270 



SCIENCE. 



[Vol. XII. No. 305 



taique," describes this novel and promising battery. The positive 

 electrodes are porous plates made by submitting finely divided cop- 

 per to a pressure of 600 kilograms per square centimetre. The 

 negative electrodes are tinned iron plates, which are amalgamated, 

 the object of the tin being to hold the mercury, which does not ad- 

 here to iron. The receptacle is made of tinned sheet steel. The 

 negative electrode rests on the bottom of the box, with which it is 

 in contact. The following table shows the composition of the 

 electrolyte ; — 



Zinc 144.67 



Potash in solution 209.82 



Potash, free 313.72 



The positive electrodes are enveloped in parchment paper, and 

 are insulated from the negatives by glass rods. Without the parch- 

 ment, the action is irregular, the oxidation of the positive is not 

 complete, and deposits of zinc are mixed with the copper : hence 

 want of adherence, and local action or short circuits through the 

 formation of ' trees," as in other batteries where metallic deposition 

 takes place. The following data are the results of tests made in 

 the laboratory of the inventors : — 



Weight of cell in working order ,22.05 pounds. 



" '' 5 posilive plates 4.25 " 



" " 6 negative *' 2.32 " 



Height of positive plate 11.02 inches. 



Width " " " 4.92 " 



Height of negative plate 11.81 " 



Width " " '* 4.92 ** 



Surface of positive 54.22 sq. m. 



" ^' negative 58.10 " 



Length of receptacle 5.90 inches. 



Width " " 3.35 " 



Height" " 15.75 



Weight " " 2.20 pound.s. 



Electrolyte (specific gravity, 1.55) weight 13.224 '* 



Useful electro-motive force 75 volt. 



Current, charging 15 amperes. 



" discharging 48 " 



Time of charging 30 hours. 



'* '* discharging 9.5 '' 



U-£"' capacity ^'^^SlfZ^. 



Capacity per pound of cell j f-\l ^"ft^hourT'^' 



Weight per horse-power hour 52.47 pounds. 



According to a note of M. Krebs, however, the total weight of 

 battery for a horse-power hour was found to be 87.55 pounds. 



The Edison Electric-Lighting System in Berlin. — 

 According to Industries, the work of the Edison Company in Ber- 

 lin has been so successful that the public and the municipal author- 

 ities have perfect confidence in their ability to extend their central- 

 station work still further, and a concession has been given for the 

 establishment of two new stations. Both stations must be ready 

 within two years, and each must be able to supply current for 6,000 

 glow-lamps burning simultaneously. The capacities of the two 

 stations are to be eventually increased to 24,000 and 12,000 lamps. 

 The network of cables to be laid down in connection with ithese 

 stations is very complete, and practically comprises all the streets 

 of the respective districts, some small side-streets alone excepted. 

 In view of this extension of their business, the Edison Company 

 propose to increase their share capital at present by $750,000, and 

 later on by S'. 500,000. The supply of current within the districts 

 to be lighted will be compulsory, provided the customer is willing 

 to take the light for at least one year. 



The Eickemeyer Dynamo. — The Electrical Review con- 

 tains a description of a dynamo which has just been built by Mr. 

 Eickemeyer, to be used in ' forming ' the plates of storage-batteries. 

 The novelty of this machine lies in the fact that both the armature 

 and magnet coils are surrounded by a heavy casing of cast iron. 

 The advantage of the type lies in the fact that there is no chance 

 for Imes of force to take any other path than through the armature, 

 so that all magnetic leakage is avoided. The dynamo is to give 40 

 amperes at 1,000 volts. Its weight is 6,000 pounds, the principal 

 part of which is in the cast-iron casing. The armature is of the 

 drum type, 18 inches in diameter by 15 inches long. There are 

 240 turns of No. 11 wire, making a single layer on the armature. 



The machine is shunt-wound, and the following data are given, 

 as to its performance : — 



Armature 240 turns, 1,560 feet No. 11 wire. 



" resistance 0.57 ohms. 



Field 14,880 turns, No. 21 wire. 



" resistance 1,600 ohms. 



Speed S50 revolutions. 



Electro-motive force at terminals 1,000 volts. 



" '' " per foot of wire ... . 1.28 " 



Current in external circuit 40 amperes. 



" ''field .625 '* 



Energy absorbed in field 612 watts. 



" " "armature 912 " 



" " " friction, etc 600 " 



Net commercial efficiency 94.5 percent. 



The machine is said to run beautifully, with no sparking at full 

 load. Its efficiency is more than good ; and the dynamo is simple 

 in construction, and cheap. 



Trial of an Electric Locomotive at Birmingham,. 

 England. — The following description of a trial of an electric- 

 locomotive is given in Industries : " The trial trip of an electric 

 locomotive for drawing the tram-cars of the Birmingham Central 

 Tramways Company took place in the presence of a large number 

 of representatives of the press, the corporation, and of the various 

 tramway companies. The engine itself, weighing eight tons and 

 a half, has been constructed upon the Julien system by Messrs. 

 Elwell-Parker. In the trial the electric locomotive successfully re- 

 placed the steam-tram engine now in use upon the Birmingham^ 

 tramways. The gradients in many places are steep, rising to l in 

 17 ; but the electric locomotive successfully mounted this steep 

 and long ascent with a load of sixty passengers, at a speed of about 

 five miles an hour. On the level and down hill the speed could be 

 increased to ten miles an hour without difficulty; and the locomo- 

 tive was started, stopped, and backed with ease. The engine itself 

 is a very neat and compact arrangement, compared with the ordi- 

 nary tram-engines. Two rows of accumulators occupy each side, 

 between which is the alley for the driver, where is fixed the switch,, 

 the reversing-switch, the engine-brake, and the car-brake. The 

 switch connects the cells in five sets, all parallel, and two, three, or 

 four in series. The cells number 104, having 39 plates, each 9 

 inches by 6 inches. The motor is placed low down, and is con- 

 nected to the axles by helical gearing, — geared I to 8+. The en- 

 gine is capable of exerting 40-horse power, and will run sixty or 

 seventy miles. A contract has been entered into by the engineers 

 to run this car for three months at twelve cents per car-mile, the 

 present cost of steam being nearly sixteen cents. 



Electric-Lighting. — The establishment of central stations 

 for the distribution of incandescent electric-lighting has received a 

 noticeable impetus through the successful introduction of the 

 alternating current and transformer method of distribution. The 

 saving in the cost of conductors effected by this method, due to 

 the employment of relatively high potential currents in the mains, 

 has rendered it commercially practicable to distribute over much 

 larger areas than formerly, but over areas of relatively sparse con- 

 sumption. Thus many small towns are enabled to maintain suc- 

 cessfully electric-lighting stations. The Westinghouse Electric 

 Company of Pittsburgh, Penn., introduced the alternating-current 

 system here, after careful and thorough investigation and experi- 

 ment, about two years ago, installing the first commercial station- 

 at Buffalo, N.Y., and putting it in operation Thanksgiving Day,. 

 1886. The number of central-station plants since supplied or con- 

 tracted for by the Westinghouse Company has reached no fewer 

 than one hundred and twenty-four. They have recently received 

 a contract for a station in the heart of London, to include an outfit 

 for twenty-five thousand lamps. This contract is with the Metro- 

 politan Electrical Supply Company, Limited, the organization of 

 which in London was noticed in electrical journals some months 



An Electric Surface Road in New York. — The Bentley- 

 Knight Electric Railway Company will soon resume operations on 

 the Fulton Street cross-town railway in this city, and expect to- 

 have it in operation before the end of this month. They began 

 work on the road over a year ago, but, owing to the opposition of a. 



