23 BUI,LETIN 173, U. S. NATIONAL MUSEUM 



a regulator valve worked by hand, steam from the boiler was ad- 

 mitted into a receiver and allowed to blow through it till the air had 

 been expelled; then the supply of steam was cut off and cold water 

 from a cistern above was turned on to the receiver which acting as 

 a surface condenser, condensed the steam, so forming a partial vacuum 

 into which the water rose from the suction pipe, the delivery orifice 

 being at the same time sealed by its valve; the entering water fur- 

 ther assisted in this condensation. Steam was again admitted, and 

 by its pressure forced the water in the receiver out through the 

 delivery valve and pipe, the suction pipe in the meantime being closed 

 by its non-return valve." 



References, The Miner's Friend^ 1702 ; Philoso'phical Transactions^ 

 vol. 21, 1699. 



NEWCOMEN ENGINE, 1712 



Plate 11 



U.S.N.M. no. 308451 ; print from an engraving of 1717 ; gift of the Newcomen 

 Society ; photograph no. 1 7872. 



This engraving is made from a drawing of 1717 by Henry Beighton, 

 presumably from his own measurements of the engine erected by 

 Thomas Newcomen near Dudley, England, in 1712. It is the oldest 

 present record of a Newcomen engine, and the original engine is 

 believed to have been the first one actually built by Newcomen. 



The engine shown has a vertical cylinder directly over the center of 

 a bricked-over hemispherical boiler. The cylinder is hung between 

 two heavy wooden beams, which, in turn, are supported about midway 

 of the height of two thin, wide, brick columns, one on each side of 

 the boiler. One column is hollow and serves as a chimney for the 

 boiler furnace; the other column supports the bearings upon which 

 the beam or great lever of the engine rocks. 



The cylinder is open at the top, and the piston rod extends upward, 

 terminating in a hook. A flexible chain from the hook connects it 

 to the end of the engine beam, which is arched so that the point of 

 contact of the chain is always directly over the center of the piston. 

 The pump cylinder is located under the opposite end of the beam, and 

 the pump rod is similarly connected to the beam by chain. The pump 

 rod is shown extending down into the open mouth of a mine pit, over 

 wliich is erected a windlass for raising and lowering men and ore. A 

 smaller arched head or sector on either side of the center of the beam 

 between tlie center and the end of the beam operates an auxiliary pump 

 and the plug rod that actuates the valves. 



To one side and above the cylinder is a cistern that holds the water 

 for injection into the cylinder for condensing purposes. (See the 

 Newcomen engine, p. 30, for general explanation of the operation.) 



