Then, when it hardens, the part that is between the laths holds the rest of the plaster up and against the wall."

David nodded, but they were in the back hall now, with the back stairs going up out of it, and he forgot the carpenters and the laths.

Under the back stairs were some stairs that went down to the cellar, and the foreman started down.

"Be careful of the steps, Davie," said the foreman. "They have to have these rough boards on them now, while the workmen are here, so that the real steps won't get all dirty and worn. When the men are almost through, about the last thing they do is to lay floors and put nice boards on the stairs."

David couldn't see very well, but he could feel that the boards of the stairs were uneven and rough, and some of them were small; but he was careful, and he went slowly, and at last he was on the cellar floor.

Far off in the very end of the cellar he saw a lantern lighted, and a flickering light which moved about, high up.

Then, as he got used to the darkness, he saw the legs of two men; and they had great wrenches and were doing something to long pipes, and they had a candle which they held close up to the pipes, so that they could see.

And the pipes went along close to the beams overhead, so that the men were all the time b.u.mping their heads and knocking their elbows on the beams, and they didn't have room enough to work.

That was the reason why David had seen only their legs when he first came down.

It wasn't a very convenient way to work, but the men didn't seem to mind. Perhaps they were used to it.

"Are those the pipes that the water goes through?" David asked.

"Yes, Davie," the foreman said. "It comes in through the wall there, close down to the floor, from that pipe that you saw the men laying in the street.

"Then it goes up and through these pipes to the back of the cellar, and then up again to the kitchen and the pantry and the bathrooms.

"It isn't much fun being down here, is it?"

"No," David said, "it isn't."

The foreman laughed.

"Well, you wait a half a jiffy and we'll go up."

So David waited while the foreman took a paper out of his pocket.

And first he looked at the paper and then he looked at the pipes, and then he looked at the paper again.

Then he folded the paper and put it into his pocket, and he took David's hand and they went up the cellar stairs, and through a door into the kitchen.

There David saw the legs of two other men who were lying down under the sink.

They had a stump of a candle, too, for David could see its flickering light.

And there was a kind of a lamp out on the floor beyond, and it burned with a sputtering and a hissing and a roaring, and it threw a big bluish kind of a flame straight out, like water out of a hose.

David watched the men for nearly a minute without saying anything, but he couldn't guess what they were up to.

"What are they doing?" he asked at last.

"They're putting in the waste pipe and the trap," said the foreman; "but you don't know what that is, of course. They're putting in the pipe that the water runs through when it runs out of the sink."

"Oh, I know," David cried. "It's for the dirty water that the pots and pans have been washed in; the soapy water."

"That's just right, Davie."

"Well," David said, "why do they have to be lying down to do it? I should think they'd rather do it standing up or sitting down."

At that, one of the men poked his head out and smiled at David.

"You got that just right, too," he said; "but here's where it has to go, and there's no other way that I know of."

"The pipe has to be under the sink, Davie, for the water to run into it," the foreman said. "Now come on, and we'll go upstairs again."

So the foreman and David went up the back stairs very slowly and carefully, for there were rough boards on those stairs, too; and they went through a door and through the upstairs hall, and through another door into a small square room.

The foreman said that that room would be the bathroom. No plaster was on the walls yet, but the laths were all on. And there wasn't any bathtub yet, nor any basin; only some pipes sticking up out of the floor.

And David saw the bodies and the legs of two more men.

These men had their heads and shoulders through a great square hole in the floor, and their bodies and their legs were lying on the floor and sticking out straight.

David laughed. "Water-pipe men are funny men," he said.

One of the men lifted his head out of the hole in the floor and smiled at David, but he didn't say anything.

"They're putting in the waste pipe and the trap," the foreman said; "that is, the pipe that the water will run through when it runs out of the bathtub. A tub will be here Davie, after the floor is laid."

David nodded.

"Would you like to be a plumber, Davie?" the foreman asked, smiling.

David shook his head.

"I think I'd better go now," he said. "My kitty won't know where I am."

So the foreman laughed, and he tucked David under his arm and carried him downstairs and out of the front door, and he set him down on the ground.

"Good-bye, Davie," said the foreman.

"Good-bye," said David.

And he took hold of the handle of his cart, and walked home as fast as he could, dragging his cart, and his shovel and his hoe rattled in the bottom of it.

When he got home, there was his cat waiting for him.

David dropped the handle of his cart, and ran around to the back of the house and got an old grocery box that he used to play with.

He kept all his things at the back of the house: old broken grocery boxes and old tin cans and rows of bottles, some of them filled with water and some filled with thin mud and some empty, and nails and pieces of iron and sticks; but not his toys.