瓦尔登湖:The Pond in Winter3
A factory-owner， hearing what depth I had found， thought that it could not be true， for， judging from his acquaintance with dams，sand would not lie at so steep an angle. But the deepest ponds are not so deep in proportion to their area as most suppose， and， if drained， would not leave very remarkable valleys. They are not like cups between the hills； for this one， which is so unusually deep for its area， appears in a vertical section through its centre not deeper than a shallow plate. Most ponds， emptied， would leave a meadow no more hollow than we frequently see. William Gilpin， who is so admirable in all that relates to landscapes， and usually so correct， standing at the head of Loch Fyne， in Scotland， which he describes as "a bay of salt water， sixty or seventy fathoms deep，four miles in breadth，" and about fifty miles long， surrounded by mountains， observes， "If we could have seen it immediately after the diluvian crash， or whatever convulsion of nature occasioned it，before the waters gushed in， what a horrid chasm must it have appeared！
"So high as heaved the tumid hills， so low Down sunk a hollow bottom broad and deep，Capacious bed of waters."
But if， using the shortest diameter of Loch Fyne， we apply these proportions to Walden， which， as we have seen， appears already in a vertical section only like a shallow plate， it will appear four times as shallow. So much for the increased horrors of the chasm of Loch Fyne when emptied. No doubt many a smiling valley with its stretching cornfields occupies exactly such a "horrid chasm，" from which the waters have receded， though it requires the insight and the far sight of the geologist to convince the unsuspecting inhabitants of this fact. Often an inquisitive eye may detect the shores of a primitive lake in the low horizon hills， and no subsequent elevation of the plain have been necessary to conceal their history. But it is easiest， as they who work on the highways know， to find the hollows by the puddles after a shower. The amount of it is， the imagination give it the least license， dives deeper and soars higher than Nature goes. So， probably， the depth of the ocean will be found to be very inconsiderable compared with its breadth.
As I sounded through the ice I could determine the shape of the bottom with greater accuracy than is possible in surveying harbors which do not freeze over， and I was surprised at its general regularity. In the deepest part there are several acres more level than almost any field which is exposed to the sun， wind， and plow. In one instance， on a line arbitrarily chosen， the depth did not vary more than one foot in thirty rods； and generally， near the middle， I could calculate the variation for each one hundred feet in any direction beforehand within three or four inches. Some are accustomed to speak of deep and dangerous holes even in quiet sandy ponds like this， but the effect of water under these circumstances is to level all inequalities. The regularity of the bottom and its conformity to the shores and the range of the neighboring hills were so perfect that a distant promontory betrayed itself in the soundings quite across the pond， and its direction could be determined by observing the opposite shore. Cape becomes bar， and plain shoal， and valley and gorge deep water and channel.
When I had mapped the pond by the scale of ten rods to an inch，and put down the soundings， more than a hundred in all， I observed this remarkable coincidence. Having noticed that the number indicating the greatest depth was apparently in the centre of the map， I laid a rule on the map lengthwise， and then breadthwise， and found， to my surprise， that the line of greatest length intersected the line of greatest breadth exactly at the point of greatest depth，notwithstanding that the middle is so nearly level， the outline of the pond far from regular， and the extreme length and breadth were got by measuring into the coves； and I said to myself， Who knows but this hint would conduct to the deepest part of the ocean as well as of a pond or puddle？ Is not this the rule also for the height of mountains， regarded as the opposite of valleys？ We know that a hill is not highest at its narrowest part.
Of five coves， three， or all which had been sounded， were observed to have a bar quite across their mouths and deeper water within， so that the bay tended to be an expansion of water within the land not only horizontally but vertically， and to form a basin or independent pond， the direction of the two capes showing the course of the bar. Every harbor on the sea-coast， also， has its bar at its entrance. In proportion as the mouth of the cove was wider compared with its length， the water over the bar was deeper compared with that in the basin. Given， then， the length and breadth of the cove， and the character of the surrounding shore， and you have almost elements enough to make out a formula for all cases.
In order to see how nearly I could guess， with this experience，at the deepest point in a pond， by observing the outlines of a surface and the character of its shores alone， I made a plan of White Pond， which contains about forty-one acres， and， like this，has no island in it， nor any visible inlet or outlet； and as the line of greatest breadth fell very near the line of least breadth，where two opposite capes approached each other and two opposite bays receded， I ventured to mark a point a short distance from the latter line， but still on the line of greatest length， as the deepest. The deepest part was found to be within one hundred feet of this， still farther in the direction to which I had inclined， and was only one foot deeper， namely， sixty feet. Of course， a stream running through， or an island in the pond， would make the problem much more complicated.
一个工厂主，听说了我所发现的深度之后，认为这不是真实的，因为根据他熟悉水闸的情况而言，细沙不能够躺在这样峻削的角度上。可是最深的湖，按它的面积的比例来看，也就不像大多数人想象的那么深了，如果抽干了它的水来看一看，留下的并不是一个十分深透的山谷。它们不是像山谷似的杯形，因为这一个湖，就它的面积来说已经深得出奇了，通过中心的纵切面却只是像一只浅盘子那样深。大部分湖沼抽干了水，剩下来的是一片草地，并不比我们时常看到的低洼。威廉。吉尔平在描写风景时真是出色，而且总是很准确的，站在苏格兰的费因湖湾的尖端上，他描写道，“这一湾盐水，六七十英寻深，四英里阔，”约五十英里长，四面全是高山，他还加以评论：“如果我们能在洪水泛滥，或者无论大自然的什么痉挛造成它的时候，在那水流奔湍人内以前，这一定是何等可怕的缺口啊！”“高耸的山峰升得这高，低洼的湖底沉得这低，阔而广，好河床――。”可是，如果我们把费因湖湾的最短一条直径的比例应用在瓦尔登上，后者我们已经知道，纵切面只不过是一只浅盘形，那末，它比瓦尔登还浅了四倍。要是费因湖湾的水一古脑儿倒出来，那缺口的夸大了的可怕程度就是这样。无疑问的，许多伸展着玉米田的笑眯眯的山谷，都是急流退去以后露出的“可怕的缺口”，虽然必须有地质学家的洞察力与远见才能使那些始料所未及的居民们相信这个事实。在低低的地平线上的小山中，有鉴识力的眼睛可以看出一个原始的湖沼来，平原没有必要在以后升高，来掩盖它的历史。但是像在公路上做过工的人一样，都很容易知道，大雨以后，看看泥水潭就可以知道哪里是洼地。这意思就是说，想象力，要允许它稍稍放纵一下，就要比自然界潜下得更低，升起得更高。所以，海洋的深度，要是和它的面积一比，也许是浅得不足道也。
我已经在冰上测量了湖的深度，现在我可以决定湖底的形态了，这比起测量没有冻冰的港湾来要准确得多，结果我发现它总的说来是规则的，感到吃惊。在最深的部分，有数英亩地是平坦的，几乎不下于任何阳光下、和风中那些被耕植了的田野。有一处，我任意地挑了一条线，测量了三十杆，可是深浅的变化不过一英尺；一般他说来，在靠近湖心的地方，向任何方向移动，每一百英尺的变化，我预先就可以知道，不过是三四英寸上下的深浅。有人惯于说，甚至在这样平静的、沙底的湖中有着深而危险的窟窿，可是若有这种情况，湖水早把湖底的不平一律夷为平底了。湖底的规则性，它和湖岸以及邻近山脉的一致性，都是这样地完美，远处的一个湖湾，从湖的对面都可以测量出来，观察一下它的对岸，已可以知道它的方向。岬角成了沙洲和浅滩，溪谷和山峡成了深水与湖峡。
当我以十杆比一英寸的比例画了湖的图样，在一百多处记下了它们的深度，我更发现了这惊人的一致性了。发现那记录着最大深度的地方恰恰在湖心，我用一根直尺放在最长的距离上画了一道线，又放在最宽阔的地方画了一道线，真使人暗暗吃惊，最深处正巧在两线的交点，虽然湖的中心相当平坦，湖的轮廓却不很规则，而长阔的悬殊是从凹处量出来的，我对我自己说道，谁知道是否这暗示了海洋最深处的情形之正如一个湖和一个泥水潭的情形一样呢？这一个规律是否也适用于高山，把高山与山谷看作是相对的？我们知道一个山的最狭的地方并不一定是它的最高处。
五个凹处中有三个，我全去测量过，口上有一个沙洲，里面却是深水，可是那沙洲的目的，不仅是为了面积上扩张，也为了向深处扩张，形成一个独立的湖沼似的盆地，而两个岬角正表明了沙洲的方位。海岸上的每一个港埠的入口处也都有一个沙洲。正如凹处的口上，阔度大于它的长度，沙洲上的水，在同比例度内，比盆地的水更深。所以把凹处的长阔数和周遭的湖岸的情形告诉给你之后，你就几乎有充分的材料，可以列出公式，凡是这一类情况都用得上它。
我用这些经验来测量湖的最深处，就凭着观察它的平面轮廓和它的湖岸的特性，为了看看我测量的准确程度如何，我画出了一张自湖的平面图，白湖幅员占四十一英亩左右，同这个湖一样，其中没有岛，也没有出入口：因为最阔的一道线和最狭的一道线相当接近，就在那儿，两个隔岸相望的岬角在彼此接近，而两个相对的沙洲彼此远距，我就在最狭的线上挑了一个点，却依然交叉在最长的一条线上的，作为那里是最深处。最深处果然离这一个点不到一百英尺，在我定的那个方向再过去一些的地方，比我预测的深一英尺，也就是说，六十英尺深。自然，要是有泉水流入，或者湖中有一个岛屿的话，问题就比较复杂了。
英语 文学 散文本文地址：http://www.dioenglish.com/writing/essay/48355.html
