NO. 3 ^ANGLE'S MI'.Moli; ON MECHANICAL FLIGHT 107 



These results are fairly well summarized in the following general state- 

 ments: First, that the coefficient of resistance increases to some degree as the 

 size of the wire is decreased; second, that in the ease of wires of the size which 

 it was expected to use, and at approximately the soaring speed of the aero- 

 drome, the resistance is certainly not greater than 75 per cent, and more prob- 

 ably less than 50 per cent of the resistance encountered by a flat surface of the 

 same projected area; third, that the coefficient of resistance did not seem to be 

 increased by the vibration of the wires. On the contrary, it was noted during 

 the experiments thai when they reached a speed which just caused them to 

 " sing," there was a marked diminution in the resistance. This statement is 

 made, however, witli some reserve, for it is probable that the singing of the 

 wires was due to vibration in the horizontal plane, and it is not definitely known 

 what the effect would be of vibration in the vertical plane. 



To make the very extensive experiments necessary to determine these prop- 

 ositions conclusively would have required much more time than could at this 

 period be spared from the actual constructional work on the aerodrome. Never- 

 theless, the data did seem to indicate that it was at least not unwise to employ 

 the extensive system of guying which had been planned in order to give the nec- 

 essary strength to the frame of the large aerodrome. This plan of construction 

 was, therefore, definitely adopted, and as a result of later experience the sys- 

 tem of guying was still further extended, 



As the transverse frame had to be made comparatively rigid in order to 

 prevent undue binding of the bearings of the transmission and propeller shafts, 

 it was necessary to make it intrinsically stronger and, therefore, heavier in 

 proportion to its size than the main frame. The main frame, although requir- 

 ing great strength to enable it to withstand the strains, both torsional and di- 

 rect, which were imposed upon it by the weights which it supported, did not 

 need excessive rigidity, and could, indeed, be distorted an appreciable amount 

 without danger of any serious effect on the action of the wings or rudder; lint 

 even a small amount of distortion in the transverse frame might easily cause 

 such friction at the bearings of the shafts as to absorb fifty per cent or more of 

 the engine power. 



In the photographs, Plates 45 to 48, which show the actual condition of the 

 frame on January 31 and February 1, 1900, the letters A, B, C, D, K. F. G, U 

 and I designate parts of the main frame, A and H being the rear and front mid- 

 rods, respectively, to which the wings were to he attached. 7? and I are curved 

 extensions of the starboard main tube, the port main tube being exactly sim- 

 ilar, and C, D, E, F and G are cross-tubes which connect the midrods to the port 

 and starboard tubes. B is the front main tube of the transverse frame, the rear 

 main tube being exactly similar, and both being connected to the main tubes 

 of the main frame where they cross them. The ends of the main tubes of the 



