166 



FERGUSON'S LECTURES. 



At the beginning of the last century, the atmospheric engine 

 r had made considerable progress in the mining districts, and in 

 1718, the patentees agreed to erect an engine for the owners of a 

 colliery in the county of Durham, where several hundred horses 

 had previously been employed. Mr. Henry Beighton, who was 

 engaged as an agent in this concern, materially improved the en- 

 gine by making it self-acting, and divesting it of nearly all the 

 complicated machinery which had been previously employed for 

 that purpose. 



We come now to a new and distinct era in the history of this 

 important invention ; and in noticing the labours of Mr. Watt, 

 we may almost speak of his engine as the gigantic offspring of a 

 hand giving birth to an automaton no less powerful than that of 

 the fabled enchanters of the " olden time." 



The above diagram will best explain the single acting engine 

 first invented by Mr. Watt. 



A is the steam pipe connecting the boiler, in which steam 

 is generated, with the lower part of the steam cylinder B, 

 and a is the cock for admiting or shutting off the steam, there- 

 fore called the steam cock or valve. C is the piston moving in 

 an air-tight manner upwards and downwards in the steam cy- 

 linder. D the piston rod, the upper end of which is connected 

 to one end of the engine beam. E a cock and pipe leading to 

 an elevated cistern, by which a little water can be discharged on 

 the top of the piston to keep it air-tight. F F section of the 



