ELECTRICITY DURING THE NINETEENTH CENTURY. 343 



purpose in directiug the attention of the world to the possibilities of 

 the electric arc in lighting'. 



Inventors in America were not idle. By the close of 1878 Brush of 

 Cleveland had brought out his series system of arc lights, including 

 special dynamos, lamps, etc.. and by the middle of 18T9 had in opera- 

 tion machines, each capable of maintaining sixteen arc lamps on one 

 wire. This was indeed a great achievement for that time. \\%\ston, 

 of Newark, had also in operation circuits of arc lamps, and the Thomson- 

 Houston system had just started in commercial work with eight arc 

 lamps in series from a single dj^namo. Maxim and Fuller in New 

 York were working arc lamps from their machines, and capital was 

 being rapidly invested in new enterprises for electric lighting. Some 

 of the great electric manufacturing concerns of to-day had their begin- 

 ning at that time. Central lighting stations began to be established 

 in cities, and the use of arc lights in street illumination and in stores 

 grew rapidly. More perfect forms of light arc lamps were invented, 

 better generating dynamos and regulating apparatus brought out. 

 Factories for arc-light carbon making were built. The tirst special 

 electrical exhibition was held in Paris in 1881. In the early eighties 

 also the business of arc lighting had become firmly established and 

 soon the bulk of the work was done under two of the leading systems. 

 These were afterwards brought together under one control, thus secur- 

 ing in the apparatus manufactured a combination of the good features 

 of both. Until about 1892 nearly all the arc lamps in use were worked 

 under the series system, in which the lights were connected one after 

 another on a circuit and traversed by the same current. This current 

 has a standard value or is a constant current. Sometimes as many as 

 a hundred lamps were on one wire. As the mains for the sup[)ly of 

 incandescent lamps at constant pressure or potential were extended 

 attention was more strongly turned to the possibility of working arc 

 lights therefrom. 



Within a few years of the close of the century this placing of arc 

 lamps in branches from the same mains which supply incandescent 

 lamps became common, and the inclosure of the arc in a partially air- 

 tight globe, a procedure advocated by Staite in 1847, was revived by 

 Howard, Marks, and others for saving carbons and attention to the 

 lamp. The inclosed arc lamp was also found to be especially adapted 

 to use in branches of the incandescent lamp circuits, which had m cities 

 oecome greatly extended. The increasing employment of alternating 

 currents in the distribution of electric energy has led also to the use of 

 alternating current arc lamps, and special current-regulating apparatus 

 is now being applied on a large scale to extended circuits of these 

 lamps. It can be seen from these facts that the art is still rapidly pro- 

 gressing and the field ever widening. A little over twenM" years ago 

 practically no arc lamps were used. Now, at the close of the century, 



