Medieval siege 中世纪攻城战-5

With the manuscript as a starting point, Wayne used a combination of engineering theory and trial and error to come up with a working model.
"All right, you'll look out...you get the camera, you'll see from the..."
The prototype looks promising¹ to Marcus Brandt, a carpenter who will help Wayne build the trebuchet. But there is a problem, the model rocks dangerously. This would be a serious flaw in a full-size trebuchet with several tons in motion.
"The machine basically tends to wanna tip forward as that weight comes down, it wants to drop straight down, so it tends to pull the machine forward, making it in this case tilt²."
To resolve the problem, Wayne reexamines the medieval illustrations of this type of trebuchet. He's struck by the fact that many have wheels, so he decides to build a new model. Not only do wheels eliminate the tendency for it to tip over, the movement also boosts the trebuchet's performance.
"Shoot it away, Come on..."
Hew³ doubts that wheels will make a trebuchet throw farther, so he insists on a demonstration⁴. For the first throw, Hew holds down the model, the projectile⁵ travels 20 feet.
"Now let's try with letting it loose."
"Letting it loose."
"Yeah, well, certainly better, isn't it? Yes!"
"Yes, I just didn't do enough long..."
When the trebuchet is allowed to roll, the missile goes an extra ten feet, why?
The falling counterweight drives the trebuchet forward like a pitcher⁶ stepping forward. This adds momentum⁷ to the throw. The forward motion also permits the counterweight to drop further in a straighter line. The closer the counterweight follows this optimal⁸ path, the more energy it captures for throwing.
"What I find odd is the idea about it moving and having to move, in order to give more energy to the missile. I would have thought it was, on the face of it, nonsense. But we've seen Wayne has tried it, it goes further, and it can't be argued with."
Now that Wayne has confidence in his model, the project moves to Lock Ness in the Scottish Highlands for the full-scale test. The trials will take place in the shadow of castle Urquhart which may have been besieged⁹ with similar weapons during Edward I's Scottish campaigns seven hundred years ago. Wayne and Hew arrive at castle Urquhart, to inspect the timber that is delivered by barge¹⁰. As in the Middle Ages, heavy-duty English oak is the choice for building the carriage and trestles

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projectile: n. 射弹（如子弹、炮弹等）
pitcher: n. 投手
momentum: n. 动力，动量
barge: n. 驳船
trestle: n. 脚手架

1 promising   

adj.有希望的，有前途的

参考例句：

• The results of the experiments are very promising.实验的结果充满了希望。
• We're trying to bring along one or two promising young swimmers.我们正设法培养出一两名有前途的年轻游泳选手。

2 tilt   

v.(使)倾侧；(使)倾斜；n.倾侧；倾斜

参考例句：

• She wore her hat at a tilt over her left eye.她歪戴着帽子遮住左眼。
• The table is at a slight tilt.这张桌子没放平，有点儿歪.

3 hew   

v.砍；伐；削

参考例句：

• Hew a path through the underbrush.在灌木丛中砍出一条小路。
• Plant a sapling as tall as yourself and hew it off when it is two times high of you.种一棵与自己身高一样的树苗，长到比自己高两倍时砍掉它。

4 demonstration   

n.表明，示范，论证，示威

参考例句：

• His new book is a demonstration of his patriotism.他写的新书是他的爱国精神的证明。
• He gave a demonstration of the new technique then and there.他当场表演了这种新的操作方法。

5 projectile   

n.投射物，发射体；adj.向前开进的；推进的；抛掷的

参考例句：

• The vertical and horizontal motions of a projectile can be treated independently.抛射体的竖直方向和水平方向的运动能够分开来处理。
• Have you altered the plans of the projectile as the telegram suggests?你已经按照电报的要求修改炮弹图样了吗?

6 pitcher   

n.(有嘴和柄的)大水罐；(棒球)投手

参考例句：

• He poured the milk out of the pitcher.他从大罐中倒出牛奶。
• Any pitcher is liable to crack during a tight game.任何投手在紧张的比赛中都可能会失常。

7 momentum   

n.动力，冲力，势头；动量

参考例句：

• We exploit the energy and momentum conservation laws in this way.我们就是这样利用能量和动量守恒定律的。
• The law of momentum conservation could supplant Newton's third law.动量守恒定律可以取代牛顿第三定律。

8 optimal   

adj.最适宜的；最理想的；最令人满意的

参考例句：

• What is the optimal mix of private and public property rights in natural resources?私人和国家的自然资源产权的最适宜的组合是什么？
• Optimal path planning is a key link for the sailing contest.帆船最优行驶路径规划是帆船比赛取胜的关键环节。

9 besieged   

包围，围困，围攻( besiege的过去式和过去分词 )

参考例句：

• Paris was besieged for four months and forced to surrender. 巴黎被围困了四个月后被迫投降。
• The community besieged the newspaper with letters about its recent editorial. 公众纷纷来信对报社新近发表的社论提出诘问，弄得报社应接不暇。

10 barge   

n.平底载货船，驳船

参考例句：

• The barge was loaded up with coal.那艘驳船装上了煤。
• Carrying goods by train costs nearly three times more than carrying them by barge.通过铁路运货的成本比驳船运货成本高出近3倍。