82 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 27 



Each wing was attached to the midrod by a single clamp, different forms 

 of which arc shown at /•', G, II, I (Fig. 16). The clamp consisted of two short 

 split tubes, into which the main front ribs were securely clamped by means of 

 screws. They were set at an angle and united to a grooved frame, by which 

 the wings could be readily attached to a second piece clamped about the mid- 

 rod. The tail clamp, like the wing clamp, was composed of two pieces, sliding 

 one upon the other, but as the tail formed a single surface, one part was per- 

 manently attached to it. Clamps F, G were fitted to aerodrome No. 4, and E, 

 1 to No. 5. The wings were set at a diedral angle of about 150°, but as they were 

 not guyed in any way, this angle in flight and under the upward pressure of the 

 air probably became much less. The tail was plane but ribbed like the wings. 



Fig. 16. Wing clamps. 1892-1896. 



In preparing the machine for flight, the wings and tail of No. 4 were set 

 at a very small root angle with the midrod, perhaps not exceeding •'! , but while 

 this angle mighl be maintained at the firmly held root of the wing, it was later 

 seen to be probable that the extremity of the wing was flexed by the upward 

 pressure of the air after launching, though the full extent and evil effect of 

 this flexure was not recognized at the time. In the approximative calculations 

 for " balance," made at this time, the tail was treated as bearing J of the weighl 

 of the aerodrome, as it was \ of the supporting area, for though it was recog- 

 nized that its position in the " lee " of the wings rendered it less efficient, the 

 degree of this diminution of efficiency was not realized. A vertical rudder 

 •Ji ) cm. x 70 cm. (8 in.x28 in.), with an area of 0.14 metres (1.5 sq. ft.) was used. 



