The Busy Shore: The Block and Tackle System

The author explains how a block and tackle system multiplies human strength and illustrates a number of uses for them.

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Like all moving machines, friction takes its due, and each sheave demands a part of the effort. Sailors figure that 5-8% is added for each sheave, and a formula estimating a somewhat greater loss is used by fishermen (Pull on the active tine = P; W = Weight lifted; F = number of falls, or lines, from the moving block.)
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