Figure 34 is a representation of the table upon which were arranged the letters of the alphabet, twenty-six in number. Each letter is represented by strips of tin foil, passing from left to right, and right to left, alternately, over a space of an inch square upon a glass table. Such parts of the tin foil are cut out, as will represent a particular letter. Thus, it will be seen that the letter A is represented by those portions of the tin foil which have been taken out, and the remaining portions answer as the conductor. P and N represent the positive and negative ends of the strips, as they pass through the table and reappear, one on each side of the small dot at A. Those two lines which have a dot between, are the ends of the negative and positive wire belonging to one of the letters. Now if a spark from a charged receiver is sent through the wires belonging to letter A, that letter will present a bright and luminous appearance of the form of the letter A. “As the passage of the electric fluid through a perfect conductor is unattended with light, and as the light or spark appears only where imperfect conductors are thrown in its way, hence the appearance of the light at those interrupted points of the tin foil; the glass upon which the conductors are pasted, being an imperfect conductor. The instant the discharge is made through the wire, the spark is seen simultaneously at each of the interruptions, or breaks, of the tin foil, constituting the letter, and the whole letter is rendered visible at once.” This table is placed at one station, and the electrical machine at the other, with 72 wires inclosed in a glass tube connecting the two stations. He could have operated with equal efficiency by using 37 wires having one wire for a common communicating wire, or with 36 wires by substituting the ground for his common wire. It does not appear that it was ever tested to any extent. _Dr. Salva’s Electric Spark Telegraph._ In 1798, Dr. Salva, in Madrid, constructed a similar telegraph, as that suggested by Reizen, (see Voigt’s Magazine, vol. 11, p. 4.) The Prince of Peace witnessed his experiments with much satisfaction, and the Infant Don Antonio engaged with Dr. Salva in improving his instruments. It is stated that his experiments were conducted through many miles. No description of his plans appear to have been given to the public. _Origin of Galvanism._ Galvanism takes its name from Galvani, Professor of Anatomy at Bologna, who discovered it in the year 1790. As the account of the circumstances attending the discovery of this useful and wonderful agent, may not be uninteresting to the reader, we insert it here as related in the “_Library of Useful Knowledge_.”