106 ANNUAL OF SCIENTIFIC DISCOVERY. 



building. It will plane a mass of iron 40 feet in length, 20 feet in 

 width, and 20 feet in height. One of the bed-pieces weighs over 

 40 tons. It is an elegant piece of workmanship, and reflects 

 great credit upon American skill. Among other new and expen- 

 sive tools in the machine-shop, there is also a boring-mill, which 

 will bore 12 feet in diameter, and will turn 24 feet in diameter. 



Recently, in the shop of the Boston Machine Company, on First 

 Street, South Boston, a gigantic slotting-machine was put in 

 motion for the first time. It is a ponderous piece of mechanism, 

 weighing a little over 60 tons, and was made for the government 

 machine-shop at the Charlestown Navy Yard. When removed 

 to its destination it will be placed next to the mammoth planer, 

 lately added to the Navy Yard works, and, like the planer, is the 

 largest machine of its class in the United States. It is intended 

 to perform the heavy slotting work on marine engines, is after an 

 improved plan, and possesses immense power. 



Differential Motion. — At a recent meeting of the Massachusetts 

 Institute of Technology, Mr. Henry F. Shaw, of Roxbury, exhib- 

 ited several models of machinery, in which differential motion is 

 applied with remarkable effects, obtaining by the use of two 

 wheels, of which the inner has an eccentric motion, as great a 

 result as by the ordinary train of several wheels. By varying the 

 excess of the number of teeth in the outer wheel, he obtains 

 different velocity as required. In addition to the simplicity of 

 this arrangement, as several teeth of the wheels are always in 

 contact, there can be no retrograde motion unless by the same 

 slow process by which the forward motion is produced ; there can 

 be no slipping, however great the load, the apparatus being self- 

 sustaining. He exhibited his invention as applied to a windlass, 

 elevator, pulley, lathe, planing machine, and ship-steering appar- 

 atus. 



Manufacture of Steel. — At a recent conversazione of the London 

 Institute of Civil Engineers, a process for manufacturing steel by 

 friction was explained. By the aid of machinery, pig iron is 

 ground to powder by a rapidly moving cutter. The great amount 

 of friction generated produces a heat so intense that the iron is 

 set on fire, and, after scintillating, falls down as reddish-brown 

 dust, the combustion having caused the riddance of the super- 

 fluous carbon. The dust is collected, put in a crucible, melted, 

 and when cooled, is found to form ingots of steel of superior 

 quality. 



Large Chilled Boll. — At Pittsburgh, Pa., has recently been cast 

 a chilled roll, by Messrs. Bollman, Boyd, & Bagaley, of a diameter 

 of 28 inches. This is by far the largest chillecl roll yet made. It 

 is to be used in rolling copper. 



Large Armor Plate. — An armor plate has been made at Sheffield, 

 England, which was, before rolling, 20 feet long, 4 feet broad, 

 and 21 inches thick, weighing 420 cvvt. The final rolling reduced 

 the thickness to 15 inches. Two hundred and fifty tons of coal 

 were consumed, and the labor of 200 men required for its pro- 

 duction. 



