508 ANNUAL EECOKD OF SCIENCE AND INDUSTRY. 



used for the electro-decomposition of metals ; with the best 

 machine hitherto known, moving with a velocity of twenty- 

 four thousand revolutions per minute, one hundred and 

 seventy grains of silver were deposited every hour; while 

 with a small Gramme machine, moving with a velocity of 

 three hundred revolutions, there were deposited two hundred 

 grains of silver. The electric light generated by a Gramme 

 machine has been exhibited on the tower of the Houses of 

 Parliament. The machine is worked by a small engine in 

 the basement of the building ; from the machine two coj^per 

 wires, half an mch in diameter, are led a distance of nearly 

 nine hundred feet upward to the signal. The light passes 

 through a lens twenty-one inches in diameter, and, by means 

 of the proper machinery, is made to sweep the horizon as in 

 the revolvino; lifvhts of a liojht-house. These liarhts are ex- 

 hibited during the sessions of Parliament. 



These machines prove themselves to be valuable, not only 

 for electric illumination, but also for chemical decomposition; 

 for military signaling; for the exploding of gunpowder; for 

 electro-plating ; for telegraphy ; and for medical purposes. 

 16 A 



NEW METHOD OF ILLUMINATION. 



A uniform, brilliant, white, but mild and agreeable light, 

 adapted to supplying the place of gas (in its mode of use, and 

 otherwise), where the latter is not to be had, or is difficult to 

 use, has recently been patented by Silber, and is in use on 

 some of the steamers of the Cunard, Inman, and other lines, 

 as well as on many of the English railroads. The peculiarity 

 is in the burner, which converts the oil into gas, and regulates 

 the access of air an^ gas so exactly that there is practically 

 no consumption of wick, no accumulation of impurities, and 

 no smoke. The apparatus varies in its details, according to 

 the nature of the oil employed (as rape-seed oil, light hydro- 

 carbons, etc.), but, in the main, consists of a series of concen- 

 tric, vertical double cylinders, inclosing each other, with 

 definite spaces between ; the interior space of the first cylin- 

 der furnishing air; the first cylinder containing the wick; 

 the second cylinder supplyirrg air to the outside of the wick ; 

 the third containing oil, and being in communication with the 

 reservoir as well as with the wick. The mouths of these 



