ELECTRIC LIGHTING, PROGRESS OF. 



EMERSON, RALPH W. 277 



6. Mechanical Energy. Since an absolute 

 unit of work is done per second by an absolute 

 unit of electro- motive force in a circuit of one 

 absolute unit of resistance, 1 volt-ampere rep- 

 resents 10 7 absolute units of mechanical work 

 per second, or 0*10192 kilogramme-metres. 

 By multiplying the volt-amperes by 0.10192, 

 the product is the mechanical work done in 

 the lamp in kilogramme-metres. 



7. Lamps per Horse-power of Current.* 

 One horse-power is 75 kilogramme-metres per 

 second. By dividing 75, therefore, by the num- 

 ber of kilogramme-metres of work done in the 

 lamp per second, the quotient:is the number of 

 such lamps maintained by a horse-power of 

 current. 



8. Candles per Horse-power of Current. 

 The number of candle-lights per horse-power 

 of current is obtained, of course, by multiply- 

 ing the number of lamps per horse-power of 

 current by the corrected candle-power of each. 



9. Normal Lamps per Horse-power of Cur- 

 rent. Conversely, by dividing the number of 

 candles per horse-power of current by the nor- 

 mal value of the lamp in standard candles (in 

 the present case 16 or 32), the number of nor- 

 mal lamps per horse-power of current is ob- 

 tained. 



SUMMAET OF RESULTS. 



(a.) At 16 Candles. 



(6.) At 32 Candles. 



VI. CONCLUSIONS. The following conclu- 

 sions seem to be sustained by the results which 

 have now been given : 



1. The maximum efficiency of incandescent 

 lamps in the present state of the subject, and 

 within the experimental limits of this investi- 

 gation, can not be assumed to exceed 300 

 candle-lights per horse-power of current. 



* This is the French horse-power, cheval-vapeur = 542$ 

 foot-pounds per second, as stated abore. instead of 550 foot- 

 pounds. 



2. The economy of all lamps of this kind is 

 greater at high than at low incandescence. 



3. The economy of light-production is greater 

 in high-resistance lamps than in those of low 

 resistance, thus agreeing with the economy of 

 distribution. 



4. The relative efficiency of the four lamps 

 examined, expressed in carcel-burners of 7*4 

 spermaceti-candles each, produced by one horse- 

 power of current, is as follows: (A.) At 16 

 candles: Edison, 26-5; Swan, 24; Lane-Fox, 

 23-5; and Maxim, 20'4. (B.) At 32 candles: 

 Edison, 41-5; Lane-Fox, 37*4; Swan, 35'5 ; 

 and Maxim, 32-4. To double the light given 

 by these lamps the current-energy was in- 

 creased, for the Maxim and Lane-Fox lamps, 

 26 per cent ; for the Edison lamp, 28 per cent ; 

 and for the Swan lamp, 37 per cent. 



EMERSON, RALPH WALDO. Born in Bos- 

 ton, Mass., May 25, 1803. His father, Will- 

 iam Emerson, was pastor of the First (Uni- 

 tarian) Church in that city, and his grandfather 

 also was a preacher. In his eighth year, on 

 the death of his father, he was sent to the 

 Grammar School, and was fitted for college at 

 the Boston Latin School. He entered Harvard 

 College in 1817, in his fourteenth year, and 

 was graduated in 1821, having had among his 

 instructors Edward Everett, George Ticknor, 

 and Caleb Cushing. He was not at all dis- 

 tinguished as a student, though he succeeded 

 in carrying off prizes for dissertations and 

 declamation, and was noted as a frequenter of 

 the library and for knowledge of general liter- 

 ature. He was also the poet of his class on 

 "class-day." The five years following his 

 graduation were spent in teaching school. 



As it was expected that Emerson should fol- 

 low the family tendency to preaching, he studied 

 divinity, chiefly under Channing, and was " ap- 

 probated to preach," in 1826, by the Middlesex 

 Association of Ministers; but, owing to general 

 debility, he did not enter upon public work for 

 some time. In March, 1829, he was ordained 

 as colleague of Henry Ware, at the Second 

 (Unitarian) Church of Boston, and in a year's 

 time became sole pastor. This kind of labor, 

 however, does not appear to have been quite 

 congenial, and as his peculiar cast of mind led 

 him to entertain and express grave doubts as 

 to the sacrament of the Lord's Supper being a 

 permanent institution, or of any value to any 

 one in these latter days, he first brought the sub- 

 ject before his congregation, and urged substitu- 

 tion of some other rite of commemoration ; and 

 when the people to a man refused to adopt his 

 views, he quietly resigned, in 1832, and retired 

 from any further connection with public preach- 

 ing. Thenceforward he turned his attention 

 largely to giving lectures, and writing in both 

 poetry and prose. He traveled in Italy, France, 

 and England, for a year. While in England 

 he visited Wordsworth, Coleridge, and Carlyle, 

 with the last of whom he formed a close friend- 

 ship, despite Carl yle's cynicism and fixed habit 

 of abusing his fellow-men, which was in marked 



