NO. 3 



LANCLF.Y MEMOIB ON' MECHANICAL FLIGHT 



Til 



" Unfortunately there is a limit set to this process of increasing the steam 

 supply, quite aside from conditions inherent in the method. This is due to the 

 fact thai a certain speed of efflux cannot be exceeded without putting the flame 

 out. Suppose, for instance, in Fig. 12, that a gas generated from a liquid is 

 ignited at the end of the Bunsen burner F; then if the velocity of efflux of mixed 



-i J 



Fig. 12 



gas and air in the direction AB from the mouth of F exceeds the velocity of com- 

 bust ion in the direction BA, the flame will obviously be carried away from the 

 mouth of the tube and dissipated. This state of things is actually realized at 

 pressures exceeding about 15 lbs., depending on the degree of mixture of the com- 

 bustible gases used, and therefore on apparently haphazard conditions connected 

 with the jet, the air holes, the air supply, etc. 



P 



c 



Fig. 13. 



" If, however, the velocity of the jet at the point of efflux be checked by an 

 obstruction like a cylinder C, Fig. 13, placed co-axially with the burner tube F, 

 the speed of combustion will no longer be exceeded ( supposing C properly chosen) 

 and flames will then burn from high-pressure gas. In this way flames were 

 maintained generated from alcohol gas at even 40 lbs. and above. 



B 



□ 



Fig. 14. 



" The gas escaping from the Bunsen burner is never sufficiently aerated to 

 burn completely. Otherwise there would (in general) be explosions in the tube 

 F. A part of this air is supplied at the mouth of the boiler B, Fig. 14, and the 

 amount available here will depend on the velocity of the jet F. Hence it does 

 not follow that a high-pressure burner like that in Fig. 11 will supply a pro- 

 portionate amount of heat, since its jet suction is not intense and the combustion 

 within the boiler is incomplete. This difficulty may be remedied by placing 



