Can a boat ride a big wheel upward?
船也能坐大轮子往上走？
船在水上走，我们并不觉得奇怪。
A boat moving on water does not seem strange.
可是，船还能坐着大轮子往上走吗？
But can a boat ride a big wheel upward?
在英国苏格兰，有一座叫福尔柯克轮的升船设备。
In Scotland, in the United Kingdom, there is a boat lift called the Falkirk Wheel.
这里有两条运河，一条高，一条低。
There are two canals here, one higher and one lower.
船要从低处去高处，就可以借助这个轮子。
A boat can use this wheel to move from the lower level to the higher one.
轮子并不是把船从水里直接拉起来。
The wheel does not pull the boat directly out of the water.
船先进入一个装着水的长水槽，仍然浮在水里。
The boat first enters a long trough filled with water and continues to float in it.
可以把水槽想成一个装水的大盒子，船就在盒子里面。
You can imagine the trough as a large box of water, with the boat inside.
轮子的两边各有一个这样的水槽。
There is one such trough on each side of the wheel.
轮子转动时，一个水槽往上走，另一个往下走。
As the wheel turns, one trough moves up and the other moves down.
看到这里，你可能会问：水槽会跟着翻过去吗？
At this point, you may ask: does the trough turn upside down with it?
不会，水槽在移动时仍然保持水平。
No: the trough stays level as it moves.
水平就是两边一样高，不是一边高、一边低。
Level means that both sides are at the same height, rather than one side being higher than the other.
关键藏在支臂末端的圆圈里。
The key lies inside the ring at the end of the arm.
支臂像轮子伸出的手臂，它带着水槽往上或往下移动。
An arm is like an outstretched arm of the wheel: it carries the trough upward or downward.
水槽装在圆圈里面，但没有和圆圈固定成一块。
The trough sits inside the ring, but it is not rigidly fixed to the ring as one piece.
所以，圆圈转的时候，水槽也能在圈里面转。
So when the ring turns, the trough can also turn inside it.
外面的圆圈向一边转，里面的水槽就朝反方向转。
The outer ring turns in one direction, while the trough inside turns in the opposite direction.
这样，水槽的开口就能一直朝上，而不是跟着圆圈翻过去。
This lets the trough's opening keep facing upward instead of turning upside down with the ring.
让它们按这样的方式转动，靠的是一套齿轮。
A set of gears makes them rotate in this coordinated way.
齿轮是边上有小齿的轮子，彼此咬合的小齿能带动轮子转。
Gears are wheels with small teeth around their edges; teeth that mesh can make the wheels turn.
对船来说，变化的是它所在的高度，不是它要翻个身。
For the boat, what changes is its height; it does not have to turn upside down.
下次看见轮子转，别只看轮子，也看看它带着的东西怎么动。
The next time you see a wheel turn, look at how the object it carries moves too.
看起来是一起移动的两个部分，方向却可以不一样。
Two parts that appear to move together can still have different orientations.
