Slowly, slowly up the mountain crept the long train. It was carrying the Overall Boys far away from lovely Lake Lucerne. It was taking them over the wonderful BrÜnig Pass. It was carrying them even more slowly down, down the steep slope on the other side toward the head of the deep valley, where lay the pretty Swiss village of Meiringen.

As the boys stood by the car window they could see the long line of track far below them. Sometimes when their train passed a sharp curve, they could even see the engine at one end of the train and the last car at the other end.

They glided over high bridges above torrents of water which dashed down the mountain to join the blue lake in the valley below.

It was wonderful—the mountains, the torrents, the lakes, and the strong train which carried them over everything! It was all so wonderful, the boys had no words to express their delight. For the first time on their long journey they were almost silent.

Once in a while one of the boys would cry: "Look at that great waterfall!" or "See the precipice right below us!" or "Watch us cross that high bridge!"

It was much more exciting than the ride in the thunder storm up Mount Rigi, but at last even this ride came to an end.

Yes, the wonderful ride over the BrÜnig Pass ended at Meiringen, but the more wonderful tramp over the Great Scheidegg Pass was to begin at Meiringen, and the boys were to have other strange experiences down in the deep, green valley. The most exciting of them all came the very next morning.

There was an early breakfast eaten in the pretty garden of the hotel, then their father said:

"Now for the fun! Yesterday we went over a mountain. To-day we shall go through one."

"Are we going through a tunnel?" cried Joe.

"No, indeed!" said their father. "At least it is not a tunnel made by men. Come and see what you think of it."

They were soon tramping along the village street toward the high mountain at the head of the narrow valley. A swift river hurried past them to join the lake at the other end of the valley. It was the river Aar.

The boys saw where the river had overflowed its banks in the springtime, when the snows melted and the heavy rains came. They were told that the bridges were often washed away, and that sometimes great masses of rocks came tearing down the mountain side, right into the little village, crushing and burying everything in their path.

The party quickly left the village far behind them, and each step brought them nearer to the high mountain wall close ahead.

"How shall we get over that mountain, father?" asked Joe. "Shall we have to climb to the top?"

"No, Joe," said his father. "We shall do no climbing to-day. I believe we can go through it, if this swift river can."

"Of course we can!" shouted Jack. "Let's follow the river."

So they followed a footpath along the banks of the noisy river. Soon the banks began to grow high and steep. At last they rose straight up on both sides, until the boys could see only a narrow strip of blue sky far above them.

"The mountain has cracked open!" shouted Joe. "We are in the crack!"

"So we are!" cried Jack. "I believe the river did it. See it come tearing along!"

"Look ahead of us!" said Joe. "There isn't room even for a path. A board walk has been fastened with iron rods to the wall. It hangs right over the rushing water. What if it should break while we are on it! I am not sure that I want to go any farther."

"Come, now, don't be a coward, Joe," said his father. "The Swiss government builds these paths, and they are built strong. We are safe."

So on they tramped through the great crack in the mountain. In some places the path hung high over the swift waters. In other places it was tunneled through the dark rocks. But always it followed the deep, narrow crack, with the noisy river at its bottom and a bit of blue sky far, far above.

For nearly a mile the boys followed this path. In many places the river was so noisy they had to shout to make each other hear. But at last they came out on the other side of the mountain.

They had not climbed the mountain, and they had not gone around it. They had gone through it. And more wonderful still, the great river Aar has been carrying its waters through the mountain for ages and ages.

Close beside the river, at the end of the path, was a tiny shop kept by a little old woman and her granddaughter.

The little girl served the boys to raspberry lemonade, and she sold them picture post cards showing the strange path over which they had just come.

Then back they went into the mountain crack—over the footpath hanging high above the rushing water, and through the small, dark tunnels, until once more they were in the lovely green valley of Meiringen.