011 摩天大楼

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Four thousand five hundred years ago, the Egyptians built the pyramids of Giza as grand and impressive tombs for their pharaohs

四千五百年前，埃及人为他们的法老建造了吉萨金字塔，作为宏伟而令人印象深刻的陵墓。

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The largest of these enormous monuments is almost 147 meters high, and for four thousand years, it was the tallest man-made structure on earth

这些巨大建筑中最大的一座有近147米高，并且在四千年间，它一直是地球上最高的人造建筑。

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Today the tallest man-made structures are skyscrapers

如今，最高的人造建筑是摩天大楼。

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Every day in cities around the world, millions of people go to work in towers made of steel and glass

每天，在世界各地的城市里，数百万人前往由钢铁和玻璃建造的高楼中工作。

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These modern structures exhibit the best in construction technology and engineering skills

这些现代建筑展示了最先进的建筑技术和工程技艺。

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And the modern city could not function without them

而现代城市离不开它们。

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When the demand for living and working space in the limited area of a city's downtown grows, there is nowhere to build but up

当城市中心有限区域内对居住和工作空间的需求增长时，除了向上建造，别无选择。

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Smaller buildings are demolished, and taller buildings are built to replace them

较小的建筑被拆除，更高的建筑取而代之。

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The streets of Manhattan in New York City, where real estate for new buildings is limited, are lined with tall, gleaming office towers

在纽约市的曼哈顿，可用于新建建筑的土地有限，街道两旁排列着高耸、闪亮的办公大楼。

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During the first half of the nineteenth century, buildings were rarely taller than five stories

在19世纪上半叶，建筑很少超过五层高。

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Buildings higher than this would have been impractical — office workers would have become exhausted from climbing so many stairs!

比这更高的建筑当时是不切实际的——上班族爬那么多楼梯会疲惫不堪！

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Then in 1853, Elisha Otis invented the safety elevator

随后在1853年，伊莱沙·奥蒂斯发明了安全电梯。

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Previous elevators were used mostly for freight, not people

此前的电梯主要用于运货，而非载人。

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If the cable that held the elevator snapped, the elevator would fall, killing those inside

如果拉住电梯的缆绳断掉，电梯就会坠落，导致里面的人丧生。

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The safety elevator has mechanical locks that automatically hold the elevator firmly in place if the cable snaps

安全电梯装有机械锁，一旦缆绳断裂，会自动将电梯牢牢固定在原位。

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The invention of the safety elevator made tall buildings a practical reality

安全电梯的发明让高层建筑成为了实用的现实。

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While Elisha Otis was improving the elevator, other inventors were hard at work improving water pumps

在伊莱沙·奥蒂斯改进电梯的同时，其他发明家也在努力工作，改进水泵。

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As cities expanded, more powerful pumps were needed to provide water to their distant areas

随着城市扩张，需要更强大的水泵向偏远地区供水。

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Eventually pumps became powerful enough to supply water to great heights, enabling cities to grow upward as well as outward

最终，水泵变得足够强大，能向很高的高度供水，这使得城市既能向外发展，也能向上发展。

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In the middle of the nineteenth century, manufacturers developed the process for mass-producing steel, which is stronger and lighter than iron

在十九世纪中叶，制造商开发出了大规模生产钢材的工艺，这种材料比铁更坚固、更轻。

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With steel beams, buildings could be built around a metal frame, rather than out of stone walls

有了钢梁，建筑就可以围绕金属框架来建造，而不必依靠石墙。

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Stone walls are impractical for very tall buildings

石墙对于非常高的建筑来说并不实用。

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If stone blocks are piled too high one on top of another, their combined weight will crush the bottom blocks

如果石块一个叠一个堆得太高，它们加起来的重量会压碎底部的石块。

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Steel-frame construction and improvements like the safety elevator and powerful water pumps allowed buildings to soar higher than ever before

钢框架建筑结构，加上安全电梯和强力水泵等改进，让建筑能够比以往任何时候都建得更高。

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Soon builders were competing to construct taller and taller skyscrapers

很快，建造者们开始竞相建造越来越高的摩天大楼。

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When Walter Chrysler, founder of an automobile company, started work on the Chrysler Building in New York

当一家汽车公司的创始人沃尔特·克莱斯勒开始在纽约建造克莱斯勒大厦时，

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he wanted it to be the tallest building in the world

他想让它成为世界上最高的建筑。

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But during its construction, work began on an even taller building — the Bank of Manhattan Building

但在施工期间，一座更高的建筑——曼哈顿银行大厦——也破土动工了。

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Chrysler, however, had kept something secret: inside his building a giant spire was under construction

然而，克莱斯勒一直保守着一个秘密：在他大厦的内部，一个巨大的尖顶正在秘密建造。

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After the Bank of Manhattan Building was finished in 1930, the spire was placed on top of the Chrysler Building

1930年，曼哈顿银行大厦完工后，这个尖顶被安装到了克莱斯勒大厦的顶部。

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It extended the building's height to about 319 meters, making it the world's tallest building

它将建筑高度提升到约319米，使其成为当时世界最高的建筑。

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But the competition for the tallest skyscraper did not end there

但争夺最高摩天大楼的竞争并未就此结束。

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A year later the Empire State Building was finished, standing almost 450 meters high

一年后，帝国大厦竣工，高度接近450米。

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When it became possible to build skyscrapers hundreds of meters tall, unusual engineering challenges surfaced

当建造数百米高的摩天大楼成为可能时，一些不寻常的工程难题出现了。

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Strong winds can cause a tall building to sway back and forth

强风会导致高楼来回摇摆。

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To stop the building from shaking, many skyscrapers have a central core of steel around the main elevator shaft

为了阻止建筑晃动，许多摩天大楼在主电梯井周围设有一个中央钢芯。

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This makes the skyscraper more rigid

这能让摩天大楼更加坚固。

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Also skyscrapers must use a special type of glass

此外，摩天大楼必须使用一种特殊的玻璃。

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Tempered glass, or safety glass, is stronger than ordinary glass

钢化玻璃，或称安全玻璃，比普通玻璃更坚固。

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When safety glass breaks, it shatters into small pieces with rounded edges

当安全玻璃破碎时，它会裂成许多边缘圆钝的小碎片。

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Ordinary glass in a skyscraper window would be hazardous; if it broke, large, sharp pieces would fall and injure people on the sidewalks below

摩天大楼窗户使用普通玻璃会很危险；一旦破碎，大块的锋利碎片会掉落，伤及下方人行道上的行人。

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Tremendous skill is required to build skyscrapers

建造摩天大楼需要高超的技术。

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The steel beams must be riveted and welded together before the floors and walls can be put in place

必须先铆接和焊接好钢梁，才能安装楼板和墙体。

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Before workers were required to wear safety harnesses, it was very dangerous work

在要求工人必须佩戴安全绳之前，这是一项非常危险的工作。

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One mistake or an unexpected gust of wind could send a construction worker falling to his death

一个失误或者一阵突如其来的强风，都可能导致建筑工人坠落身亡。

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For much of the twentieth century, the Mohawk Indians were considered some of the best construction workers

在二十世纪的大部分时间里，莫霍克印第安人被认为是最优秀的建筑工人之一。

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Many of them fearlessly strode along the narrow beams of steel, hundreds of meters off the ground, earning the nickname skywalkers

他们中的许多人无畏地行走在离地数百米的狭窄钢梁上，因而赢得了“空中行者”的绰号。

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New skyscrapers are still being built

新的摩天大楼仍在不断建造中。

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As of 2014, the tallest skyscraper on earth is the Burj Khalifa in Dubai

截至2014年，地球上最高的摩天大楼是迪拜的哈利法塔。

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It is 828 meters tall and was completed in 2009

它高达828米，于2009年竣工。

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In 2014 plans to construct an even taller skyscraper in Saudi Arabia — the Kingdom Tower — were announced

2014年，沙特阿拉伯宣布了建造一座更高摩天大楼——王国塔——的计划。

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If completed, the Kingdom Tower will have three hundred floors and reach one kilometer into the sky!

如果建成，王国塔将拥有三百层楼，高达一千米，直入云霄！

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Thanks to advances in materials and technology, today's skyscrapers stand many times higher than the pyramids

得益于材料和技术的进步，今天的摩天大楼比金字塔高出许多倍。

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And architects and engineers keep dreaming about even taller structures

建筑师和工程师们仍在梦想着建造更高的建筑。

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Future man-made structures will likely reshape the urban landscape — just as the first skyscrapers did over a hundred years ago

未来的人造建筑很可能会重塑城市景观——正如一百多年前最早的摩天大楼那样。