as to conform to the required shape.  It should so remain at least twenty-four hours before being fixed to the model.  All the spars are attached by glue and neat cross bindings.  If the central rod be of triangular instead of T section, the join can be made more neatly.  The same remarks apply to the two 9 and 10 inch struts at the propeller end of the rod, which have to withstand the pull of the rubber motor on PPl.  These two pieces will have a maximum strength and minimum weight if of the T section used for the rod.  If the work is done carefully, 1/4 inch each way will be sufficient.

Main Plane and Elevator.—­The framework of each plane is simply four strips of satin walnut or other suitable wood, 1/4 inch broad and 1/16 inch or even less in thickness for the main plane, and about 1/16 by 1/16 inch for the elevator.  These strips are first glued together at the corners and left to set.  The fabric (Hart’s fabric or some similar very light material) is then glued on fairly tight—­that is, just sufficiently so to get rid of all creases.  The main plane is then fixed flat on to the top of the central rod by gluing and cross binding at G and H. (A better but rather more difficult plan is to fasten the rectangular frame on first and then apply the fabric.) The same course is followed in dealing with the elevator, which is fixed, however, not to the rod, but to the 4-inch horizontal spar, HS1, just behind it, in such a manner as to have a slight hinge movement at the back.  This operation presents no difficulty, and may be effected in a variety of ways.  To set the elevator, use is made of the short vertical mast, M1.  A small hole is pierced in the front side of the elevator frame at Z, and through this a piece of thin, soft iron wire is pushed, bent round the spar, and tied.  The other end of the wire is taken forward and wrapped three or four times round the mast M1, which should have several notches in its front edge, to assist the setting of the elevator at different angles.  Pull the wire tight, so that the elevator shall maintain a constant angle when once set.  H H1 is a piece of 25 to 30 gauge wire bent as shown and fastened by binding.  It passes round the front of the rod, in which a little notch should be cut, so as to be able to resist the pull of the twin rubber motors, the two skeins of which are stretched between H H1 and the hooks formed on the propeller spindles.  If all these hooks are covered with cycle valve tubing the rubber will last much longer.  The rubber skeins pass through two little light wire rings fastened to the underside ends of HS2. (Fig. 133.)

The front skid or protector, FS, is made out of a piece of thin, round, jointless cane, some 9 inches in length, bent round as shown in Fig. 134, in which A B represents the front piece of the T-shaped rod and x y z a the cane skid; the portion x y passing on the near side of the vertical part of the T, and z a on the far side of the same.  At E and F thread is bound right round the rod.  Should the nose of the machine strike the ground, the loop of cane will be driven along the underside of the rod and the shock be minimized.  So adjust matters that the skid slides fairly stiff.  Note that the whole of the cane is on the under side of the top bar of the T.