of the large one, a contract was entered into on February 23, 1900, which specified that the engine should be delivered by April 1, with a penalty for any delay beyond that date. The frame for this quarter-size model was immediately begun and extra workmen were employed for work on it in order that its construction should in no way delay the completion of the large machine. The decision to construct this quarter-size model of the large aerodrome had been made on the assumption that, since it was to be one-sixteenth the weight of the large machine, and therefore much heavier in comparison to its size than the steam models Nos. 5 and 6, it would, therefore, not need to be so carefully constructed in order to obtain sufficient strength. But when construction was actually begun it was found not only that the simpler and less expensive methods which it had been proposed to use in joining its frame together resulted in a weak construction, but also that the time consumed in tinkering up the imperfections in the joints more than counterbalanced the extra time which would have been required to make the joints in the best manner from the beginning. Before going very far it was therefore decided to make the joints by following the same process which had been developed in the construction of the previous models. The frame was accordingly built in the most substantial manner, and when guyed by a system of guy-wires similar to that employed for the large machine it was found to be exceedingly stiff, in fact very much stronger and stiffer than the frame of any of the preceding models. In originally planning the model the intention was to make all its linear dimensions exactly one-fourth those of the large aerodrome. Before the designs were completed, however, it was seen from the previous experience with the steam-driven models that instead of the 62.5-cm. propellers, which a strict adherence to the quarter-size plan would demand, it would be necessary to use propellers which were at least one metre in diameter. Moreover, as the small engine would be more than one-fourth the size of the engine under construction for the large aerodrome, a departure from the scale in the case of the transverse frame would be necessary. The designs were therefore altered so as to admit of using the larger propellers, and the tubes which formed the front of the transverse frame were bent, as shown in the plan photograph, Plate 70, in order to give a large enough space for properly mounting the engine. The frame with these modifications was completed in June, 1900, but no engine was ready for it, as the builder had failed to fulfill his contract for either the large or the small engine, although several trips to New York had been made to expedite their successful completion. [p228]