When the first post was in place, the students gave three cheers. The Sylph whistled lustily, and just at that moment the two Chesterfield barges darted into Beech Hill Lake. They went over to the grove, where they picked up a dozen of the Topovers. It did not look as though the principal of the institute had much influence over them; for taking the Topovers into their boats indicated that they were bent upon mischief.

Captain Gildrock said nothing about the barges and their occupants, and did not seem to notice them. The work proceeded as though they had been on the other side of the lake. The Sylph moved the caisson into position for laying the second post, which was on the side, to avoid changing the mooring-ropes as much as possible.

The Chesterfields rowed up to a point where they could see what was going on, and watched the work for a while. It was no "circus" for them, and they soon pulled to the shore on the west side of Hornet Bay. Dory watched them from the pilot-house, and soon had occasion to report to the principal that the Chesterfields and Topovers had hold of the mooring-rope of the caisson. He had not finished what he was saying before the stone boat suddenly moved towards the site of the building, and then knocked Bolly's square out of place.

Captain Gildrock took command this time himself. The chief quarryman was a constable. He asked all the rest of the men and boys to act as his posse, and all hands were ordered into the steamer. The mischief-makers had taken the mooring-rope into the Dasher, and had headed out into the lake. The steamer darted after them. The boats let go the rope, and attempted to escape by the way they had come. The Sylph was too much for them, and both boats were captured. The principal directed the constable to take the two coxswains and Tom Topover out of them, and they were shut up in the ice-house on board of the steamer.

The others were permitted to depart, which they were glad to do when they found that Captain Gildrock "meant business." The prisoners were kept till noon in the ice-house, when they were taken before a magistrate, and a complaint made for trespass and for stealing the boats on a former occasion. They were sent to the lock-up, but Colonel Buckmill came over before night and bailed out Commodore Twinker and Jeff Monroe.

At the trial a case was made out, and all the defendants were subjected to a fine, which Tom's father would not pay, and he was kept in jail for two weeks. Colonel Buckmill paid those of his students. He had warned them before of the peril of meddling with the Beech Hill students, and probably he did it again on this occasion. What good it did we may learn from another book of this series. At any rate the Chesterfields and the Topovers did not go to Beech Hill Lake again that year.

Bolly arranged the square again, and the rest of the posts were set. The sills were then loaded on the caisson, from which they were laid on the posts. The rest of the lower timbers were put in place by the students, with the help of the laborers only. The rafts of boards, which had been secured to the shore until they were wanted, were towed to the frame, and the racket of six-and-twenty hammers resounded through the grove for the next two afternoons. The boys learned to drive nails, but there was not so much fun in it, they found, when they came to make a business of it. The sawing and fitting of the boards for the floor gave some variety, and they were required to sharpen their judgment in the prevention of waste.

While the students were at their studies, the laborers carried the timbers of the frame to the platform, and the next job was to put them together in sections. The caisson was securely moored off the east end of the site by ropes leading to the shore. The boom of the derrick was "topped up" until it was perpendicular to the deck of the craft. Slings were rigged at the intersection of the three end posts with the plates, from which three lines came together at the foot of the middle post.

"Now, boys, we want three sailors," said Captain Gildrock, who attended personally to the rigging. "What they have to do may be considered dangerous in the country, though not more so than going upon the cross-trees of a ship, and I shall call for volunteers."

Every student raised his hand, for all of them wanted the difficult positions. The principal selected three who had had some experience in going aloft; and they were Dory Dornwood, Matt Randolph and Luke Bennington.