8

MANUFACTURES.

Manu-

factures.

Packing andtransport ofcotton.

which rends it in a still shorter time. If the circumstances are favourable, and the sect. i.workman skilful, the time and expense may be still further reduced by the use of a ' vsmall quantity of gunpowder exploded in holes judiciously placed in the block.

When a mass of matter is moved a certain force must be expended, and upon theproper economy of this the price of transport depends. A Country must, however, havereached a high degree of civilisation before it will have approached this limit. Thecotton of Java is carried in junks to the coast of China , but from the circumstance of theseed not being previously separated, three quarters of the weight is not cotton. Thismight, perhaps, be justified by the want of Machinery to separate it in Java , or by therelative cost of the operation in the two Countries. But the cotton itself, as packedby the Chinese , occupies three times the bulk of an equal quantity shipped by Euro-peans for their own markets. Thus the freight of a given quantity of cotton costs theChinese nearly twelve times the price to which, by a proper attention to Mechanicalmethods, it might be reduced.*

We shall now offer to our readers a general view of the various advantages whichresult from the use of Machinery .

I. OF ACCUMULATING POWER.

Whenever the work to be done requires more force for its execution than can begenerated in the time necessary for its completion, recourse must be had to someMechanical method of preserving and condensing a part of the power exerted previouslyto the commencement of the process. This is most frequently accomplished by a fly-wheel, which is in fact nothing more than a wheel having a very heavy rim, so thatthe greater part of its weight is near the circumference. It requires great power appliedfor some time to set this in rapid motion, and when moving with considerable velocity,Fiy neces- if its force is concentrated on a point, its effects are exceedingly powerful. In some ofrolling iron, the iron- works, where the power of the steam-engine is a little too small for the rollerswhich it drives, it is usual to set it at work a short time before the red-hot iron isready to be removed from the furnace to the rollers, and to allow it to work with greatrapidity until the fly has acquired a velocity rather alarming to those unused to suchestablishments. On passing the softened mass of iron through the first groove, the enginereceives a great and very perceptible check, and its speed is diminished at the next andat each succeeding passage, until the iron bar is reduced to such a size that theordinary power of the engine is sufficient to roll it.

A i s „ in The powerful effect of a large fly-wheel when its force can be concentrated in a point,pklfiron. was curiously illustrated at one of the largest of our Manufactories of steam-engines. Theproprietor was showing to a friend the method of punching holes in iron plates forthe boilers of steam-engines. He held in his hand a piece of sheet iron three-eighthsof an inch thick, which he placed under the punch; observing, after several holes hadbeen made, that the punch made its perforations more and more slowly, he called to the

* Crawford's Indian Ai nhipelago.