32 Locomotive Steam Engines. 



Thursday, March 5th, 1868. 



The Society held its Fortieth Meeting at Mr. Bull's House. 

 Matheson and Currie were elected members. 

 A speck of Nutmeg was exhibited by Mr. Farrar. 



Welch then read a Paper on 



LOCOMOTIVE STEAM ENGINES. 



In this paper the different parts of a Locomotive and the duties 

 they respectively fulfil were first described, and then the various 

 improvements and inventions in use on the best engines were 

 explained. 



As diagrams and models are necessary in order that the com- 

 plicated machinery of the Locomotive may be fully understood, 

 this abstract is limited to an explanation of some of the principal 

 improvements. 



Formerly, coke alone was used for the fire, on account of the 

 smoke coal created, but now coke is found to be too expensive, 

 and is only used on the Underground, and a few other Railways, 

 where a total absence of smoke is desired ; many plans therefore 

 have been devised for consuming the smoke, one is to divide the 

 fire-box into two furnaces by a vertical longitudinal partition con- 

 taining water, and communicating with the boiler, these furnaces 

 are fed alternately, and the gases from each mix in a chamber 

 termed the " combustion chamber," where the smoke is consumed 

 before it enters the tubes. Another plan is to build inside the 

 fire-box an arch of fire-brick, this gets intensely heated and causes 

 all the smoke to be consumed. 



An improved form of safety valve was also noticed, one invented 

 and patented by Mr. Ramsbottom, the Locomotive Engineer of the 

 London and North Western Railway, it has two valves almost 

 close together which are kept down by a single bar, this bar is 

 loaded by a strong spring placed between the two valves, so that 

 if the driver tries to weight the lever it will press down one valve, 

 and using it as a lever, will raise the other. 



The regulator valve or tap for admitting steam to the cylinders 

 can be arranged in many different forms, but the one most largely 

 used now consists of a chest termed the regulator valve chest, 

 communicating with the boiler, and from which two pipes go to 

 the cylinders, the distance between the mouths of the two being 



