120 ANNUAL OF SCIENTIFIC DISCOVERY. 



rapidity and ease of the ordinary saws, and yet leaving a nearly perfect 

 planed surface. It is a trifle thinner, requires little "set," and consequently 

 makes a thinner " kerf," or takes away less of the wood in cutting, than the 

 ordinary varieties. 



Saws are usually set by bending the alternate teeth laterally in opposite 

 directions ; no such set is put hi this saw. The general outline of the teeth 

 is that known as the "gullet," or "brier," and the peculiarity consists in 

 hollowing out or grooving the cutting face of every tooth, or of every alter- 

 nate one, in a line extending from the point inward. This form enables the 

 tooth to act as a gouge so as to cut smoothly rather than to tear away the 

 material, and by slightly spreading the acute edges at each side, a sufficient 

 width of kerf is attained to relieve the body of the saw. The grooves are 

 formed and renewed by clamping a small steel cutter-wheel upon the tooth 

 and turning it by a crank attached. The edges are spread by a blow or two 

 transmitted through a steel set or punch of suitable shape, and the sides are 

 " erased " or smoothed in the usual manner by touching lightly with a stone 

 while running. 



Previous attempts to widen the points of saw teeth have generally 

 failed, we think, from the teeth anchoring in the wood. The gouging pro- 

 pensity, or rather the clean cutting action due to the peculiar form, seems 

 to prevent any such evil, and if the thin edges can be made to endure, the 

 improvement will probably come into great favor. 



Attends Variable Feed for Sawmills. Soft wood nnay be fed up to a saw 

 much faster than hard, and there are in most logs inequalities which call for 

 different rates of feed every few seconds. Common sawmills can only be 

 adjusted so that the feed shall be moderate enough for the hardest knots, and 

 consequently too slow for the clear portions of the wood. Mr. Z. G. Allen, of 

 Buffalo, has lately invented a variable feed, of which the variation in the rate 

 is produced by allowing one wheel to turn by the friction alone or "rolling 

 contact" with the face or side of another, and letting the first move endwise 

 on its shaft at the will of the sawyer. By this means (the face- wheel being 

 on the end of its shaft, and supposed to revolve with any uniform velocity), 

 the number of turns per minute of the driven shaft varies with every new 

 position of the movable wheel. If its periphery is allowed to press against 

 the centre only of the face- wheel, no motion results ; but when moved ever so 

 little from that position, a degree of speed is obtained which increases with 

 every successive removal of the wheel from the centre, until, at its periphery, 

 the fastest rate of speed is attained. By means of a suitable lever held in the 

 hand of the sawyer, the rate at which the log is fed up may be varied with 

 every indication (by sound or otherwise) of a changing character in the wood. 

 The periphery of the driven wheel in this feed is made of hard wood, placed 

 in such manner that the end of the grain is always presented to rub against 

 the face- wheel. 



Barlow's Patent Circular Saw. This improvement consists in grooving the 

 faces of the saw teeth from their points inwardly, forming thereby acute 

 cutting edges or double fleams at their sides. Thus constructed the teeth act 

 upon the wood like so many gouges, cutting their way through, not tearing 



