284 



SCIENCE. 



[Vol. XII. No. 306 



THE EDISON LIGHT FOR HOUSES, STORES, THEA- 

 TRES, ETC. 

 There is probably no new industry of equal magnitude that is 

 comparatively so little known to the general public, even in this 

 city, as that of supplying the Edison incandescent light from cen- 

 tral stations for interior illumination. Six years ago a small sta- 

 tion was started at 255 and 257 Pearl Street. This station has 

 been running continuously, night and day, since Sept. 4. 1882, and 

 is now supplying some 15,000 lamps through a network of 56 miles 



of underground conductors. It was freely predicted that mechani- 

 cal and electrical difficulties would constitute a barrier to its suc- 

 cess ; but, these apparently insurmountable obstacles having been 

 overcome by the indomitable perseverance and peerless skill of Mr. 

 Edison, the next prognostication was financial failure. In spite of 

 these dire forebodings, the enterprise was long ago established 

 upon a successful paying commercial basis, as a result of which 

 the capitalists who were pioneers in the business have recently sup- 

 plied the capital with which to construct two immense stations for 

 supplying residences, stores, theatres, hotels, etc., in the upper por- 

 tion of the city. 



About 165 miles of conductors were laid under ground, covering 

 a district from i8th to 59th Streets, and from Sixth to Fourth Ave- 

 nues ; and two substantial buildings were erected, — one on 39th , 

 Street, near Broadway; and one on 26th Street, near Sixth Avenue. 

 These stations are about completed, and ready to furnish lights, 

 and will have an ultimate capacity of 50.000 lamps each. This 

 great luxury, so long enjoyed by many business-men in their down- 

 town offices, will now be within reach of their uptown homes, and 

 our citizens will welcome a light which does not heat or vitiate the 

 atmosphere by burning up the oxygen ; does not destroy or deteri- 

 orate decorations, pictures, books, etc.; obviates risk of fire ; is as 

 conducive to the preservation of eyesight as the natural light of the 

 sun ; and is capable of innumerable applications for ornamental and 

 decorative purposes, as well as for the supplying of power for 

 pumps, elevators, ventilating-fans, sewing-machines. For these 

 and many other purposes the electric current will be ever present, 

 night and day, and will be furnished and charged for by a meter 

 the accuracy of which has been proved by six years of practical 

 use, and at prices that will place one of the greatest luxuries of 

 modern times within reach of all. 



HADFIELD'S MANGANESE STEEL." 



The most notable contribution to the metallurgy of manganese 

 and its alloys made in recent years is the paper read before the In- 

 stitution of Civil Engineers of Great Britain by Mr. Robert A. Had- 

 field, of Hadfield's Steel Foundry Company, Sheffield, on Manga- 

 nese steel, the invention of his father, but which the author of the 

 paper has done so much to perfect. This steel has been described 

 in previous reports, but Mr. Hadfield's paper sets forth so clearly 

 some of the very peculiar properties that manganese in large quan- 

 tities imparts to steel, that, with his permission, we quote from it at 

 considerable length. 



The most noticeable characteristics of the Hadfield manganese 

 steel are its peculiar hardness, combined with great toughness, the 

 effect of water-quenching upon the steel, and its electrical proper- 

 ties. 



Peculiar Hardness. 



It is difficult to accurately describe its peculiar hardness, because 

 all the specimens are exceedingly hard ; in fact, it is scarcely possi- 

 ble to machine any of them on a practical scale, yet such hardness 

 varies considerably in degree, being most intense in the cast mate- 

 rial, containing 5 to 6 per cent manganese, which no tool will face 

 or touch. A gradual decrease is noted then, and, when about 10 

 per cent is reached, the softest condition occurs. Then an increase 

 again takes place, and at 22 per cent it is very hard, still not so 

 much so as in the 5 per cent. After passing 22 per cent, the cause 

 of hardness becomes more complicated, owing to the presence of 

 more carbon, 2 per cent and upwards ; in fact, the material begins 

 to partake more of the nature di cast iron, though as to strength, 

 when compared with the latter, specimen No. 225 (carbon, 2 per 

 cent ; manganese, 23.5 per cent) had a transverse strength of 34 

 tons against 10 tons for cast iron. 



The 8 to 20 per cent material can be machined, although only 

 with the utmost difficulty, as will be seen from the following exam- 

 ple. The test-bar No. 22 B (manganese. 14 per cent), which elon- 

 gated 44.5 per cent without fracture and had a tensile strength of 

 67 tons, was put under a double-geared 18-inch drill. Over an 

 hour was occupied in drilling one hole one half-inch in diameter by 

 three-fourths inch deep ; and even to do this it was requisite to run 

 at the lowest speed, or the edge of the drill would have given way. 

 During this time fifteen to twenty holes of the same size could have 

 been easily drilled in mild steel. Similar results from specimens 

 sent to different engineering firms in Sheffield and elsewhere con- 

 firm this test, yet this specimen could be indented by an ordinary 

 hand-hammer ; so that, whilst so hard, it may be said to possess 

 " a special kind of softness." Although, when being turned, it ap- 

 pears harder than chilled iron, its softness is particularly notice- 

 able when testing the material for compression. Specimens of 10- 

 per-cent manganese steel i inch long by .79 inch in diameter, 



^ Extract from a paper on ' Manganese,' by Joseph D. Weeks, to appear in the 

 forthcoming volume of ' Mineral Resources of the United States,' published by the 

 United States Geological Survey, edited by Dr. W. T. Day. 



