688 Transactions of the American Institute. 



are common to other expansion engines. With the exception of the 

 cut-off gear, the engine is a simple slide-valve engine, and can be 

 used as such, should any accident occur to the cut-off. The cut-off 

 itself is also of the simplest possible description, having the least 

 possible number of parts, consistent with a proper performance of 

 its functions. It consists of two cut-off slides, a miniature steam 

 cylinder, and a valve for controlling the admission of steam to the 

 same. This small cylinder, being enveloped in the steam, requir- 

 ing no packing, and having only the weight of the piston to produce 

 wear, is, for all practical purposes, indestructible. The cut-ofl* 

 slides are always balanced when they move, consequently they are 

 not exposed to injurious wear. 



Another advantage of the Babcock & Wilcox engine is that it is 

 easily comprehended by ordinary mechanics. The motions and 

 adjustments are similar to those familiar to any one who under- 

 stands a plain slide-valve engine; and any man who can adjust such 

 an engine pi'operly, can readily adjust this. 



The cut-off valve of this engine presents a convenient means of 

 stopping at any desired point, simply by opening or closing the 

 cut-off valve by hand, as the case may require. The engine may 

 be warmed up, also, without danger of starting, by closing the cut- 

 off valve by hand. In cases where it is desirable to back the 

 engine, a starting bar may be readily shipped, and the engine 

 handled with the same ease as the plain slide. 



The regulator or governor is driven by gearing, thus avoiding 

 all danger of breakage or slipping of belts, and the consequent 

 damage to the engine and machinery from the " running away " of 

 the engine. 



In addition to the steam jacket for preserving the temperature 

 of the cylinder, a covering of felt is employed around all the 

 exposed parts, and this in turn is covered by a casting of pc^lished 

 metal. The latter is the best possible protection against loss by 

 radiation. 



Fig. 1 represents a horizontal section of the cylinder and valves, 

 showing the peculiarities of the ciit-oft' motion. A is the C3-Iinder, 

 which is steam-jacketed, as are also the heads. B is a portion of 

 the bed piece, which forms also the front head of the cylinder, C 

 is the piston and C ' the piston rod, D is the main valve, and c e' 

 the induction ports, and F is the exhaust port. The body of the 

 valve is hollow, and conveys the exhaust steam from either end of 

 the cylinder alternately to the exhaust port F, whence it goes mto 



