10-14
TIIEOKY AND PRACTICE OF ENGINEERING.
Book II.
The fifteenth are the hammers, put in rapid motion by the machinery, for rivetingthe pins which hold the gun metal coaks into the cavity in the sheaves.
The sixteenth is the broaching engine, where the sheave is fixed to a vertical revolvingaxis, and the borer is brought down into the hole in the centre of the coaked sheave, andbroached out to a perfect cylinder.
The seventeenth is the turning lathe, provided with a slide rest to support the turningtool, by which the sheaves are faced. Thus the blocks, shells, and sheaves are com-pleted.
The eighteenth is a turning lathe, with a slide rest to form the iron pins.
The nineteenth is a polishing engine, in which the pin is fixed into the lower end of avertical revolving axis, and forced down into a die immersed in oil, holding three pieces ofhard steel, between which the pin is pressed as it turns, and becomes completelypolished.
The twentieth apparatus is for boring large holes in any position, and is mostly used forblocks that are 50 inches or more in length, and have four sheaves.
'Die twenty-first is the machine for making dead eyes.
By this machinery 1420 blocks are perfected in one day, and it is not too much toobserve that the entire contrivances seem to embrace all the useful purposes that arerequired throughout the entire range of the mechanical arts. In the Edinburgh Encyclo-pedia, conducted by Dr. David Brewster , are most perfect and beautiful representations ofthese machines.
Saw Mills for cutting Marble: the frame is suspended by rods, in such a manner that afree horizontal reciprocating motion is given to it; the saw frame is attached to a cast-iron
Fig.1604.
ELEVATION OF MARBLE SAW MILIm
Fig. 1605.