Such a wing is represented at fig. 122, p. 239. If the wing is in more than one piece, joints and springs require to be added to the body of the pinion. In making a wing in one piece on the model of the insect wing, such as that shown at fig. 122 (p. 239), I employ one or more tapering elastic reeds, which arch from above downwards (_a b_) for the anterior margin. To this I add tapering elastic reeds, which radiate towards the tip of the wing, and which also arch from above downwards (_g_, _h_, _i_). These latter are so arranged that they confer _a certain amount of spirality_ upon the wing; the anterior (_a b_) and posterior (_c d_) margins being arranged in different planes, so that they appear to cross each other. I then add the covering of the wing, which may consist of india-rubber, silk, tracing cloth, linen, or any similar substance. If the wing is large, I employ steel tubes, bent to the proper shape. In some cases I secure additional strength by adding to the oblique ribs or stays (_g h i_ of fig. 122) a series of very oblique stays, and another series of cross stays, as shown at _m_ and _a_, _n_, _o_, _p_, _q_ of fig. 123, p. 241. This form of wing is made to oscillate upon two centres viz. the root and anterior margin, to bring out the peculiar eccentric action of the pinion. If I wish to produce a very delicate light wing, I do so by selecting a fine tapering elastic reed, as represented at _a b_ of fig. 124. To this I add successive layers (_i_, _h_, _g_, _f_, _e_) of some flexible material, such as parchment, buckram, tracing cloth, or even paper. As the layers overlap each other, it follows that there are five layers at the anterior margin (_a b_), and only one at the posterior (_c d_). This form of wing is not twisted upon itself structurally, but it twists and untwists, and becomes a true screw during its action. [Illustration: FIG. 123. FIG. 123.--_Artificial Wing with Perpendicular (r s) and Horizontal (t u) Elastic Bands_ attached to ferrule (_w_). _a_, _b_, Strong elastic reed, which tapers towards the tip of the wing. _d_, _e_, _f_, _h_, _i_, _j_, _k_, Tapering curved reeds, which run obliquely from the anterior to the posterior margin of the wing, and which radiate towards the tip. _m_, Similar curved reeds, which run still more obliquely. _a_, _n_, _o_, _p_, _q_, Tapering curved reeds, which run from the anterior margin of the wing, and at right angles to it. These support the two sets of oblique reeds, and give additional strength to the anterior margin. _x_, Ball-and-socket joint, by which the root of the wing is attached to the cylinder, as in fig. 122, p. 239.--_Original._] [Illustration: FIG. 124. FIG. 124.--Flexible elastic wing with tapering elastic reed (_a b_) running along anterior margin.