在日本这块台风横扫地震频发的土地上，有500多座国内最高但看起来最脆弱的老建筑——本质宝塔——居然矗立了数个世纪，这是为什么呢?有记录显示，在过去的1400年间，只有两座倒塌了。其他消失的塔都毁于由闪电或内战而引起的大火。1995年灾难性的阪神地震致使6400人丧生，毁坏了高架公路，夷平了办公大楼并且将神户港口区域摧毁殆尽。尽管大地震将京都附近的东寺(Toji temple)周围的大量建筑夷为平地，可寺里宏伟的五层宝塔却完好无损。

In a land swept by typhoons and shaken by earthquakes, how have Japan's tallest and seemingly flimsiest old buildings - 500 or so wooden pagodas - remained standing for centuries? Records show that only two have collapsed during the past 1400 years. Those that have disappeared were destroyed by fire as a result of lightning or civil war. The disastrous Hanshin earthquake in 1995 killed 6,400 people, toppled elevated highways, flattened office blocks and devastated the port area of Kobe. Yet it left the magnificent five-storey pagoda at the Toji temple in nearby Kyoto unscathed, though it levelled a number of buildings in the neighbourhood.

多年来日本学者一直迷惑为什么这些细长的建筑物能如此稳固。仅仅在30年前，建筑界的从业者们才有足够信心建造高于十二层的钢筋混凝土办公大楼。位于东京市巾心、高达36层的霞关(Kasumigaseki)大厦是日本第一座摩天大楼，由于运用了特殊的减震装置来减弱地震中突如其来的侧向运动，在1968年建成之时被认为是现代工程学上的里程碑。

然而早在公元826年，建筑大师Kobodaishi仅仅使用木栓和楔子就能使他的术质建筑屹立不倒了。大师毫不犹豫地将他的东寺大宝塔矗立起来，宝塔拔地而起55米，高耸入云，这高度可相当于11个世纪之后才建成的霞关摩天大楼的一半啊。显而易见，当时的日本木匠懂得一些窍门让建筑物可以顺风摇摆，不与自然力量对抗，而是顺应自然，从而稳稳矗立。但究竟是什么样的窍门呢?

Japanese scholars have been mystified for ages about why these tall, slender buildings are so stable. It was only thirty years ago that the building industry felt confident enough to erect office blocks of steel and reinforced concrete that had more than a dozen floors. With its special shock absorbers to dampen the effect of sudden sideways movements from an earthquake, the thirty-six-storey Kasumigaseki building in central Tokyo - Japan's first skyscraper - was considered a masterpiece of modern engineering when it was built in 1968.

6世纪时，多层宝塔从中国传入日本。像在中国一样，这些宝塔最初是随着佛教而被引进的，往往建在重要的寺庙内。中国人用砖石来造宝塔，内设楼梯，后来这些宝塔就主要用作守望塔。然而当这些宝塔传入日本时，其建筑风格被大刀阔斧地加以改动以适应当地的情况。宝塔高度降低，通常是五层而不是中国的九层，大多为木质结构。日本宝塔没有什么实用性，更多是当作艺术品，所以没有接梯。由于每年夏天日本都会遭到台风的蹂躏，日本的建筑者们学会了将建筑物的屋檐远远延伸到墙外面去。这样雨水就不会倾泻到墙上。中韩两国的宝塔就没有日本宝塔这样的悬空屋檐。

日本寺庙建筑的屋檐悬垂于建筑物的侧面之外部分的宽度达到建筑物总宽的一半或更多。出于同样的原因，日本宝塔的建造者们通过采用较重的陶瓦来覆盖这些延伸的屋檐从而大量增加自身的重量，而不像许多中国宝塔那样采用瓷瓦。

Yet in 826, with only pegs and wedges to keep his wooden structure upright, the master builder Kobodaishi had no hesitation in sending his majestic Toji pagoda soaring fifty-five metres into the sky - nearly half as high as the Kasumigaseki skyscraper built some eleven centuries later. Clearly, Japanese carpenters of the day knew a few tricks about allowing a building to sway and settle itself rather than fight nature's forces. But what sort of tricks?

但这并不能完全解释日本宝塔所具有的巨大弹性。答案难道是这样的吗?筑像高大的松树那样，日本宝塔拥有巨大的柱子，比如被称为shinbashira的中柱，在台风或是地震中这个中流砥柱可以弯曲和摇摆?几个世纪以来，很多人都这样认为。但答案没有这么简单，因为让人惊讶的是中柱并没有承担任何重量。事实上，在某些日本宝塔中，中柱甚至并未接触到地面，而是从塔的顶部悬吊下来，从建筑物的巾部松松地垂下。整个建筑的重量完全依托在12根外柱和4根内柱上。

那中柱究竟有什么作用呢?理解它的作用的最好办法耽是去观看由京都工艺纤维大学的建筑工程师 Shuzo Ishida所制作的视频。由于热衷研究日本宝塔，Ishida先生被学生戏称为“宝塔教授”。他制作了一系列的宝塔模型并且在实验室中的振动台上进行试验。简而言之，中柱就像一个巨大的静止钟摆。在明显没有先进数学运算辅助的情况下，古代的工匠似乎就已经掌握了1000多年后用于建设日本第一座摩天大接的原理。通过不断摸索，反复试验，古代工匠们终于发现了其中的奥妙：在压力下，宝塔松散堆叠的楼层可以被造得能够独立蜿蜒前行或后退。从侧面看，宝塔就像在跳蛇舞，因为连在一起的每个楼层都以与上下层相反的方向移动。中柱从建筑物中央的孔贯穿而下，使得单个接层不会移得太远，因为每移动一段距离之后，楼层就会擅上中柱，能量也就通过柱子转走了。

The multi-storey pagoda came to Japan from China in the sixth century. As in China, they were first introduced with Buddhism and were attached to important temples. The Chinese built their pagodas in brick or stone, with inner staircases, and used them in later centuries mainly as watchtowers. When the pagoda reached Japan, however, its architecture was freely adapted to local conditions - they were built less high, typically five rather than nine storeys, made mainly of wood and the staircase was dispensed with because the Japanese pagoda did not have any practical use but became more of an art object. Because of the typhoons that batter Japan in the summer, Japanese builders learned to extend the eaves of buildings further beyond the walls. This prevents rainwater gushing down the walls. Pagodas in China and Korea have nothing like the overhang that is found on pagodas in Japan.

日本宝塔另外一个奇怪特征就是没有一根承重立柱能和上层相应的立柱连在一起，这是因为日本宝塔每一层的接层面都比下一层的要小，宝塔于是从下往上逐渐变细。换句话说，一座5层高的日本宝塔里甚至没有一根柱子从下往上贯穿宝塔，来承担建筑物的重量。更令人惊讶的是日本宝塔的每一个单独楼层间实际上都不相连，这一点不同于其他任何地方的同类建筑。它们就像一棵帽子一样只是被一层一层地叠加起来。有意思的是，现在的日本建筑规定可不允许这种建筑形式的存在。

那么关于超宽的房檐又做何解释呢?就把它们看成走钢丝演员手里的平衡杆吧。平衡杆两端的重量越大，走钢丝演员在行走过程中就越容易掌越握衡。日本宝塔与此同理。ishida先生说：“日本宝塔所有侧面的屋檐都向外延展，就好像平衡杆一样，这样建筑物就算在地震最强烈的震动中也能优雅地摆动，而从不突然晃动。日本千年前的建筑大师们再次预先使用了现代结构工程学的理念。

The roof of a Japanese temple building can be made to overhang the sides of the structure by fifty per cent or more of the building's overall width. For the same reason, the builders of Japanese pagodas seem to have further increased their weight by choosing to cover these extended eaves not with the porcelain tiles of many Chinese pagodas but with much heavier earthenware tiles.

But this does not totally explain the great resilience of Japanese pagodas. Is the answer that, like a tall pine tree, the Japanese pagoda - with its massive trunk-like central pillar known as shinbashira - simply flexes and sways during a typhoon or earthquake? For centuries, many thought so. But the answer is not so simple because the startling thing is that the shinbashira actually carries no load at all. In fact, in some pagoda designs, it does not even rest on the ground, but is suspended from the top of the pagoda - hanging loosely down through the middle of the building. The weight of the building is supported entirely by twelve outer and four inner columns.

And what is the role of the shinbashira, the central pillar? The best way to understand the shinbashira's role is to watch a video made by Shuzo Ishida, a structural engineer at Kyoto Institute of Technology. Mr Ishida, known to his students as 'Professor Pagoda' because of his passion to understand the pagoda, has built a series of models and tested them on a 'shake- table' in his laboratory. In short, the shinbashira was acting like an enormous stationary pendulum. The ancient craftsmen, apparently without the assistance of very advanced mathematics, seemed to grasp the principles that were, more than a thousand years later, applied in the construction of Japan's first skyscraper. What those early craftsmen had found by trial and error was that under pressure a pagoda's loose stack of floors could be made to slither to and fro independent of one another. Viewed from the side, the pagoda seemed to be doing a snake dance - with each consecutive floor moving in the opposite direction to its neighbours above and below. The shinbashira, running up through a hole in the centre of the building, constrained individual storeys from moving too far because, after moving a certain distance, they banged into it, transmitting energy away along the column.

Another strange feature of the Japanese pagoda is that, because the building tapers, with each successive floor plan being smaller than the one below, none of the vertical pillars that carry the weight of the building is connected to its corresponding pillar above. In other words, a five- storey pagoda contains not even one pillar that travels right up through the building to carry the structural loads from the top to the bottom. More surprising is the fact that the individual storeys of a Japanese pagoda, unlike their counterparts elsewhere, are not actually connected to each other. They are simply stacked one on top of another like a pile of hats. Interestingly, such a design would not be permitted under current Japanese building regulations.

And the extra-wide eaves? Think of them as a tightrope walker's balancing pole. The bigger the mass at each end of the pole, the easier it is for the tightrope walker to maintain his or her balance. The same holds true for a pagoda. 'With the eaves extending out on all sides like balancing poles,' says Mr Ishida, 'the building responds to even the most powerful jolt of an earthquake with a graceful swaying, never an abrupt shaking.' Here again, Japanese master builders of a thousand years ago anticipated concepts of modern structural engineering.