36 SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE . VOL. -7 



10 square feet afforded bj them could safely be depended upon to provide steam 

 for a 1 horse-power engine. As far as fuel consumption was concerned, the rate 

 of evaporation was about 15.6 pounds of water per pound of gasoline, all of 

 which was satisfactory. 



The burner originally designed for use in connection with the " beehive " 

 boilers, consisted of a small tank in which a quantity of gasoline was placed, the 

 space above being filled with compressed air. Rising from the bottom of this 

 tank was a small pipe coiling back and down and ending in an upturned jet from 

 which the gas generated in the coil would issue. The burner thus served to 

 generate its own gas and act as a heater for the boilers at the same time. 



In the construction of Aerodrome No. 0, four of the " beehive " coils were 

 placed in a line fore and aft. The fuel tank was located immediately back of the 

 rear coil and consisted of a copper cylinder 11 cm. in diameter and 9 cm. long. 

 The engines were placed immediately in front of the coils, all the apparatus 

 being enclosed in a light framing, as shown in the photograph (Plate 10). 



Kxtending front and back from the hull were the tubes for supporting the 

 wings and tail, each one metre in length. The cross-framing for carrying the 

 propeller shafts was built of tubing 1.5 cm. diameter, and the shafts themselves 

 were of the same size. The ribs of the hull were rings made of angle-in ms 

 measuring 1.50x1.75 cm., which were held in place longitudinally by five 0.7 cm. 

 channel bars. 



As it had been learned in the preliminary experiments with the model " bee- 

 hive " boiler that the heated water would not of itself cause a sufficiently rapid 

 circulation to be maintained through the tubes to prevent them from becoming 

 red hot, two circulating pumps were added for forcing the water through the 

 coils of the two forward and two rear boilers respectively, the water being taken 

 from the lower side of the drum and delivered into the bottom of the coils, which 

 were united at that point for the purpose. A worm was placed upon each of the 

 propeller shafts, just back of the engines, meshing in with a gear on a crank- 

 shaft from which the pumps were driven. This shaft rotated at the rate of 1 to 

 l!4, so that for L200 revolutions of the engine, it would make but 50, driving a 

 single-acting plunger l."2 cm. in diameter and 2 cm. stroke. 



Apparently all was going well until I began to try the apparatus. First, 

 there was a difficulty with the burner, which could not be made to give forth the 

 relative amount of heat that had been obtained from the smaller model, and 

 steam could not be maintained. With one " beehive " connected with the com- 

 pound engine, and a 70 cm. propeller on the shaft, there were about lT>0 turns 

 per minute for a space of about .")() seconds, in which time the steam would fall 

 from 90 pounds to 25 pounds, and the engine would stop. Then, as we had no 

 air-chamber on the pumps at the time, they would not drive the water through 

 the coils. Subsequent experiments, however, showed that the boilers could be 



