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How to Build a Cave - DIY Cave - excerpt from the book "The Scientific American Boy"

How to Build a Cave - DIY Cave - excerpt from the book "The Scientific American Boy" by A. Russell Bond
Bill had read somewhere that if you dig a cave under a tree the roots of the tree will support the ground on top and make a natural and substantial roof. It sounded very reasonable, we thought; in fact, we never questioned the truth of the statement, because we had somehow gotten the notion that books were never wrong, and that whatever was set up in type must surely be so. But events proved that the man who wrote that book had never attempted to build a cave in the manner he described, at least not in the loose,  sandy soil of south Jersey. A large spreading cedar was selected as the tree which should support the roof of our cave. It was situated on a mound at the edge of the woods. First a passageway, or ditch, was dug at the bottom, and then we begun tunneling in the side of the mound under the roots of the tree. For a while the ground above held, and our tunnel had reached a length of about four feet, when suddenly, without the slightest warning, the sandy soil gave way and we were engulfed. Bill, who was furthest within the cave, was almost entirely covered, while I was buried to the shoulders. A crowd of boys came to our assistance and dug us out. Poor Bill was almost smothered before they scooped the sand away from around his mouth and nose. The boys made slow work of it, having to dig with their hands and a couple of shingles, because the two spades we had were buried with us at the bottom of the cave.

Of course, this little episode gave us a scare, but it was only temporary. We swore every one to secrecy, so that Mr. Clark, the principal, wouldn’t hear of the mishap and suppress any further cave building. It was obvious that the only roof we could depend on for our cave would be a wooden roof. If we had been at Willow Clump Island we would have gotten any amount of slabs from the lumber mills across the river.

One of our schoolmates, a day scholar, came to the rescue. His name was Chester Hill, a little bit of a chap, about the shortest for his age that I have ever seen. His name was so at variance to his size that we called him “Hillock,” for short. Now Hillock lived on a farm about eight miles from school, and used to drive in every day on a farm wagon. He had helped us dig the cave under the cedar tree, and when he learned that we would need some lumber to build a safe cave, he told us that he had an uncle who owned a lumber mill on the Morris River, from whom he was sure we could get all the slabs we wanted. Of course, we were delighted, and laid our plans for an elaborate cave house. Hillock promised to be on hand on the following Saturday afternoon with his load of lumber.

Excavating for the Cave.

We immediately set out to make the necessary excavation. The side of a bushy knoll was chosen as a suitable site. First we carefully transplanted the bushes that grew in the square we had marked out for the cave, and cutting the sod into squares, piled it all neatly to one side. Then we shoveled away the top-soil and heaped it up for future use. After that we dug away the sandy subsoil. The cave proper we planned to make about 8 feet by 10 feet, with a passageway 2 feet wide and 6 feet long, leading in from a large bush at the base of the knoll. Our excavation was therefore somewhat T-shaped (see Fig. 182). At the deepest part we had to dig down about 10 feet.

Fig. 182. Excavation for the Cave.

The digging was all done by Saturday, when Hillock pulled up with a big load of slabs. Slabs are a very unsatisfactory kind of wood for most purposes. Being the outside cut, they are usually very irregular and weak in spots. In many places they are almost clear bark. Of course, had our pocketbooks permitted, we would have used stout scantlings for the corner posts of our cave house and substantial boards for the walls, roof and flooring, but we had to be content with materials at hand. Eight of the best slabs were selected for our corner posts; four of them we cut to the length of 8 feet and the others to a length of 6 feet. The long slabs were set up at the rear of the cave, two at each corner, one flat against the rear wall, with its edge buried in the corner, and the other against the side wall, with its edge tight against the rear slab, as in Fig. 183. The same was done at the forward corners with the shorter slabs. A couple of slabs were now set up on each side of the passageway, and a corresponding pair against the rear wall. The upper and lower ends of the uprights were then connected with slabs, called string pieces.

Fig. 183. Framework of the Cave.

The sides were now boarded up with upright slabs nailed to the string pieces. An opening 3 feet 6 inches high was left in the forward wall for a passageway. Several slabs were now placed on the edge across the bottom of the cave, to  serve as floor beams, upon which a flooring of slabs was laid. Next the rafters were set in place, one on each upright slab. Slots were cut in the ends of the uprights to receive the rafters, which were slabs placed on edge. As the forward uprights were 2 feet shorter than the rear ones, the rafters were given a good slant, so that the roof would properly shed any water that might soak in through the ground above.

Fig. 184. The Siding and Flooring.

The roof was laid on the same way that we had made the roof of our tree house; that is, a slab was first nailed at the forward end of the rafters with its edge projecting far enough to make a good eave; then the second slab was nailed on, with its edge overlapping the first, and a third with its edge overlapping the second, and so on with the rest. At the rear end of the roof a hole was cut, into which we fitted a piece of stovepipe. We didn’t plan to have a fire in the house, but set the stovepipe in place to provide the necessary ventilation. As the pipe had an elbow in it, there was no danger of rain or dirt falling through it. The upper end of the stovepipe was concealed among some rocks at the top of the knoll.
A suitable flooring was now laid in the passageway, and the sides were boarded up to a height of 2 feet from the floor at the entrance to a height of 3 feet 6 inches at the inner end. A roof of slabs was nailed on, and then we were ready to cover our slab house with dirt.

Fig. 185. Notching in the Rafters.

Covering the Cave.

We avoided piling on the dirt very deep, because there was danger of breaking in the roof with a heavy load. A thin layer of sand covered with the top-soil brought up the level to about that of the rest of the knoll. Then the sod was laid back in place and well watered, and the few bushes planted back in their original positions. Our sodding should have been done in the spring for best results. The frost soon killed the grass, and the bushes withered away. But a few cents’ worth of grass seed was sowed in, and in time gave the knoll a very natural appearance. A bush at the bottom concealed the entrance of the cave, so that no one who was not in the secret would have suspected that beneath that innocent looking knoll were gathered the members of the “Big Bug Club.”

Fig. 186. A Section through the Completed Cave.

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