g8 SMITHSONIAN' CONTRIBUTIONS TO KNOWLEDGE VOL. 27 



The engines in use at this time were the small steel cylinders described 

 above, which were mounted on the cross-frame, and drove the propellers directly. 

 These engines were capable of delivering to the propellers, as had been proved 

 by repeated tests, at Least 0.66 brake horse-power. 



The boiler consisted of two inner coils and an enveloping outer coil, loosely 

 wound and connected in series. The inner coils, each of which had about 17 

 turns of 8 mm. diameter, 0.2 mm. thick tubing, developed about 80 per cent of 

 the steam; the outer coil of 8 turns, while not exactly useless as a steam gener- 

 ator, afforded an efficient means of fastening the smoke-stack and cover of the 

 boiler, and for attaching the latter to the midrod. This boiler was externally 

 30 cm. long, 16 cm. wide, and 10 cm. deep, weighing with its cover approximately 

 650 grammes. The stack for the burnt gases, into which exhaust steam was led 

 from a central jet, was about 1 foot long. At best this boiler was capable of 

 developing slightly over 100 pounds of steam. 



The separator was of the form last described, except that the steam dome 

 had been moved toward the front, to prevent the jerk of the launching car in 

 starting from causing water to be pitched over into the engines. It was con- 

 structed of sheet aluminum-bronze, and weighed, together with its pump, 580 

 grammes. The pump, which was double-acting and fitted with ball valves, was 

 capable of discharging 4.5 grammes of cold water per stroke, its efficiency being 

 only about one-half as great with hot water. 



The gasoline burner, which had been finally adopted in place of the alcohol 

 aeolipiles, had now been perfected to the form in which it was finally used. Two 

 Bunsen burners of special construction were provided with gasoline gas by the 

 heat of an intermediate accessory burner, which played upon a coil to which all 

 three burners were connected. Gasoline was furnished from a tank made of 

 aluminum-bronze, under an air pressure of about 20 pounds, the fluid being un- 

 der the control of a screw stop-cock. This tank, which was capable of holding 

 100 to 150 cu. cm. of gasoline, weighed 180 grammes, and the burners with an 

 outer sheathing weighed 302 grammes. 



It was calculated that about :5300 cu. cm. (201 cu. in.) of air space would be 

 required 1<> float the aerodrome in water, and this was supplied by an air cham- 

 ber, having a capacity of 2700 cu. cm. (165 cu. in.), which could lie shifted to 

 adjust the longitudinal equilibrium of the aerodrome, and about 900 cu. cm. (.V) 

 cu. in.) of space in the gasoline tank and the midrod. The reel and float, which 

 served to indicate the location of the aerodrome, if for any reason it should be 

 submerged, were in one piece, and so moored that there was no danger of fouling 

 the propellers. 



The total weight of the aerodrome was about 6 kilogrammes (13.2 lbs.), or, 

 with a maximum quantity of fuel (850 cu. cm. of water, 150 cu. cm. of gasoline), 



