ELECTRICAL EXHIBITION AT PHILADELPHIA. 



307 



transformer of energy we have, being thirty- 

 ei^ht times more efficient than the boiler, and 

 six times more efficient than the steam-engine. 

 Storage-Batteries. The storage-batteries at- 

 tracted a great deal of attention, principally 

 because of the late improvements, which seemed 

 to give promise of practical use in the econom- 

 ical storage of power. This, however, is not 

 true. A storage- battery gives only about 40 

 per cent, of the power put into it, and the lead 

 plates of which the battery is built soon disin- 

 tegrate, and the battsry becomes useless. The 

 most important of these batteries was one ex- 

 hibited by the Brush Company. It consists of 

 twenty- one cells, each of which is composed of 



BRUSH STREET-LAMP. 



three plates of cast-lead, the central one being 

 :in oxygen plate, and those on either side hy- 

 drogen. The plates measure sixteen by sixteen 

 inches, and the two outer ones are connected, 

 while the middle plate is connected with the 

 outside plate of the next cell ; so the hydrogen 



and oxygen plates alternate. This is known as 

 " connecting in series." The action within the 

 cell while storing electricity is chemical. It 

 causes one atom of PbO 2 , with which the posi- 

 tive or hydrogen plate is coated, to pass over 

 to the negative lead plate, there producing 

 PbO. This renders both plates alike. Other 

 chemical actions take place ; but this transfer- 

 ence of the oxygen- atom from the peroxide to 

 the lead is the essential action. This, how- 

 ever, occurs in the presence of sulphuric acid, 

 which unites with the newly formed oxide of 

 lead, producing the sulphate of lead in a white 

 film, insoluble in the dilute acid. We have 

 chemically the following changes : Pb + PbO 2 

 becomes PbO + PbO, and then PbO + H 2 SO 4 

 becomes PbS0 4 + H 2 O. This is the chemical 

 action that takes place when discharging; and 

 when there is no trace of electricity flowing 

 from the terminals the battery is in its original 

 condition. Several motors for'sewing-machines 

 were run by the batteries manufactured by the 

 Brush Company, and a room in this exhibition 

 was lighted very satisfactorily with currents 

 supplied by these batteries. 



Since the dynamo is a reversible machine 

 that is, instead of power being applied to the 

 pulley to develop electricity, electricity may 

 be sent through the armature to cause it to 

 rotate and give out power several motors 

 were exhibited, varying from one hundredth 

 of a horse-power up to six horse-power. Mr. 

 Daft exhibited a motor with a Siemens arma- 

 ture. The speed of the armature's shaft was 

 reduced by an endless screw working into a 

 cog-wheel. On the shaft with this cog-wheel 

 was mounted a pulley, and this ran the print- 

 ing-press that printed the "Electrical World." 

 One of the motors used for sewing-machines 

 was invented by Mr. Diehls, of the Singer Com- 

 pany. The speed of revolution of the arma- 

 ture is here reduced by a new device. Instead 

 of introducing resistance into the circuit, as 

 with every other motor, the north and south 

 poles of the electro-magnets that act on the 

 armature are made to separate by a lever 

 worked by the feet. This increases the distance 

 between the poles and the armature, and con- 

 sequently decreases the magnetic effect on the 

 armature, the speed being proportional to this 

 effect. The Cleveland motor is simply a small 

 dynamo. On the same shaft with the armature 

 is a grooved pulley, which is belted to the little 

 wheel on a sewing-machine. This is started 

 by pressing on a pedal. The harder you press, 

 the faster the motor goes, for it is connected 

 with a switch that cuts out resistance in the 

 main current. It is stopped instantaneously by 

 releasing the pedal. It is said that it can pro- 

 duce one half more work in a day when the 

 electric motor is substituted for foot-power. 



Telephones, The Bell telephone exhibit was 

 historically very interesting. The original ap- 

 paratus of Bell, when compared with that of 

 Dolbear and Ries, showed in a surprising way 

 what is called the simultaneousness of inven- 



