There would soon be an explosion; the kettle would be burst open. It is in this way that boiler explosions are often caused. When there is too much steam in a boiler, and it cannot get out, it presses against the sides of the boiler, until at last the boiler bursts.

很快，就会发生爆炸，将水壶炸开。锅炉经常发生爆炸，就是这个原因。锅炉里蒸汽太多，又出不来的时候，蒸汽就会紧紧压在锅炉壁上，直到最后把锅炉炸开。

To prevent these accidents, every boiler has a safety-valve, or an opening through which the steam can escape when its pressure begins to get too great. It is only when something goes wrong with the safety-valve thatan explosion occurs.

为了避免这种事故，所有的锅炉都装着安全阀，这是一个开口，当蒸汽的压力太大的时候，就能通过这个开口逃出去。只有在安全阀出问题的时候，才会发生爆炸。

Steam requires seventeen hundred times more room than the water from which it is formed. One kettle full of water would make enough steam to fill seventeen hundred kettles.

一份水变成的蒸汽，需要1700份这么多水的空间才能盛下。一把盛满水的水壶，里面的水变成的蒸汽，可以盛满1700个水壶呢!

It is heat that makes steam take up so much more room than water. The heat drives the tiny pieces of which water is made further and further away from each other.

是什么让蒸汽占的地方，比水多了这么多呢?是热量。热量让水分子之间的距离越来越远。

This power of steam is a very good thing when it is properly used. It is this pressure that does the work in all steam-engines, and that sets their parts in motion.

如果用得合适，蒸汽的力量是一件非常好的事情。所有的蒸汽机，利用的都是这种力量。它们要靠蒸汽的力量，来推动部件运动。

The first really good steam-engines were made by James Watt, about a hundred years ago. It was by noticing the steam making the lid of a kettle dance and rattle, that he first began to think of the great power of steam.

最早一批实用的蒸汽机，是詹姆斯·瓦特在大约100年前制造的。瓦特当初看到了蒸汽推动水壶的盖子跳舞，发出响声，才开始思考蒸汽的强大力量。
 

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