168 



Practical at- 

 tempt lo overr- 

 come them. 



Weight, di- 

 mension!*, and 

 power of th« 



wing. 



Priaciplos of 

 the construc- 

 tion. 



Diagonal bra- 

 cing. 



OX AERIAL NAVIGATION, 



necessary obstacles to tlie cnneut,) I cannot better explain 

 than by dc-^cribinga wing, which has been constructed with 

 a view to overcome them. 



Fig. 4 represents the shape of the cloth, with a perspec- 

 tive view of the poles upon whicii it is stretched with perfect 

 ti<>htness. Upon the point where the rods A and B inter-^ 

 sect is erected an oval shaft ; eiubracing the two cross poles 

 by a slender iron fork ; for tiie purpose of preserving their 

 strength uninjured by boiing. To this shaft are braced the 

 ends of the pole R, so as to give this pole any required de- 

 gree of curvature. The pole A is strung like a common 

 bow to the same curve as the pole B ; and is only connected 

 with the upright shaft by what may be caUed a check brace ; 

 which will allow the hinder end of this pole to heel back to a 

 certain extent, but not the fore end. The sliort brace pro- 

 ducing this effect is shown in fig, 4. Fig. 5 exhibits the fel- 

 low wing to that represented in fig. 4, erected upon a beam* 

 to which it is so braced, as to convert the whole length of it 

 into a hinge. The four braces coming from the ends of this 

 beam are shown : two of them terminate near the top of the 

 centre of the other shaft ; the others are inserted into the 

 point C,fig. 4, of the bending rod. A slight bow, not more 

 than three-eighths of an inch thick, properly curved by its 

 •trlng, and inserted between the hinder end of the pole Ay 

 and the curved pole C, completes the wing. 



This fabrick contained 54 square feet, and weighed only 

 eleven pounds. Although both these wings together did 

 not compose more than half the surface necessary for the 

 support of a man in the air, yet during their waft they lifted 

 the weight of nitie stone. The hinder edge, as is evident 

 from the construction, .being capable of giving way to the re- 

 sistance of the air, any degree of obliquity, for the purpose 

 of a propelling power, may be used. 



r am the more parlicularin describing this wing, because 

 it exeifiplifies almost all the principles that can be resorted 

 to in the construction of surfaces for aerial navigation. 

 Diagonal bracing is the great principle for producing 

 strength without accumulating weight; and, if performed 

 by thin wires, looped at their ends, so as to receive several 

 laps of cordage, produces but a trifling resistance in the 



air, 



