go over the side of the world when the sun set and keep up with it on the other side of the world,  太阳下山的时候走完世界的一面，并且一直跟着太阳走过世界的另一面，

he would be back again where he started the next morning.  那么他就会在第二天早晨回到他出发的地方。

He would then have gone round the world in one day.  那他就是在一天之内环游了全世界。

But to do that he would have to travel over 1,000 miles an hour to keep up with the sun for each of the twenty-four hours in a day and night. 但是要跟得上太阳的脚步,他必须得昼夜24小时时刻保持每小时1000英里以上的速度才行。

All around the outside of the world—as you probably know 也许你知道，世界的外围包裹着一层空气，

is an ocean of air that covers everything on the world as the ocean of water covers everything in the sea.  这个空气就像海洋一样覆盖着世界上所有的东西，就像大海里的水覆盖着海里的所有东西一样。

What you probably don't know is that this ocean of air is wrapped only round the World—it does not fill the sky. 但你可能不知道这个空气的海洋仅仅是包裹着我们的世界，天空中并没有。

Men and animals live in this ocean of air as fish live in the ocean of water,  人和动物居住在这个空气的海洋中，就像鱼住在海里一样。

and if a huge giant picked you out of the air you would die just as quickly as a fish does when taken out of the sea.  如果一个大巨人把你抱出了这个空气海洋，你很快就会死掉，就像鱼从水里捞出来就会死一样。

The air is thick near the ground but gets thin and thinner the higher up you go off the ground.  靠近地面的地方空气比较浓厚，但是离开地面越高空气就越来越稀薄。

That's why airplanes can go up but a few miles high—there is not enough air to hold up the plane,  这就是为什么飞机只能飞到几英里高的地方—更高的地方没有足够的空气来支撑飞机，

for the plane must have air to rest on and for its propeller to push against  因为飞机必须依靠空 气，让它的推进器推动空气使它飞行，

just as a boat in the water must have water to rest on and water for its propeller to push against.  就像船必须停在水面上，它的推进器才可以推开水使它前行。

Or if if s a jet plane, it must have air to feed its jet motors.  如果是喷气式飞机的话，必须得有空气来填充它的喷气式发动机。

An airplane could not rise beyond the ocean of air and sail off into the sky  飞机不能脱离空气的海洋飞到没有空气的高空中，

where there is no air any more than a steamship on the sea could rise out of the water and sail off up into the air. 就像海上的轮船不能离开水 行驶到空中一样。

There is only one thing that men can send up high enough to travel above the ocean of air.  人只能把一样东西发射到没有空气的高空中运行，那就是火箭，

That is a rocket which doesn't depend on air for its motor or to hold it up.  它不需要空气推动它的发动机，也不需要空气撑托它。