《瓦尔登湖·第十六章·冬天的湖·The Pond in Winter》第10节
While I was surveying, the ice, which was sixteen inches thick, undulated under a slight wind like water. It is well known that a level cannot be used on ice. At one rod from the shore its greatest fluctuation, when observed by means of a level on land directed toward a graduated staff on the ice, was three quarters of an inch, though the ice appeared firmly attached to the shore. It was probably greater in the middle. Who knows but if our instruments were delicate enough we might detect an undulation in the crust of the earth? When two legs of my level were on the shore and the third on the ice, and the sights were directed over the latter, a rise or fall of the ice of an almost infinitesimal amount made a difference of several feet on a tree across the pond. When I began to cut holes for sounding, there were three or four inches of water on the ice under a deep snow which had sunk it thus far; but the water began immediately to run into these holes, and continued to run for two days in deep streams, which wore away the ice on every side, and contributed essentially, if not mainly, to dry the surface of the pond; for, as the water ran in, it raised and floated the ice. This was somewhat like cutting a hole in the bottom of a ship to let the water out. When such holes freeze, and a rain succeeds, and finally a new freezing forms a fresh smooth ice over all, it is beautifully mottled internally by dark figures, shaped somewhat like a spider’s web, what you may call ice rosettes, produced by the channels worn by the water flowing from all sides to a centre. Sometimes, also, when the ice was covered with shallow puddles, I saw a double shadow of myself, one standing on the head of the other, one on the ice, the other on the trees or hill-side.
注释摘要
梭罗在这一段里把测量学变成了一种近乎玄思的练习。他在冻住的瓦尔登湖面上走着，手里拿着罗盘、测链和测深绳，脚底是十六英寸厚的冰，但就在这样的厚度上，一阵微风吹过，冰面竟然像水面一样起伏波动。他说测量师都知道，冰上没法用水平仪，因为你找不到一个稳固的参照面。他做了个实验：把水平仪的两条腿支在岸上，第三条腿立在冰上，瞄准湖对岸一棵树上的刻度杆，结果冰面极微小的起…