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.[1] [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