BLOCK MANUFACTURE 



399 



pressed ; in liko manner, the other pair is attached to the lower part of the saw-frame, 

 so that the saw can bo moved sidewise by moans of their handles, which theii swing 

 the saw from its vortical position. 



These two handles give the attendant a complete command of the saw, which we 

 suppose to bo in rapid motion, the tree being brought forward and properly fixed. By 

 one handle, he draws the saw against one side of the tree, which is thus cut into (per- 

 haps half through) ; now, by the other handle, he raises the saw up, and by the first- 

 mentioned handle he draws it across the top of the tree, and cuts it half through from 

 the upper side ; he then depresses the saw and cuts half through the next side ; and 

 lastly a trifling cut of the saw, at the lower side, completely divides the tree, which is 

 then advanced to take another cut. 



The great reciprocating saw is on the same principle as the saw-mill in common use 

 in America. 



3. The circular ripping saw is a thin circular plate of steel, with teeth similar to 

 those of a pit saw, formed in its periphery. It is fixed to a spindle placed horizontally, 

 at a small distance beneath the surface of a bench or table, so that the saw projects 

 a few inches above the bench through a crevice. The spindle being supported in 

 proper collars has a rapid rotatory motion communicated to it by a pulley on the oppo- 

 site end, round which an endless strap is passed from a drum placed overhead in the mill. 

 The block cut by the preceding machine from the end of the tree is placed with one 

 of the sides flat upon the bench, and thus slides forward against the revolving saw, 

 which cuts the wood with a rapidity incredible to any one who has not seen these or 

 similar machines. 



4. Boring-machine. The blocks prepared by the foregoing saws are placed in the 

 machine represented in Jig. 140. This machine has an iron frame, A A, with three 

 legs, beneath which the block is introduced, and the screw near B being forced down 

 upon it, confines it precisely in the proper spot to receive the borers D and E. This 

 spot is determined by a piece of metal fixed perpendicularly just beneath the point of 

 the borer E, shown separately on the ground at x ; this piece of metal adjusts the 

 position for the borer D, and its height is regulated by resting on the head of the 

 screw x, which fastens the piece x down to the frame. The sides of the block are 



140 



141 



kept in a parallel position, by being applied against the heads of throe screws tapped 

 into the double leg of the frame A. The borer D is adapted to bore the hole for the 



