410 



ELECTRICITY. 



remaining source of interruption is the presence 

 of silica or metallic residua as impurities in the 

 carbons. Thus, when these have wasted to a 

 point at which iron or antimony occurs, there 

 is a slight change of color and momentary 

 flicker, but which are of no practical conse- 

 quence. In the new arrangement, the attend- 

 ant of the steam engine can learn in a few 

 hours all that requires to be looked after. The 

 electric light does not, like the oil lights, neces- 

 sitate an interruption for trimming, a process 

 that with the latter must be performed at least 

 as often as once during each night. The actual 

 expense of the former still remains somewhat 

 the greater ; but if its increased intensity and 

 penetrative power be taken into the account, it 

 is really the cheaper; and the qualities just 

 named can be greatly augmented at a slightly 

 increased ratio of expense. 



Serrirfs Electric Light Regulator. Those 

 specially interested in the subject of electric 

 lights may be referred to an account of the 

 principle of operation of the regulator for such 

 lights devised by M. Serrin, originally ap- 

 pearing in the Comptes Rendus, and quoted in 

 the "Journal of the Franklin Institute," Dec. 

 1862. Briefly, the method is that of holding 

 the carbon points very near to each other by 

 means of springs, but preventing the bringing 

 of the points into positive contact so as pos- 

 sibly to interrupt the light, by so disposing in 

 the apparatus or regulator containing the 

 points an electro-magnet, the armature of 

 which falls as often as the circuit is in such 

 manner completed, that the weight of this ar- 

 mature just overbalances the tension of the 

 lower springs sufficiently to depress the lower 

 carbon to a very slight extent. 



Baker's Apparatus for Electric Lights. Mr. 

 A. L. Fleury exhibited at a meeting of the 

 Franklin Institute, April 17, 1862, a magneto- 

 electric machine, and also a mechanism for 

 electric lights, the inventions of Mr. H. N. 

 Baker, and constructed by Messrs. Collier and 

 Co., of Binghampton, N. Y. The mechanism 

 for controlling the relative positions of the 

 carbon points is extremely simple. The car- 

 bons are in form of long cones or pencils, and 

 placed vertically, one over the other. A hole 

 in an upper metallic strap or bridge, is of such 

 size that the carbon pencil sinks only to a cer- 

 tain depth in it ; while a hole in a lower strap 

 is large enough to allow the lower pencil to 

 rise freely through it. While the current is 

 passing, as U usual, particles are carried off 

 from the positive carbon electrode and deposit- 

 ed on the negative one. Thus, the former 

 wastes, and the latter may be injured by be- 

 coming blunt or coated with irregular deposit. 

 To prevent the unlike effect on the two pencils, 

 Mr. Baker resorts to the French system of con- 

 tinually reversing the current; and the waste 

 of both pencils thus becomes similar. Now, 

 the lower pencil being placed as a float (though 

 on what liquid the account does not state), it 

 results that, as the gradual waste goes on, the 



upper pencil is simply fed downward continual- 

 ly by its gravity, while the lower one is just as 

 regularly fed upward by its buoyancy. This 

 is the arrangement when a current of large 

 " quantity" and low intensity is employed, the 

 electrodes being in such case satisfactorily ignit- 

 ed although they continue in actual contact. 

 When, however, a current of high intensity is 

 employed, the pencils are allowed only to ap- 

 proach very close, but without touching ; and 

 to accomplish this, the hole in the lower strap 

 is also made so small as to admit a certain 

 length only of the pencil. It would appear 

 that the apparatus operates successfully on the 

 scale on which it has been tried, or as an elec- 

 tric lamp ; and it is said to be extremely cheap. 

 ("Jour. Fr. Inst.," May, 1862.) 



The Present Desideratum in Electric Lights. 

 The magneto-electric light, which is prob- 

 ably the most economical in use, has still the 

 disadvantage of the great waste of power ne- 

 cessarily attending the successive transforma- 

 tions of a given amount of force. In producing 

 this light, the heat developed by the combus- 

 tion of coal is converted, first, into mechanical 

 power; the mechanical power must then be 

 transformed into electricity, and this finally 

 into a heat which shall result in light. Now, 

 M. Joule has shown that in the first of these 

 transformations, even when effected under fa- 

 vorable circumstances, no more than -^ part of 

 the heat is actually realized in mechanical 

 power, y 9 ^ of the force developed from the 

 coal being lost. This loss of power, and of 

 useful effect, is strikingly illustrated in the 

 case of the English and the French ice-making 

 machines in the Exhibition of 1862. These 

 machines alike derive their capacity of pro- 

 ducing ice from the combustion of coal. But 

 while, in the English machine, the heat of the 

 coal is first converted into the mechanical 

 power of a steam engine, and the product is 

 but two tons of ice per ton of coal consumed, 

 in the French machine this preliminary trans- 

 formation of the heat through the driving of an 

 engine is dispensed with, and the product is 

 declared to be from 10 to 13 tons of ice for 

 each ton of coal burned in the furnace of the 

 apparatus. These considerations indicate the 

 direction in- which the improvement (in econo- 

 my) of the electric light should be sought. 

 The object aimed at should be that of trans- 

 forming, as directly as possible, the heat gen- 

 erated by combustion of coal into electric cur- 

 rent-force. It is remarked by Dr. Frankland, 

 from whose account of " Illumination" in the 

 "Record of the Great Exhibition, 1862," these 

 thoughts are drawn, that the researches of Dr. 

 Matthiessen on the thermo-electric properties 

 of tellurium promise important results in the 

 direction here indicated. 



Electric Light Signals. The electric light, 

 in whatever mode produced, admits of being 

 instantaneously extinguished and as quickly re- 

 lighted. Hence, it can be made at will to shine 

 or disappear; and a system of signals with 



