ELECTEIC LIGHTING. 



obtained from plants grown in northern lati- 

 tudes, the flavor of vegetables like onions .and 

 celery is much more pungent, and the aroma 

 and flavor of berries, plums, and other fruits, 

 much more pronounced. The formation of 

 sugar is dependent upon heat, and therefore 

 the fruits of this climate are very deficient in 

 sweetness. Flowers when transplanted from 

 more southerly climates attain an unusual size 

 and take on stronger colors, white flowers ac- 

 quiring a pink color, blue .ones a deeper tint, 

 and all receiving a tinge of red. No plant ex- 

 cept the mimosa was observed to contract its 

 leaves during the two months or longer that 

 the sun remained above the horizon. 



ELECTRIC LIGHTING. This method of 

 lighting seems now to have passed the purely 

 experimental stage, and to have become estab- 

 lished upon a secure commercial basis. For 

 the illumination of open areas and large in- 

 teriors, such as factories, railroad depots, thea- 

 tres, hotels, etc., the arc light is satisfactorily 

 displacing gas, both here and abroad. In Paris 

 and London the Jablochkotf candle has been 

 more largely used than any other lamp ; but in 

 this country the lamps of Brush, Maxim, Fuller, 

 and other American inventors are employed. 

 These lamps have all been described, and need 

 no further consideration; but in the first an 

 important improvement has been introduced, 

 which allows a number of them to be operated 

 upon one circuit, without any one being affected 

 by variations in any other. This consists in a 

 construction of the feed-regulating helices, so 

 that the current has two paths through the 

 lamp, one by way of the arc and one by way 

 of a resistance-coil. Each of the bobbins of the 

 controlling magnet is wound with two coils in 

 opposite directions, the primary one being of 

 thick and the secondary of thin wire. The 

 connections are such that the currents in the 

 two coils are in opposite directions, but these 

 latter are so related that when the arc is of nor- 

 mal length the attractive influence of the pri- 

 mary overcomes the opposing influence of the 

 secondary coil. The current flowing through 

 the high resistance secondary coil is ordinarily 

 not more than one per cent, of the total cur- 

 rent through the lamp; but when, by the length- 

 ening of the arc, the resistance is increased, a 

 greater part of the current goes through it, 

 with the effect of weakening the primary coil. 

 The cores of the bobbins then move downward 

 until the arc is of normal length. When this 

 becomes too short the resistance is diminished, 

 and a larger part of the current then flows 

 through the primary coil, which draws up its 

 core and raises the carbon. By this con- 

 struction the resistance of the lamp is ren- 

 dered constant, however much that of the arc 

 may vary, which is the sole condition neces- 

 sary to the successful operation of a number 

 of lamps on one circuit. Whenever a lamp, 

 from the entire consumption of the carbons, 

 or from any other cause, is -rendered unfit 

 to furnish light, it is cut from the circuit by 



a simple magnetic switch. In the same case 

 with the regulating bobbins an electro-mag- 

 net is placed, which is wound with two coils, 

 both in the same direction, the inner one be- 

 ing of low and the outer of high resistance. 

 The armature of this magnet is carried on the 

 end of a lever, and when it is drawn up in con- 

 tact with the pole the current has a path from 

 one terminal of the lamp, through the primary 

 coil of this magnet, through two contact points 

 then together, and through a resistance-spring 

 out to the other terminal. The secondary coil 

 is connected with the corresponding ones of 

 the regulating bobbins. Should the arc then 

 fail from any cause, u greater part of the cur- 

 rent circulates through the secondary coils, the 

 cut-out magnet is magnetized and draw's up its 

 armature, allowing the main current to flow 

 through the primary coil of this magnet and 

 out to line. Each of the remaining lamps be- 

 comes proportionately brighter, but, by mecns 

 of a simple instrument at the distributing cen- 

 ter, resistance-coils are automatically insert- 

 ed in the circuit, restoring their normal bril- 

 liancy. By these simple contrivances Mr. 

 Brush is enabled to operate any desired num- 

 ber of lamps from one machine with the same 

 ease as one, a necessary condition of any ex- 

 tended introduction of this light for indus- 

 trial use. The light-machines are built in dif- 

 ferent sizes, the standard operating sixteen 

 lights of two thousand candle-power each, and 

 absorbing fourteen horse-power. The largest 

 yet built maintains forty lights of the same 

 candle-power, and uses thirty-six horse-power. 

 Some five thousand of these lamps are now in 

 use in this country, and extensive preparations 

 have lately been made to introduce them in 

 London. The carbons used in the lamps are 

 twelve inches long and seven sixteenths of an 

 inch in diameter, one pair burning eight hours. 

 The lamps are also made with two sets of car- 

 bons, the current being switched to the second 

 when the first pair are consumed. The method 

 of doing this is simply an extension of the 

 feeding-device employed with the single car- 

 bons. The tilting washer by which the carbon- 

 holder is gripped and raised, is placed higher 

 on one carbon than the other. When the core 

 of the helix is drawn upward by the influence 

 of the current in starting the light, the carbon 

 with the higher washer is moved too great a 

 distance to form the arc, so that it is established 

 between the other two. This relation is main- 

 tained until the first pair of carbons are burned 

 out, when the current passes through the sec- 

 ond pair. 



The incandescent light has made steady 

 progress, and now appears to be in a fair 

 way of going into use at an early date. Mr. 

 Edison has finished his experimental work, 

 and is ready to enter upon the general in- 

 troduction of his system. The lamp in its 

 present form differs from that described in the 

 "Annual" of 1879, only in the employment 

 of a strip of carbonized bamboo instead of 



