square and inch thick, and are cast in groups of four, these groups being united by portions, having, say, to inch thickness. For positives, the fused mass is cast in separate lozenges, each lozenge having a bevelled V-shaped periphery. These cut squares or lozenges are then placed in a suitable mould, and a molten mixture of lead and antimony, in proper proportions, is cast about them under high pressure, thus fixing them securely in a firm lead framing of somewhat more than the usual density. (The feature of casting under pressure is an improvement in manufacture, due to Mr. H. Lloyd, who is connected with the American makers, and the process. is protected by patents granted to him). The connecting sheets of the squares making up a group and the V-shaped bevel of the lozenge serve to make their solidity of fixation exceedingly good. The frameworks containing the chloride castings are then placed in a dilute solution of zinc chloride, together with plates of zinc, the frames and zinc plates being alternated with one another and in metallic contact. This combination is the equivalent of a primary battery "dead shortcircuited." The chemical reactions which occur, result in the removal of the zinc chloride and the chlorine of the lead, and there remains finally the dense framing containing squares or lozenges of spongy lead, which plates are then "formed" in, practically, the usual manner. If a section of the spongy lead thus made, be examined, it is found that the metal is in a crystalline condition, and that the crystals are all uniformly arranged with their longer axes perpendicular to the surface of the plate. This provides interstices, so that the changes of volume occurring in the chemical reactions of electrolysis, may take place without exerting lateral pressure upon the crystals, or otherwise crowding them into a condition of break-up. These crystals are not, of course, mechanically and irregularly bound together, but are related to one another according to the laws of molecular formation, and are, consequently, much more strongly bound together than if they had been mechanically combined. Furthermore, this crystalline structure presents the maximum obtainable surface for the given mass, an infinite number of inter-crystallic channels passing all through the material and the entire plate being of the same thoroughly spongy consistency, except in those small portions where the continuous lead framing is encountered. The effect of this extreme porosity and surface area is to give the battery a maximum capacity for a given weight and size of cell, an item of great importance when considered with reference to the demands of traction. Very heavy discharges also can be taken from this battery, owing to the interstices between the crystals permitting changes of volume to occur without mechanical violence to the structure. While the method of construction just described seems to accomplish its anti-disintegrating function perfectly, it has been thought best by the manufacturers, in order that there shall be no doubt about the matter, to introduce between the plates a thin sheet of acid-proof fabric, so that any small particles which might fall away, could not make metallic contact with two adjacent plates and thus shortcircuit the cell. The fabric chosen for this purpose is woven asbestos cloth. It might be thought that the introduction of this asbestos would considerably increase the internal resistance of the cell, but the fact is otherwise, the resistance of the cell being not appreciably higher than that of other lead cells. This is undoubtedly due to the fact that the larger part of the resistance of most lead cells is that caused by poor contact between the lead framing and the paste placed in it. In the chloride battery this contact is exceptionally good, owing to the pastilles of chloride being so firmly bound by the framing cast under pressure as to compensate for any resistance due to the asbestos. These batteries are, and have been for several years, operating successfully and in very large numbers in the city of Paris as a source of current for lighting purposes. A large plant has been in operation in this city in the building of the Provident Life and Trust Company for a year past, and a very large one has been installed at the station of the Germantown Electric Light Company, where it is said to have given, thus far, entire satisfaction. The manufacture of this battery is protected by a large number of patents of the United States and of foreign countries, a list of which is hereto appended.* The essential features of the process of manufacture, however, are covered by the patents granted to Mr. Clement Payen. Believing that this battery is a noteworthy and meritorious improvement upon many other forms of lead battery, tending to greater durability, greater capacity without increase of weight, and making possible heavier discharges without injury, the Institute, therefore, recommends the award of the John Scott Legacy Premium and Medal to to Clement Payen, the inventor. * Accessible for reference in the records of the Committee on Science and the Arts. Adopted at a meeting of the Committee on Science and the Arts, held Wednesday, June 28, 1894. JOSEPH M. WILSON, President. Countersigned by ARTHUR BEARDSLEY, Chairman of the Committee on Science and the Arts. APPENDIX. The accompanying illustrations are introduced by way of explanation of the text of the foregoing report. Fig. 1 gives a clear idea of the appearance and shape of the plates. Fig. 2 represents two cells of the chloride accumulator with a portion of the tank broken away to exhibit the disposition of the individual elements. The cut also shows clearly the manner of connecting up the elements and cells. The curves, Figs. 3 and 4, shown herewith, exhibit the working capacity and electrical efficiency of the chloride accumulator, and their interpretation will present no difficulties to the electrician. WURTS' LIGHTNING ARRESTERS FOR THE [Being the report of the Committee on Science and the Arts on the improvements in Lightning Arresters invented by Alexander Jay Wurts.] HALL OF THE FRANKLIN INSTITUTE, PHILADELPHIA, April 3, 1894. The Franklin Institute of the State of Pennsylvania for the promotion of the Mechanic Arts, acting through its Committee on Science and the Arts, investigating "Wurts' Lightning Arresters," finds as follows: The Institute, through a sub-committee appointed for the purpose, has carefully examined the claims set forth for these inventions as embodied in specimen arresters sub mitted, copies of patents granted and literature relating thereto. A considerable number of reports of effective operation have also been examined. The various arresters produced by Mr. Wurts are intended for the protection of electric lighting and power circuits from direct and indirect damage from lightning discharges, and Mr. Wurtz has, apparently, studied this question in a scientific and very exhaustive manner. With but few exceptions, all lightning arresters commonly used, up to the inventions of Mr. Wurts, have been based upon the fact that static discharges generally tend to "ground" by the shortest distance-even when obliged, in order to do this, to jump a considerable "air gap "-in preference to taking a longer path over a much lower resistSuch arresters, therefore, have been essentially nothing more than two points or sets of points, one being grounded" and the other connected to one or both legs of the circuit to be protected. ance. 66 An arrester of this kind, while often affording a release from the static charge, would also allow the dynamo current to follow upon the arc so produced, thus producing either short-circuit or a dangerous "ground," and in both cases causing an interruption of the main working circuit. Hence, the more improved arresters of this type were so constructed as to break this dynamo arc as soon as possible. This is easily seen to be a remedy rather than a preventive. Mr. Wurts perceived this fact and set himself the problem of constructing an arrester in which the dynamo arc could not start, rather than one which would break the are when started. As far as can be judged from recorded data, he has succeeded in solving the problem in a very efficient manner, both for alternating and direct currents. We shall consider the separate forms separately. The "Non-arcing" Metal Alternating Arrester.-This arrester, although the simplest in construction, is perhaps, the most notable of all Mr. Wurts' arresters. It consists simply of seven cylinders of metal, each one inch in diameter, and three inches long. These cylinders are mounted side by side, and separated from one another by of an inch. The |