00 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE VOL. 27 



tiou of the exhaust steam would be condensed and be available for use in the 

 boiler again. The gasoline vapor had many advantages over the alcohol; but it 

 was at first possible to evaporate only 120 cu. cm. of gasoline in a minute. 



In the experiments that were made at this time (March 9) with gasoline, 

 the main object in view was to obtain a smooth blue flame at 10 pounds pressure. 

 There had been failures to accomplish this, owing to the high boiling point of 

 the liquid, and while the work was in progress it was still evident that the prob- 

 lem of 1 he boiler and the flame which was to heat it had not been solved. A Prouy 

 brake test gave, at 130 pounds pressure, 1.1 II. P. with about 1000 revolutions 

 of the propellers; but this was with steam supplied from the boiler of the sta- 

 tionary shop engine. 



On April 1, 1894, the following record was made of the condition of Aero- 

 drome No. 5 : 



' ' The wings, the tail, and the two 80 cm. propellers, as well as the two smaller 

 propellers, are ready. The cylinders, gear, pump, and every essential of the 

 running gear, are in place. The boilers, separators, and adjuncts are still under 

 experiment, but may be hoped to be ready in a few days. At present, the boilers 

 give from 450 to 600 grammes of mixed steam and water per minute. With 130 

 pounds of steam, the engine has actually developed at the brake, without cut- 

 off, considerably more than 1 H. P., so that it may be confidently considered that 

 at 150 pounds, with cut-off, it will give at least 0.8 H. P., if it works proportion- 

 ately well." 



The delays incident to the accomplishment of the work in hand were always 

 greater than anticipated, as is instanced by the fact that it was the latter part 

 of September before the work was actually completed. The greater part of this 

 delay was due to the uecessity for a constant series of experiments during the 

 spring and summer to determine the power that it was possible to obtain with 

 the various styles of boilers, aeolipiles, and gasoline burners. 



While No. 5 was thus under construction, new and somewhat larger engines 

 had been built for No. 4, the work on them having been begun in January. The 

 cylinders of these engines, which are more fully described in connection witli 

 Aerodrome No. 6, were 2.8 cm. in diameter, with a 5 cm. stroke, each cylinder 

 thus having a capacity of 30.8 cu. cm., which was an increase of 36 per cent 

 over that of t lie old brass cylinder engines, which had previously been used on 

 No. 4. On April 28, under a pressure of 70 pounds, these engines drove the 

 two 60 cm. propellers at a rate of 900 R. P. M., and lifted on the pendulum nearly 

 40 | iev cent of the total flying weight of Aerodrome No. 4, which was now ap- 

 proximately 5 kilos. A trial was made at Quantico in the latter part of May, 

 which is described in Chapter TX. It is only necessary to mention in this con- 



i (ion that there was a great deal of trouble experienced with the alcohol aeo- 



lipile, the flame being extinguished in the moderate wind to which the aero- 



