240 



AERONAUTICS. 



How to construct an artificial Wave Wing on the Insect 

 type. — The following appear to me to be essential features in 

 the construction of an artificial wing : — 



The wing should be of a generally triangular shape. 



It should taper from the root towards the tip, and from 

 the anterior margin in the direction of the posterior margin. 



It should be convex above and concave below, and slightly 

 twisted upon itself. 



It should be flexible and elastic throughout, and should 

 twist and untwist during its vibration, to produce figure-of-8 

 curves along its margins and throughout its substance. 



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 h) 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 con- 

 sist 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 {ghi 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 ab of 

 fig. 124. 



To this I add successive layers (i, h, g, /, e) of some flexible 

 material, such as parchment, buckram, tracing cloth, or even 



