“Oh!” gasped Sue.

“Oh, my!” cried Bunny, and then, before Sue could stop him, her brother ran to the edge of the hill.  He saw his toy engine and cars rolling over and over toward the lake at the bottom of the hill, and, without stopping a second, over the hill went Bunny Brown himself—­slipping, sliding and falling down!

“Oh, Bunny!  Come back!  Come back!” cried Sue, very much excited.

But Bunny was rolling over and over down the hill after his train, and he could not answer.

CHAPTER VI

AFTER THE LOST COW

Bunny Brown was thinking of two things when he started to roll downhill.  One was that his train might roll into the water and be spoiled, for his father had told him that there were bits of electrical machinery on the engine that would be spoiled if water touched them.

Then Bunny thought of himself rolling into the water, for the hill was steep on this shore of the lake, and any one rolling down, if he were not stopped before he reached the bottom, would be almost sure to go into the lake.

“But I don’t mind so much about myself,” thought Bunny.  “My clothes will get wet, but I’ve got on an old suit and water won’t hurt that.  It won’t hurt me, either, for I get wet when I go in swimming, and I can swim now if I have to.  But my train can’t swim, ’cause that’s iron, and iron will sink, daddy told me.  So I’ve got to catch the train before it goes into the lake.”

The thought of this made Bunny try to roll over and over faster, so he could win in the race down the hill between himself and the train.  If he could get hold of the train before it touched the water all would be well, he hoped.  He could toss the train to one side, out of harm’s way, even if he fell into the water himself.

“But can I get it?” thought Bunny, as he rolled over and over.

He could hear Sue calling to him at the top of the hill, on the very edge of which he had made the curve of his track.  He realized now that it was too near the edge.  What Sue was saying Bunny could not hear, but he imagined she was begging him to stop rolling downhill and come back to her.

“As if I could!” thought Bunny to himself.  “This rolling downhill isn’t any fun.  I didn’t really mean to do it, but I couldn’t help it.  I wanted to run or slide down.  There are too many stones for rolling.”

Indeed there were, for the slope of the hill down to the lake was not of soft grass.  Instead it was of gravel and stone and these were very rough for a small boy to roll on.  Still Bunny did not mind if he could get his locomotive and train of cars.

He could see them just ahead of him, rolling over and over just as he was doing.  Of course there was no electricity in the toy locomotive now.  The current, as the electricity is called, was all in the rails, going into them from the batteries, and from there it went into the motor or the wheels, gears and other things inside the engine that made it roll along.