THE LOCOMOTIVE. 



the boiler, and that steam must be twice discharged from each 

 cylinder through the blast ppe. It follows, that to accomplish the 

 speed above mentioned, the boiler must supply to the cylinders 



Fig. 12. 



eigiit hundred measures of steam of the requisite pressure per 

 minute. The valves which admit this steam to each cylinder must 

 be opened four hundred times per minute, as must also both valves 

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