40 SMITHSONIAN CONTRIBUTIONS To KNOWLEDGE! VOL. "27 



minute and a half. Bui when a tesl was made, it also was found to be deficient 

 in steaming power even after changes were made in it which occupied much time. 



1">\ the lirst of < Ictober, L892, there had been built one large aerodrome that 

 could not possibly fly, a smaller one, No. 1, on § the linear scale of No. 0, with 

 a pair of engines but no means of driving them, and the still smaller No. 2 with 

 a boiler that was yet untried. 



Aerodrome No. ."> (Plate 10) was an attempt to obtain better conditions than 

 had existed in the preceding model without any radical change except that of 

 moving the cross frame, which carried the engines and propellers, nearer the 

 front of the machine. Instead of the oscillatory engines used up to this time, 

 two stationary cylinder engines, each 2.4 cm. in diameter and 4 cm. stroke, hav- 

 ing a combined capacity of 3(i cu. cm. without cut-off were employed for driving 

 the propellers. The engines, though occasionally run in trials with steam from 

 a stationary boiler, were intended to be actuated either by compressed air or 

 carbonic-acid gas contained in a reservoir which was not actually constructed, 

 but whose weight was provisionally estimated at 1 kilogramme. The weight of 

 the aerodrome without this reservoir was but 1050 grammes, including the esti- 

 mated weight of the sustaining surfaces, which consisted principally of two wings, 

 each about 1 metre in length by 30 cm. in breadth and which were in fact so slight 

 in their construction, that it is now certain that they could not have retained their 

 shape in actual flight. 



The only trials made with this aerodrome, then, were in the shop, of which 

 it is sufficient to cite those of November 22, 1892, when under a pressure of 30 

 pounds, the maximum which the engines would bear, two 50 em. propellers were 

 driven at !»00 revolutions per minute, with an estimated horse-power of 0.07, 

 about 35 per cent of the weight of the whole machine being lifted. This was a 

 much more encouraging result than any which had preceded, and indicated that 

 it was possible to make an actual flight with the aerodrome if the boilers could 

 be ignored, the best result having been obtained only with carbonic acid supplied 

 without limit from a neighboring ample reservoir. 



This aerodrome was also tested while mounted upon a whirling-arm and 

 allowed to operate during its advance through the air. The conclusion reached 

 with it at the close of 1892, after a large pari of the year passed in experiments 

 with carbonic acid gas and compressed air, was that it was necessary to revert 

 to steam, and that whatever difficulties lay in the way, some means must be found 

 of getting sufficient power without the weighl which had proved prohibitory in 



No. 0. 



With this chapter, then, and with the end of the year 1892, 1 close this very 

 brief account of between one and two years of fruitless experiment in the con- 

 struction of models supplied with various motors, subsequent to and on a larger 

 scale indeed than the toy-like ones of india rubber, but not even so efficient as 

 those had been, since they had never procured a single actual flight. 



