The main planes are next to be made. The lower deck of the biplane is of the 1/16 inch whitewood, and the upper one is of the glazed paper upon a skeleton framework of wood. The upright walls are of paper. The wooden deck is to be bent into the proper curve with the aid of steam, and when dry and set in form is to be finished and polished. The frame for the upper deck is made of the thin whitewood, and is held to its position by two diagonal struts of whitewood bent at the ends with steam, and two straight upright struts or posts. It is better to bend all cross-pieces into the curve of the plane with steam, but they may be worked into the curve on the top side with plane and file, and left flat on the lower side. The drawings show full details of the construction, drawn accurately to scale. It is best to glue all joints, and in addition to insert tiny screws, where shown in the plans, at the time of gluing. When all the wooden parts are in place the entire outline of the upper plane and the upright walls is to be formed of silk thread carried from point to point, and tied upon very small pins (such as are used in rolls of ribbon at the stores) inserted in the wood. The glazed paper is put on double, glossy side out. Cut the pieces twice as large (and a trifle more) than is needed, and fold so that the smooth crease comes to the front and the cut edges come together at the rear. The two inner walls should be put in place first, so as to enclose the thread front and back, and the post, between the two leaves of the folded paper. Cutting the paper half an inch too long will give one fourth of an inch to turn flat top and bottom to fasten to the upper and lower decks respectively. The two outer walls and the upper deck may be cut all in one piece, the under leaf being slit to pass on either side of the inner walls. A bit of glue here and there will steady the parts to their places. The cut edges at the rear of the deck and walls should be caught together with a thin film of glue, so as to enclose the rear threads. [Illustration: _A_, _B_, plan, and _C_, section, of steering plane; _H_, section of lower main plane; _L_, wood skeleton of upper plane; _T_, _T_, silk thread; _O_, _O_, posts; _J_, _J_, braces; _E_, rubber strands; _D_, forward hook; _G_, shaft; _F_, thrust-block; _K_, upper plane of paper; _M_, elevation of main planes, from the rear.]