To make the very extensive experiments necessary to determine these propositions conclusively would have required much more time than could at this period be spared from the actual constructional work on the aerodrome. Nevertheless, 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 necessary strength to the frame of the large aerodrome. This plan of construction was, therefore, definitely adopted, and as a result of later experience the system 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 requiring great strength to enable it to withstand the strains, both torsional and direct, 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; but 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›, ‹E›, ‹F›, ‹G›, ‹H› and ‹I› designate parts of the main frame, ‹A› and ‹H› being the rear and front midrods, respectively, to which the wings were to be attached. ‹B› and ‹I› are curved extensions of the starboard main tube, the port main tube being exactly similar, and ‹C›, ‹D›, ‹E›, ‹F› and ‹G› are cross-tubes which connect the midrods to the port and starboard tubes. ‹R› 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 [p168] transverse frame are joined together by the “bed plates” ‹L›, which are of I-beam section, and have mounted on their outer faces the bearings which support the propeller shafts. At ‹V› are bevel gears mounted on the propeller shafts, which are driven by co-acting bevel gears, ‹M›, mounted on the outer ends of the transmission shafts, ‹O›, the latter being at this point firmly supported in bearings mounted on the inner faces of the bed plates and steadied by the intermediate bearings, ‹N›. The two transmission shafts are seen to be not in line, the rotary cylinder engine that was then under construction requiring this arrangement. The bed plates, ‹L›, are further stiffened by the brace tubes, ‹K›, and the transverse frame is braced against the thrust of the propellers by the tubes ‹J›. The four tubes, ‹P›, unite at their upper ends to form what