward with a quick motion, but with only sufficient force to be felt and located upon the hand by the recipient.
Twenty-six of these principal or primary wires are run from the teacher's desk (there connected with as many buttons) under the floor along the line of pupils' desks. From each matrix upon the desk run twenty-six secondary wires down to and severally connecting with the twenty-six primary wires under the floor. The whole system of wires is incased so as to be out of sight and possibility of contact with foreign substances. The keys or buttons upon the desk of the teacher are systematically arranged, somewhat after the order of those of the type writer, which allows the use of either one or both hands of the operator, and of the greatest attainable speed in manipulation. The buttons are labeled "a," "b," "c," etc., to "z," and an electric current over the primary wire running from a certain button (say the one labeled "a") affects only those secondary wires connected with the styles that, when excited, produce upon the particular spot of the hands of the receivers the tactile impression to be interpreted as "a." And so, whenever the sender touches any of the buttons on his desk, immediately each member of the class feels upon the palm of his hand the impression meant to be conveyed.
The contrivance will admit of being operated with as great rapidity as it is probable human dexterity could achieve, i.e., as the strokes of an electric bell. It was first thought of conveying the impressions directly by slight electric shocks, without the intervention of further mechanical apparatus, but owing to a doubt as to the physical effect that might be produced upon the persons receiving, and as to whether the nerves might not in time become partly paralyzed or so inured to the effect as to require a stronger and stronger current, that idea was abandoned, and the one described adopted. A diagram of the apparatus was submitted to a skillful electrical engineer and machinist of Hartford, who gave as his opinion that the scheme was entirely feasible, and that a simple and comparatively inexpensive mechanism would produce the desired result.