The groove in the exact center of the running surface should now be cut in, which is made about ¹⁄₈ in. deep, and ³⁄₈ to ¹⁄₂ in. in width. A grooving plane is most convenient, but a small gouge, if carefully used, will do as well. The groove should run from the heel to the beginning of the bend.
To finish the ski, sandpaper top and bottom smooth, and rub down with linseed oil to which little paraffin, or beeswax, has been added. The running surface of the ski should be finished with oil and waxed, and it is an advantage that the entire ski be finished in the same manner, as less snow will stick to the tops than if varnish is used. The experienced skier is more concerned about the running qualities of his skis than the finish, but the novice is more likely to be attracted by fancy implements. When varnished tops are wanted, a glossy and durable surface is obtained by brushing on a couple of coats of good spar varnish.
A tube, or cake, of wax should be carried by every skier, for the running surface must have numerous coatings that the snow may not stick to the wood. Both paraffin and beeswax are suitable, and the skier may use one of the several good preparations put up in tubes and in cakes, or melt up his own, as preferred. A good cake, or hard, wax is made by melting up 10 oz. of beeswax with 5 oz. of rosin. When melted, stir in 1 oz. of turpentine and pour in small boxes to form cakes of convenient size.
The running surfaces are often waxed by rubbing the wax on and then going over the surfaces with a hot flatiron. This is a good method, providing only a sufficient quantity of wax has been applied. A too liberal application of wax cannot be called a disadvantage when running downhill, but it will make the runners so slippery that climbing uphill is difficult.
Filling Toy Rubber Balloons with Hydrogen
Apparatus for Filling Toy Rubber Balloons with Hydrogen Gas to Make Them Fly to a Great Height
Any boy can easily convert a toy rubber balloon into a real flier by constructing the simple device shown in the illustration for filling it with hydrogen. Procure a clay pipe and break off the stem near the bowl. Bore a hole in a cork, or preferably a rubber stopper, selected to fit some bottle and insert the smaller end of the pipestem in the hole. As the stem tapers, if the hole has been made for the smaller end, a tight fit is assured by simply pressing the stem well into the cork. Tie the open end of the stem on the balloon tightly over the larger end of the pipestem, and have ready a thread to tie the stem of the balloon when it is filled.
Procure from a local drug store 1 oz. of hydrochloric acid. Place some nails, or better still, a few strips of zinc, in the bottle and cover them with a little water, then pour a small quantity of the hydrochloric acid into the bottle and assemble as shown in the illustration. In a few minutes hydrogen gas will be given off, and if the joints are tight, the balloon will begin to fill. After it has expanded as much as it will stand without breaking, tie the end with the thread, and cut off any parts of the mouthpiece that may weigh it down. If sufficient gas has been passed into the balloon it will rise to the ceiling. Balloons filled in this manner have risen to a height of several hundred feet.
Caution: Do not allow the hydrochloric acid to come in contact with the skin or clothing, as it may cause frightful burns. Do not under any circumstance fill the balloon near a flame or allow fire to come near the bottle.—Contributed by Ralph C. Jenkins, Manchester, Vt.