Now for the post. This should be at least twenty feet long, so as to leave about fifteen feet projecting when set upright in the hole. The butt should be left very large, as is done with ordinary wooden gate-posts, and the whole affair ought to be made of thoroughly seasoned wood. Unless this is the case, it is sure to rot, and then down it comes some day, when least expected. Triangular steps should be nailed upon opposite sides, like those on railway signal-posts, as otherwise the daily task of removing and replacing the ropes will be very irksome.
Get a blacksmith to make a stout iron pin, such as is shown at [a], having a projecting shoulder, to prevent it from entering too far into the wood. He should also make a strong iron collar to put over the top of the pole, as is seen at [b], where the pin is also shown fixed. The last piece of blacksmith’s work is an iron disc, having a cap or thimble in the middle, which is intended to receive the iron pin, and to enable the disc to spin round freely. Four holes are bored through the edge of the disc, as seen at [c]. Purchase four iron S hooks, and the same number of swivels, and good store of well-made half-inch rope, and the machine may then be set up.
First char carefully the whole of the butt that is to enter the ground, and for about six inches above, in order to prevent the wood from being injured by wet. Place it upright in the hole, testing it by a plumb-line tied to the top, and fill in the hole with earth, pounding it down firmly with a heavy rammer. You cannot be too careful about this process, and the apparatus should not be used until the earth has had time to settle. While waiting for this operation, cut the rope into appropriate lengths, and fasten one end of each rope to a swivel, and the other to the centre of a stout bâton of elm or oak wood, about eighteen inches long. Unless you are very sure of your powers of splicing ropes and making “eyes,” let the ropemaker do this for you, as it is a most important operation, and involves the security of the gymnast in no slight degree. It is necessary to have swivels, as the ropes would otherwise become so twisted as to lose their freedom of play, or even to weaken their structure. These preparations being completed, mount the post by the steps, taking the cap with you, grease the pin well with an end of tallow-candle, and slip the cap upon it, taking care to spin it well in order to assure yourself that all is right. Hang the swivels to the circular plate by means of the S hooks, one curve of which passes through the hole in the plate, and the other through the loop in the swivel.
The ropes should be just so long that when they hang loosely along the pole the cross-bar should be two feet from the ground. As, however, new ropes stretch in a wonderful manner, it is needful to allow considerably for this property.
One thing more is needed, and then the whole apparatus will be complete.
Measure the greatest distance which can be reached by the feet of any one swinging round by the ropes, and about one yard beyond that line erect a slender pole nearly as high as the central post, having pegs driven at intervals of four inches. This is intended to aid the learner in leaping, and the mode by which this object is accomplished is seen in [fig. 1].
