MECHANICS.

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Chap. 2.]

2. The power is to the weight, as the distance theweight moves, is to the distance the power moves, re-spectively.

That is, the power multiplied into its distance moved,is equal to the weight multiplied into its distance moved.

3. The power is to the weight, as the perpendicularascent of the weight, is to the perpendicular descent ofthe power.

That is, the power multiplied into its perpendiculardescent, is equal to the weight multiplied into its per-pendicular ascent.

4. Their velocities are as their distances from theircentre of motion, by the 3d law of circular motion, p. 28.

These simple laws hold universally true, in all me-chanical powers or engines; therefore it is easy (fromthese simple principles) to compute the power of anyengine, either simple or compound; for it is only to findhow much swifter the power moves than the weight, orhow much farther it moves in the same time; and somuch is the power (and time of producing it) increased,by the help of the engine.

Article 17.

GENERAL RULES FOR COMPUTING THE POWER OF ANT ENGINE.

1. Divide either the distance of the power from itscentre of motion, by the distance of the weight from itscentre of motion. Or,

2. Divide the space passed through by the power,by the space passed through by the weight, (this spacemay be counted either on the arch, or on the perpen-dicular described by each,) and the quotient will showhow much the power is increased by the help of the en-gine; then multiply the power applied to the engine, bythat quotient, and the product will be the power of theengine, whether simple or compound.

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