These trees he fells toward each other, so that, if possible, their tops meet. When this is done, he has the backbone for his dam. Then he fills in with stakes and small logs and finally plasters up all the holes with mud and sod. When he has finished, it is as tight as any man-made dam.
他让这些树彼此靠近，这样，如果可能的话，树的顶部就会相接。当这一切完成后，他就有了建造水坝的支柱。然后他用树桩和小圆木填充，最后用泥和草皮把所有的洞都填满。当完工时，就像任何人造水坝一样坚固。
But if trees are not available, he can do without them; he can cut logs, roll them into place, and make a dam wholly out of logs. The beaver seems to understand how powerful moving water is. At any rate, his dam usually curves upstream in the middle, and every engineer knows that a dam built in this way is the strongest. The beaver also provides a waste waterway which runs around one end of the dam. So, when the water is high, it flows around the end instead of washing away the top of the dam. He is very watchful of the dam, and if it begins to leak, he investigates at once.
但如果没有树，他也可以照样建造；他可以砍伐原木，把它们滚到合适的地方，然后完全用原木筑坝。海狸似乎明白流动的水的力量。无论如何，他的水坝通常在中间向上游弯曲，每个工程师都知道以这种方式建造的水坝是最坚固的。海狸还做出了一条环绕水坝一端的废弃水道。所以当水位很高的时候，水会绕着水坝的末端流动，而不是冲走水坝的顶部。海狸非常小心，如果水坝开始漏水，就立即进行调查。
