WILLIAM SIEMENS, F.R.S. 153 



number of blowers in a series of gas-producers. A valve <i is 

 provided in the brunch pipe E, for shutting off the steam from the 

 lilu\\i-r \\lr ii not in use ; and a small tap J serves for discharging 

 any water that may collect in the pipe by condensation of the 

 steam. 



The advantages found to result from applying these blowers to 

 gas-producers are, that coal dust of the most inferior description 

 ran l>e used, and that the gas production of each producer in con- 

 suming small fuel is raised from l tons to 8 tons of gas per 24 

 hours ; while at the same time the quality of the gas is improved, 

 owing to the generation of hydrogen from the steam which enters 

 intermingled with the air. 



These applications of the improved steam jet suffice to illustrate 

 its scope and value. Other useful applications will readily suggest 

 themselves, where work may be accomplished by exhausting or 

 compressing air or gases. 



In conclusion the author would remark that although the steam 

 jet is not a new mechanical agent, and has been applied before for 

 various purposes and in a variety of forms, yet the mechanical 

 conditions under which it is capable of developing the greatest 

 amount of useful effect have not previously been laid down or 

 practically realised in such a way as to produce results at all 

 comparable with those obtained from a steam-engine working an 

 air-pump ; but this it is maintained a steam jet may do, if care be 

 taken that the available elastic force is changed into onward 

 motion of the combined jet, and again into onward pressure, with- 

 out undue loss of effect by eddies or by development of sound or 

 heat, which have constituted the principal results in the case of an 

 ordinary steam jet. 



The PRESIDENT said he had been led to investigate the subject of 

 the steam jet in consequence of having been engaged in con- 

 structing a circuit of pneumatic despatch tube for the Central 

 telegraph office in London ; the tube itself had cost 3000, and 

 fully as much had been spent on the engine and air pump. As 

 there was moreover great difficulty in finding room for this 

 machinery in so crowded a locality, it had occurred to him that a 

 more direct means of propelling the piston carriers through the 

 tube would be a matter of some importance ; and in considering 



