The location of the struts in the plane is illustrated in Fig. 3. The two in the centre are two feet apart and the others respectively 4 feet 6 inches and 9 feet on either side. The struts on the upper plane are placed so that the projections come above the horizontal members. Those on the lower plane are placed just the opposite, that is so that they come on the under side.
They are fastened with one or two small wire nails and then secured by means of a clamp. Two dozen clamps are required. They are bent out of a strip of sheet brass one sixteenth of an inch thick, 3 7/8 inches long and 1 inch wide. The ends are rounded and a 1/4 inch hole located and bored in each as in Fig. 4.
[Illustration: Fig. 3.—Position of Struts.]
The clamp also serves to protect the under side of the beam from the action of the nuts on the ends of the eyebolts. The method of fastening the clamp is detailed a little later.
*Stanchions*. The planes are separated by twelve stanchions, four feet long and 7/8 of an inch in diameter.
They are rounded and smoothed up so that the ends will fit snugly into the socket illustrated in Fig. 6. These sockets may be purchased¹ already bored and finished or can be procured at a foundry. They are preferably made of aluminum which metal is at once light and strong but brass or even iron may be used if it is necessary to avoid expense.
[Illustration: Fig. 6.—Stanchion socket.]
There are other methods of joining the stanchions to the beams but the use of the socket is recommended because it is the strongest method and also permits the glider to be readily taken apart.
The base of the socket is 3 1/4 inches long, 1 1/4 inches wide and 1/4 of an inch thick. The cup has an internal diameter of seven eighths of an inch and an outside diameter of one inch and one quarter. It is one inch high above the base. Two 1/4 inch holes are bored 1 7/8 inches apart in the base. Two smaller holes 1/8 inch in diameter are bored 7/16 inch nearer the ends of the base than the larger holes.
*The wooden pattern* is made from the dimensions indicated in Fig. 6. It is thoroughly smoothed up by rubbing with sand paper and then given a coat of shellac. All parts should have a very slight taper towards the top so that the pattern may be withdrawn easily from the sand mould.