38 SMITHSONIAN CONTBIBTJTIONS TO KNOWLEDGE VOL. 27 



I pass over numerous other experiments, for their only result was to make 

 it clear that the aerodrome, as it had been constructed, could not be made to 

 work efficiently, even it' its great weight had not served as a bar to its flight. It 

 was, therefore, decided to proceed with the construction of another. 



Alter the failure of the first steam-driven model No. 0, which has just been 

 described, subsequent light models were constructed. These, three in number, 

 made with a view to the employment of carbonic acid or compressed air, but 

 also to the possible use of steam, are shown in Plate 10, Nos. 1, 2, 3; on the same 

 scale as the larger model which had preceded them. In describing these, it will 

 be web! to mention constructive features which were experimented on in them, 

 as well as to describe the engines used. 



In No. 1, which was intended to be on about f the linear scale of No. 0, the 

 constructive fault of the latter, that of making the support depend on a too 

 flexible bull, was avoided, and the straight steel tube (" midrod " it will hereafter 

 he called) was carried through from end to end, though at the cost of incon- 

 venience in the placing of the machinery, in what may be called the bull, which 

 now became simply a protective case built around this midrod. The mistaken 

 device of the long shafts meeting at an angle was, however, retained, and the 

 engines first tried were a pair of very light ones of crude construction. 



These were later replaced by a pair of oscillating engines, each 3 cm. di- 

 ameter by 3 cm. stroke, with a combined capacity of 42 cubic cm. and without 

 cut off. The midrod was made of light steel tubing 2 cm. outside diameter. 

 The framing for the hull was formed by a single ring of U section, 8 cm. across 

 ami IS cm. in depth, stayed by five ribs of wood measuring 0.7x0.3 cm. The in- 

 clined propeller shafts, which were connected by a pair of bevel gears as in No. 

 0. were made of tubing 0.5 cm. outside diameter, and were intended to turn pro- 

 pellers of from 40 to 45 em. in diameter. The weight, without engine or reservoir 

 for gas, was 1161 grammes. With a weight equivalent to that of the intended 

 reservoir and engines plus that of the proposed supporting surfaces, the whole 

 weight, independent of fuel or water, was 2.2 kilogrammes. 



The engines, which were not strong enough to sustain a pressure of over 2 

 atmospheres, at an actual pressure of 20 pounds drove the 45 cm. propellers 

 through the long V shafts and lifted only about \ of the flying weighl of the ma- 

 chine. The power developed at the Prony brake was collectively only aboul .04 

 horse-power, giving 1200 turns a minute to two 40 cm. propellers. This was the 

 best result obtained. 



This aerodrome was completed in June, 1892, but changes in the engines and 

 other attempted improvements kept it under experiment until November of that 

 year, when it appeared to be inexpedient fo do anything more wifh it 



Aerodrome No. 2 (see Plate 10), was a still smaller and still lighter construc- 

 tion, in which, however, the midrod was bent (not clearly shown in the photo- 



