MECHANICS AND USEFUL ARTS. 67 



with unfailing precision. A hole is also drilled in one side of the barrel, in 

 which to fasten the opposite end of the spring. 



The barrel is now taken from the lathe and placed upon another machine 

 to have its teeth cut. This operation is performed by a minute chisel revolv- 

 ing upon a cylinder at high speed, the machine automatically moving the 

 piece in a circle so as successfully to present every part of its edge to the 

 cutter, until the entire number of sixty teeth are formed. The teeth of the 

 wheels are cut upon the same principle, although of the smaller sizes from 

 forty to sixty wheels are placed upon the machine at once, and operated 

 upon by the same motion. In another part of this room all the pivots of 

 steel and the shoulders of pinions are cut to their proper size by machinery. 

 Pinions are the axles of wheels, and pivots the bearing ends on which they 

 run. Some of these are very small, and parts of them so slender that they 

 can hardly be manipulated without injury from accidental pressure; never- 

 theless, machinery strong enough to gouge out metal chips without apparent 

 effort, grasps these diminutive pieces with equal delicacy and firmness, re- 

 leasing them at last in perfect form and safety. The teeth of these wheels, 

 located at and near the centre of the pinions, are drawn out from the wire by 

 one machine, and are then passed under another which opens them to the 

 precise angle required, and polishes away all superfluous metal, reducing 

 them instantaneously, almost to the exact proportion desired. 



The escape-wheels are cut by a machine somewhat similar to that perform- 

 ing the dental operation already described. In no part of the mechanism is 

 the perfection of the machinery put to a severer test than here, for the escape 

 must be shaped by it with absolute perfection, as no tool can be applied 

 thereto subsequently. Sixteen of the blanks are put upon the lathe at the 

 same time, and then by three distinct motions all accomplished in less than 

 one minute the eccentrically-shaped teeth are cut, and the wheels come out 

 the most exquisitely-delicate little affairs imaginable. Another machine 

 rapidly turns out pillars of brass each with several minute flanges used 

 in fastening the large plates of the watch to each other. Others make the 

 various screws required for putting the movement together. Some of these 

 are so minute, that ninety-five thousand of them weigh only a single pound ! 

 The steel wire of which this number is made costs originally on^v a do!l ir, 

 worth, when thus manufactured, nine hundred and fifty dollars ; the labor there- 

 upon multiplying the value of the raw material nine hundred and fifty ti/iK.s! 

 A piece of the wire being placed in the machine, is seized firmly and carried 

 forward to a position where a tool meets and points it. This done, another 

 tool advances, cuts it down to a required size, at the same time forming 

 the shoulder, and retires. A third tool promptly follows up the work by 

 cutting the thread upon the screw, and a fourth nearly severs it from the 

 wire. The operative now picks up from his bench a sort of rack of steel, 

 perforated with holes, in which the screw fits easily, and, inserting the 

 screw-point into one of these, breaks it off above the head, repeating the 

 operation until the rack is full. The rack now presents to view a long 

 straight row of screw-heads still needing the groove into which the screw- 

 driver is to be inserted when forcing them home. This is promptly supplied 

 by passing the rack horizontally under another instrument which cuts the 

 groove, and, when " case screws " are wanted, saws off a segment of the 

 head at the same time. 



A little further on we find machinery for turning the brass plates both 

 large and small. Each, piece is perfected in an instant. By similar means 



