instructed to crawl back into the fissure so as to be out of danger in case anything gave way.  At one time a stick which had been carelessly tied did fall, and it might have badly hurt some one had we not observed this precaution.  When we had raised the material to the second ledge we transferred operations to the top ledge, and when the materials had been hauled up to this point we finally rigged up our fall and tackle in the old oak tree itself.

The Tree House.

[Illustration:  Fig. 138.  Main Girder of the Tree House.]

[Illustration:  Fig. 139.  Top View of the Platform.]

[Illustration:  Fig. 140.  The Frame of the House.]

The tree had two large limbs which extended out at a wide angle from the main trunk.  Across these two limbs, at about seven feet out, we laid our first girder, nailing it securely in place.  Then to the main trunk we nailed the second girder on a level with the first.  Diagonal braces were extended from the trunk to support the ends of this girder, and a tie piece was nailed to the braces, as shown in Fig. 138, to prevent them from spreading.  The girders were rough sticks about 4 inches in diameter and 10 feet long.  We cut flat faces on them at the points where they were nailed to the tree, and then, to make them doubly secured, we nailed cleats, or blocks of wood, to the tree under them.  The floor beams were then laid across and nailed to the girders.  They were cut to a length of 10 feet so as to project beyond the outer girder to provide for a piazza overhanging the Goblins’ Platform.  Six floor beams were used, spaced 20 inches apart.  All branches projecting up between the beams were then cut away and a flooring of slabs was laid on.  To the main trunk six feet above the flooring, a stick or (to use the technical term), “wall plate,” was nailed on, and its ends were supported by upright posts resting on the platform.  Thirty inches from the outer end of the platform two more posts were erected eight feet high and secured by sticks nailed across from the other posts, and also by a second wall plate connecting their upper ends.  Four more posts were erected, one between each pair of the corner posts, and then we were ready to enclose the framing.

The sidewalls were first clapboarded, because we were afraid the roof would not hold us until the framing had been strengthened by nailing on the siding.  Slab boards were used for this purpose.  Beginning at the bottom, the boards were laid on, each lapping over the one below, as shown in Fig. 141, so as to shed water.  In each side we cut a window opening and nailed on a window casing of the type shown in Fig. 142, which will be described in a moment.  As soon as the clapboards were applied, we nailed on the rafters and then applied the roofing.  The same principle was here used for shedding water.  The lowest board was first laid on, and then the others were successively applied, each lapping over the one below.