The cutter heads for tenoning machines have undergone many modifications; acting transversely to the grain of the wood, they form an exception to most other machines, and need what is known technically as "spurs " to sever the ends of the fibre before the shaving or cut is made. The cutters also require a kind of shearing action, that is now gained by setting their faces diagonal to the line of the spindle, in which case the faces are planes. At first they were sprung into a kind of curvelinear

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... form to accomplish the same end ; in fact some makers yet make them so in :England, which is the most to be wondered at when we consider that the effect is quite the same with the straight cutters, which can be made at a much less cost. Several articles appeared of late in this Journal relating to the use and abuse of steamboilers; the feed-water being a necessary component to it, allow me to make it the subject of this treatise. Often it may occur that several sources are at disposition from which to draw the water supply ; in such cases it is best to consider not only the cost of bringing the water to a certain point, but also the quality of the different waters, i. e. how much sediment each will leave on evaporatiou of equal quantities and what is the chemical composition of such residuum ? At first glance it will be admitted that two boilers of equal dimensions in every particular, of like setting and the same attendance, fired up simultaneously, will show quite a different evaporative power after say eight days service, when the feed-water supplied to the one, leaves for instance but one lb. of sediment for every 1000 gallons of water transferred into steam ; while that of the second boiler deposits two lbs. per 1000 gallons. In other words the boiler with the purer water will, after the eight days operation, require less coal per horse power per hour, than the other boiler; besides, the former will necessitate less stoppages for cleaning or blowing off, and remain a longer time in service before turning unsafe. But, as already stated, it is not merely the quantity of incrustation. :No ! also its quality, the chemical composition of the water asks for its share of attention ; because when one kind of water contains,