Messrs. Editors:--In a recent number of the SCIENTIFIC AMERICAN I notice an ingenious method of teaching deaf and dumb persons to converse in the dark, which is also applicable to blind mutes, and it brings to my recollection a method which was in use among the "telegraph boys" some years ago when I was one of them. Sometimes when we were visiting and asked to communicate to a "brother chip," anything that it was not advisable for the persons around us to know, a slight tap-tapping on the table or chair would draw the attention of the party we asked to talk to, and then by his watching the forefinger of the writer, if across the room, or if near enough, by placing the hand of the writer carelessly on the shoulder of the party we desired to communicate with, the communication was written out in the telegraph alphabet or by taking hold of his hand and writing upon the finger. I think this method will be found much less complicated, if not quite as rapid, as the method with both hands, and much more convenient, as it is only necessary to have hold of one hand of the person communicated with, and is more rapid than writing with a pen. For the benefit of those not acquainted with the telegraph alphabet, I give it: A B C D E F G H I .- -... ... -.. . .-. --. .... .. J K L M N O P Q -.-. -.- --- -- -. . . ..... ..-. R S T U V W X Y . .. ... - ..- ...- .-- ..-. .. .. Z ... . The uninitiated will observe that O differs from I in the distance between the dots, made thus: I by two quick strokes of the forefinger; O by one quick stroke, slight pause, and another quick stroke; the dashes are made by holding the finger down for a short space: thus SCIENTIFIC AMERICAN would be written: S C I E N T I F I C ... .. . .. . -. - .. .-. .. .. . A M E R I C A N .- -- . . .. .. .. . .- -. In a very short time any one can learn to read by the sight or by the touch. Anything which can add to the pleasure or comfort of these unfortunates is of importance. MAGNET