ELECTRIC LIGHT, EDISON'S. 



ENGINEERING. 



Tho generating machine devised by Edison 

 consists of a magnet composed of two upright 

 iron columns, three feet and eight incnes in 

 height, wound with coarse wire and resting 

 upon blocks, which form the magnetic polo-. 

 Tnese are made in such a way as to nearly in- 

 close a wooden armature of cylindrical form, 

 wound lengthwise with coarse wire, which 

 is revolved on Its axis with great rapidity be- 

 tween the poles of the magnet, which nearly 

 . clasp it about. Springs resting upon a metal- 

 lic portion of the revolving cylinder convey to 

 the conducting wires the electricity which is 

 generated in the wires, which run around the 

 wooden cylinder parallel to its axis. 



The system adopted by Edison dates from 

 an invention patented by Edward A. King of 

 London, for obtaining a light from the incan- 

 descence of either platinum or carbon. It had 

 before been observed that a thin wire inter- 

 posed in an electrical current became heated, 

 and that the heat generated was proportionate 

 to the degree of resistance of the metal. Chil- 

 dren showed that an electric current passed 

 through a chain composed of silver and plati- 

 num in alternate links, caused the metal of low 

 conductivity to be heated to a bright glow, 

 while the silver links remained dark and cool. 

 King's attempt to utilize this property of sub- 

 stances of high electrical resistance was with 

 a strip of platinum leaf or piece of carbon held 

 between conductors, and rendered luminous by 

 a properly regulated current within a glass 

 globe which protected the incandescent sub- 

 stance from air-currents. In 1849 Petrie ob- 

 tained a fine light from the incandescence of 

 iridium or one of its alloys. In Lodyguine's 

 lamp, in which the light was obtained from 

 carbon rendered incandescent in vacua, one 

 part of the carbon rod was made thinner than 

 the rest ; and the thin portion was that which 

 became incandescent, as the electrical resis- 

 /ince was greater here than elsewhere. This 

 tenewed attempt to obtain a practical light by 

 incandescence was made long after the labors 

 if King and the other preceding inventors 

 were forgotten, and obtained for Lodyguine 

 ihe Lomonosoff prize from the St. Peters- 

 burg Academy of Sciences. Konn of St. Pe- 

 tersburg devised and patented, in 1875, a lamp 

 in which several carbon rods were held in re- 

 serve to replace the incandescent rods auto- 

 matically as they were consumed. Even in 

 an exhausted chamber it was found that the 

 carbon wasted away. Another Russian invent- 

 or, Bouliguine, devised a lamp in which a sin- 

 gle rod of carbon was used ; it was made of 

 great length, and the lamp was so constructed 

 that this rod was pushed gradually upward 

 through a tubular holder, the portion exposed 

 at the top of the tube alone becoming incan- 

 descent, as this part was firmly held between 

 conical jaws of carbon which allowed a free 

 passage to the electricity. 



The form of carbon used in Sir Humphry 

 Davy's electric light was ordinary wood-char- 



coal. In 1844 Leon Foucault substituted that 

 variety of carbonaceous matter which is de- 

 posited in the interior of gas-retorts, and which 

 bears the name of gas-graphite. It is produced 

 by the decomposition of dense hydrocarbons 

 at a very high temperature. It is deposited in 

 layers on the walls of the retorts during the 

 manufacture of coal-gas. It is of a very hard 

 texture, and when sawn into rods or pencils is 

 better adapted to electric lighting than the less 

 dense forms of carbon, like wood-charcoal, be- 

 ing much more durable. It has, however, some 

 serious defects. It varies in its compactness 

 and texture, and with the variations in its den- 

 sity the light obtained from it fluctuates in 

 brightness. Many have attempted before Edi- 

 son to obtain a carbon of a more perfectly ho- 

 mogeneous texture. Carre and Gaudoin in 

 France have attained a tolerable degree of suc- 

 cess in producing carbon of greater homoge- 

 neity by artificial processes. 



ENGELHARD, JOSEPH ADOLPHTS, was born 

 at Monticello, Mississippi, September 27, 1832, 

 and died at Raleigh, North Carolina, February 

 17, 1879. His school-days were spent in Mis- 

 sissippi and New Albany, Indiana (principally 

 at the latter place), whence he went to Chapel 

 Hill, North Carolina, in 1850, and graduated 

 in 1854. He studied law first at Harvard, then 

 at Chapel Hill, under Judge Battle, afterward 

 with Judge Fowle, and was licensed to prac- 

 tice in the County Courts in 1856, and in the 

 Superior Courts in 1857, locating in Tarboro, 

 where he remained until the breaking out of 

 the war. In May, 1861, he entered the mili- 

 tary service of the State as captain and quar- 4 

 termaster of the 33d regiment. In April, 1862,' 

 he was promoted to be major and quartermas- 

 ter of the brigade of General Branch, and in 

 December of that year was transferred to Gen- 

 eral Fender's brigade as its adjutant-general. 

 In May, 1863, he became the adjutant-general 

 of Fender's division, afterward Wilcox's divis- 

 ion, in which capacity he remained until the 

 surrender at Appomattox Court House. In 

 1865 he became interested in the "Wilmington 

 Journal," and its editor. In recognition of his 

 services in this position his party nominated 

 him for Secretary of State at the last election. 

 He was elected, and in discharge of the duties 

 of the office at the commencement of his fatal 

 sickness. 



ENGINEERING. If one half of the great 

 engineering undertakings which are now seri- 

 ously proposed, and demonstrated by more or 

 less exact calculations to be feasible, were, by 

 a happy unanimity of private and national will 

 and action, to be carried into effect, then for a 

 generation or two to come all the labor and 

 productive energy of civilized nations would 

 find full scope and employment, and changes 

 would be wrought in the face of nature of 

 greater magnitude than all the physical trans- 

 formations which human skill has accomplished 

 from the beginning of man's life on the planet. 

 There must be a great future for an art whose 



