When they arrived near the pond, Oliver pointed to a little mound, not far from the edge of the water, which overlooked the principal skating-ground of the village boys in winter.

“There, Rollo,” said Oliver, “there’s the place for a fort.  Many a pleasant time we have had there, in a clear winter night, watching the skaters all the way up to the head of the pond.  The fires look splendidly.”

“It is a good place for a lookout,” said Rollo; “but then I wouldn’t build it here.  Let us go down nearer the pond.”

“No,” said Oliver; “if we go down near the pond, as likely as not, the first skating night, some of the boys will tear our fort all to pieces.”

“What if they do?” said Rollo.

“I want it to last all winter,” said Oliver.

Rollo yielded to Oliver’s wishes, and they began together to unbind their load of boards and tools.

“Come, Nathan,” said Oliver, “we want you to help us now.”

Rollo and Nathan measured with the reel and line, while Oliver planted a stake firmly in the snow at the four corners of the square.

According to Jonas’s advice, the evening before, they had agreed to make their fortification twelve feet square, and the walls about one foot thick.

Rollo and Nathan held the cord, stretched from corner to corner, just along the surface of the snow, while Oliver, with the shovel, cut the snow square down to the ground, more than a foot and a half deep.

In this way they went round the whole enclosure, outside.  They then went inside, and, by a similar process, cut away the snow so as to leave an unbroken line of snow wall about ten feet square and one foot wide.

“There,” said Oliver, “there are the sills, as Jonas called them.  It is what I call a good foundation.”

After this, Oliver asked Rollo to bring in the measuring-board inside of the fort.

Oliver and Rollo remembered what Jonas had told them about “commanding and obeying,” and agreed to take turns in being “director.”

It was Oliver’s turn for the first hour, and Rollo was to obey him.  Nathan was to assist them both, when he was wanted.

Oliver, therefore, took the command, and directed where and how to cut out the snow, in the manner which Jonas had described.

They proceeded with the measuring-board, to mark off, and cut out by it, solid blocks of snow about four feet long, one foot wide, and one thick.

Rollo laid down the measuring-board on the snow, and then both of them, with the shovels, cut down the snow perpendicularly along the edges, so as to have all the snow-blocks of precisely the same length, breadth, and thickness.  These they laid in courses, on the top of the foundation.

It took just three blocks to form a side, excepting the side where the door was, which they left three feet wide.

After working more than two hours, and laying two courses, they shoveled out all the broken snow that remained inside, and then sat down on the sled to eat their luncheon and rest.