Whatever you call it, if you want to send a stone

不管你叫它什麼，如果你想送一塊石頭

bouncing across the surface of the water

撲騰

there's a surprising amount of science and technique involved.

這裡面涉及到了驚人的科學和技術。

It's almost the same science that allowed engineer and inventor

這幾乎是同樣的科學，讓工程師和發明家。

Barnes Wallis to create the bouncing bomb

巴恩斯-沃利斯創造的反彈炸彈。

used in World War Two, to attack German dams -

攻擊德軍水壩 --

the so-called Dambusters raid.

所謂的Dambusters突襲。

OK, so first you need to find the right stone.

好了，首先你要找到合適的石頭。

Wonky shaped, thick-set, pockmarked stones are not recommended.

不建議使用形狀怪異、鑲嵌厚實、有痘印的石頭。

Don't worry about it being perfectly smooth,

不要擔心它是完美的平滑。

but the ideal stone is flat and round -

但理想的石頭是平的和圓的 -

rather like a digestive biscuit, though maybe not quite as big.

頗像消化餅乾，雖然可能沒有那麼大。

It just depends on the size of your hand.

只是要看你手的大小。

The key to a good throw is spin.

好的投擲，關鍵在於旋轉。

The gyroscopic effect

陀螺效應

stabilizes the stone, as long as it is spinning fast enough,

穩定石頭，只要石頭轉得夠快。

preventing it from tipping over and falling into the water -

防止其傾覆和落水----------------------------。

just like a spinning top has to be spinning fast enough to stay upright.

就像一個旋轉的頂部必須要轉得足夠快才能保持直立。

Amazingly, it's this same gyroscopic effect

令人驚奇的是，正是這種陀螺效應

that keeps the Earth spinning on its fixed axis in space.

使地球在太空中以固定的軸線自轉。

There are lots of ways to grip and throw the stone,

握石、拋石的方法很多。

but here's a good one to try.

但這裡有一個很好的嘗試。

Grip the stone with your thumb and fingers,

用拇指和手指握住石頭。

with your index finger around the edge.

用食指繞著邊緣。

As you throw, bend down as low as you can and aim towards the water,

投擲時，儘量彎下腰，瞄準水面。

keeping the stone horizontal.

保持石頭的水準。

A good angle for the stone to bounce when it hits the water

石頭落水後的反彈角度很好。

is about 20 degrees.

是20度左右。

At this angle, even a beginner can get away with a sloppy throw.

在這個角度，即使是初學者，也可以擺脫馬虎的投擲。

But if you're good, and you can throw the stone both level and fast,

但如果你的技術好，而且你能把石頭扔得既平又快。

then go for as shallow an angle as you can.

然後儘可能的去找一個淺的角度，你可以。

It's your index finger that will do all the work

是你的食指在做所有的工作。

generating speed and spin in the direction of the two arrows.

在兩個箭頭的方向上產生速度和旋轉。

The whip of your wrist creates extra spin.

手腕的鞭打會產生額外的旋轉。

Lift your thumb off the stone at the last minute.

在最後一刻將拇指從石頭上抬起來。

Get it right, and you'll see more than two bounces.

搞好了，你就會看到不止兩個彈子。

Who knows, on flat water

誰知道呢，在平坦的水面上

you might get the stone to bounce 10, 15 or even 20 times.

你可能會讓石頭反彈10次、15次甚至20次。

But don't expect to get into the Guinness Book of Records.

但不要指望能進入吉尼斯紀錄。

In 2013, Kurt "Mountain Man" Steiner from the US

2013年，來自美國的 "山地人 "庫爾特?

managed to get his stone to bounce a record-breaking 88 times!

成功地讓他的石頭彈跳了88次，創下了記錄!