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The cutters revolve in opposite directions, and the work may he pressed against either one or the other, so as to suit the cut to the direction of the grain of the wood, without the workman having the trouble of reversing its position.

33. Agricultural Implements—Ploughs.—Labour-saving machines are most successfully employed in the manufacture of agricultural implements.

In a plough manufactory at Baltimore eight machines are employed on the various parts of the woodwork.

With these machines seven men are able to make the wooden parts of thirty ploughs per day.

The handle pieces are shaped by a circular cutter, having four blades, similar to those of smoothing planes, fixed on a horizontal axis, with about two inches radius, and making nearly 4,000 revolutions per minute. The work to be shaped is fastened to a pattern, which is pressed against a loose roller on the axis of the cutter as the workman passes it along, and it is thus cut of exactly the same shape as the pattern.

All the ploughs of a given size are made to the same model, and their parts, undergoing similar operations, are made all alike. Some of the sharp edges of the wood are taken off or