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.

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.