MACHINES FOR LUMBER, TOO

Machines dug and loaded and delivered the coal that keeps your house

warm. Machines helped cut the lumber that went into building your house,

too.

Far out in the woods, power-driven saws sliced quickly through the

trunks of great trees. Caterpillar tractors hauled the logs out along

rough forest trails.

Perhaps the cats, using booms, lifted the logs onto extra-long trailers

behind trucks and started them on the way to the sawmill. Or the cats

may have snaked the logs to a river so they could float downstream to a

sawmill.

[Illustration]

No matter how the logs reached the sawmill, they were put at last onto

belts which pushed them against huge whirling saws. A whole set of saws,

all whining and screaming at once, turned the thick log into boards.

Other machines planed the boards to make them smooth and then cut them

to exactly the right sizes. Finally lift-trucks picked up great piles of

board at once, whizzed them away and hoisted them elevator-fashion into

high stacks.

[Illustration]

[Illustration]

Machines at Work · 第 22 / 37 题