It would take a whole book just to list the other machines that help different kinds of farmers. But here are some that are fun to know about:

One clever contraption attached to a tractor grabs hold of nut trees and gives them a hard shaking. The nuts fall on the ground, ready for a kind of giant vacuum sweeper to come and suck them into a truck.

Crops that grow underneath the earth need their own sort of harvesting machine. There are potato diggers and many others. The sugar beet digger works in a particularly clever way. Machine fingers feel for the beet tops. They set off a knife which cuts the tops off while other fingers lift the beet out and put it on an elevator which removes the clods of dirt as it travels. Once in a while the machine makes a mistake and delivers a stone, or a chunk of mud at the end of the elevator. Men do nothing but throw the junk away and let the beets slide into the truck that travels alongside.

A farmer always has to keep an eye on what his implements are doing, unless he has a helper who rides along on machines like this big reaper. When the tractor

pulls a cultivator or a planter, the driver must turn his head often to see how the work is going. For a long time, farmers complained that this was a pain in the neck, and they really meant that their necks hurt from turning so much. Some of them actually went back to using horses, because they could either walk or sit behind horse-drawn machines. So the farm machine makers had to change as many of the machines as they could, placing them beside the tractor or out in front where the driver can watch what is going on.

Tractors themselves come in many sizes and shapes. Some are built very high off the ground so they can pass over tall crops without hurting the plants. Some have four wheels that can be pushed close together for work in one field and pulled wide apart for work in another. Some have three wheels.

Mostly, farmers buy tractors the way people buy automobiles. They pick a model they happen to like and then argue that it’s the best in the world. Of course, a little light “cub” tractor is easier to handle than a big one, but it can’t do the hard work of a heavy model with huge rear wheels and tires. And here’s something about the tires—farmers often fill them with water instead of air to give them more weight when they grip the ground. In winter, these farmers must put antifreeze not only in the radiator but in the tires as well!

On enormous farms where very heavy work must be done, there are often crawler tractors to do it. Instead of tires they have caterpillar treads that give a better grip on the ground. Then they can pull a whole string of plows the way you see them in the picture, staggered out behind.

This kind of tractor was first named caterpillar by only one manufacturer. But people liked the idea, and they began to call all crawlers caterpillars.

A caterpillar is powerful enough to push a snow plow, too. Or it can bulldoze out a hole for a watering pond or a cellar for a new building.