修道院公学（14）

“The boy's, then?”

“Possibly, if we could prove a bicycle to have been in his possession. But this we have utterly failed to do. This track, as you perceive, was made by a rider who was going from the direction of the school.”

“Or towards it?”

“No, no, my dear Watson. The more deeply sunk impression is, of course, the hind wheel, upon which the weight rests. You perceive several places where it has passed across and obliterated the more shallow mark of the front one. It was undoubtedly heading away from the school. It may or may not be connected with our inquiry, but we will follow it backwards before we go any farther.”

We did so, and at the end of a few hundred yards lost the tracks as we emerged from the boggy portion of the moor. Following the path backwards, we picked out another spot, where a spring trickled across it. Here, once again, was the mark of the bicycle, though nearly obliterated by the hoofs of cows. After that there was no sign, but the path ran right on into Ragged Shaw, the wood which backed on to the school. From this wood the cycle must have emerged. Holmes sat down on a boulder and rested his chin in his hands. I had smoked two cigarettes before he moved.

“Well, well,” said he, at last. “It is, of course, possible that a cunning man might change the tyre of his bicycle in order to leave unfamiliar tracks. A criminal who was capable of such a thought is a man whom I should be proud to do business with. We will leave this question undecided and hark back to our morass again, for we have left a good deal unexplored.”

We continued our systematic survey of the edge of the sodden portion of the moor, and soon our perseverance was gloriously rewarded. Right across the lower part of the bog lay a miry path. Holmes gave a cry of delight as he approached it. An impression like a fine bundle of telegraph wires ran down the centre of it. It was the Palmer tyre.

“那么，这是那个孩子的？”

“有可能，只要我们能够证明这个孩子有车。可是我们根本不能证明。你看，自行车的轨迹说明汽车人是从学校方向骑来的。”

“也许是向学校去的？”

“不，不，亲一爱一的华生。当然是承担重量的后轮，压出的轨迹深。这里有几处后轮的轨迹和前轮的一交一叉，前轮的轨迹较浅被埋住了。无疑是从学校来的。这和我们的侦查也可能有关，也可能无关，不过在我们离开之前，还是返回去看一下吧。”

我们返回去，走了几百码，来到一块沼泽地，自行车的轨迹就不见了。我们沿着小道继续走，到了一处有泉水滴答作响的地方。这里又有自行车的轨迹，可是几乎被牛蹄的痕迹抹掉。再往前就没有痕迹了，那一条小道一直通向"萧岗"，也就是学校后面的那片小树林。车子一定是从小树林里出来的。福尔摩斯坐在一块大石头上，用手托住下巴。我一抽一了两支烟，他都一动未动。

过了一会儿他说：“有可能是这样，一个狡猾的人，会把自行车的外胎换了，留下的轨迹使人不易辨认。我是愿意跟能够想出这种办法的罪犯打一交一道的。这个问题我们先不管，还是注意那片湿地，那里不少地方我们还没有查看。”

在那片湿地的边缘上，我们继续系统地进行查看，不久就收到了良好的成绩。在这片湿地的低洼处，有条泥泞的小道，福尔摩斯走近小道的时候，高兴得喊出了声。在小道的正中象是一捆电线摩一擦地面留下了痕迹。这正是帕默轮胎的痕迹。