CONDUITS, PORTAGE, ETC. 283 



loop, 7i, through which is passed a stirrer- bar, m w, made to sweep back 

 and forth in the lower side of the barrel, thus to agitate and mix the 

 substances considerably during the operation of the pump, every stioke 

 of the handle causing one or two strokes of the stirrer. 



The method of inserting and extricating the stirrer-bar is as follows: 

 It is raised with the pump until the end, w, comes opposite the bung- 

 hole. X, through which the bar may be pulled out by the cord, w^ which 

 is attached to the end, n, and also preferably to the bungs, r and 0, as 

 shown. Through the same hole the bar may be inserted. This stirring- 

 device is the simplest in construction and operation of any yet contrived, 

 while working as it does with reference to the concavity of the barrel 

 it is perfectly effective. 



Pumps having other external or internal constructions than those 

 shown here maybe similarly mounted, and it matters little if the eye or 

 the trunnion be either on the pump or on the slot-piece. But some of 

 the points in the internal construction of the pump may be briefly noticed 

 here. The lower extremity of the pistou-tube is closed and has a cir- 

 cular seat, above which is a slot-shaped entrance to the cavity of the 

 pistou-tube. Higher is another circular seat, and immediately above it 

 another inlet to the piston-tube. Between the two seats is a circular 

 slide-valve, which, bears a packing on its face and plays loose or free 

 up and down as caused by the pressure to open the lower inlet during 

 the downward stroke and to close it on the upward stroke. The upper 

 cap of the cylinder is quite loose about the i)iston-i)ipe, and holds one 

 end of a sheath or tubular packing, the lower free end of which fits 

 snugly around the piston-pipe and tighter to the same when the fluid- 

 pressure is on the outside of it. The piston-tube has about half the 

 cajjacity of the outer cylinder, and the whole arrangement is such that 

 the pump discharges during both strokes, being a constant-acting or 

 double-acting force-pump, which operates the same whether the dis- 

 charge be taken from a spout upon the side of the cylinder or from 

 the side or end of the jjiston-tube. With the discharge from the piston 

 end, and a suction-hose upon its opposite extremity, the pump may be 

 used apart from the barrel, like the so-called '^ fountain pumps " and 

 "hydronettes " of the trade. Its valves are all metallic, and it may be 

 made for the highest pressures or to throw any volume desired. 



This agitator-pump combination was devised for use with suitable ap- 

 paratuses of all kinds, but in the form here presented it is especiallj^ 

 designed for wheeled reser voirs. It works combined with a single de- 

 livery-tube or extension pipe with or without branches or nozzles of any 

 sort i)referred. This device embodies the simplest suitable stirrer and 

 double-acting pump for insecticide machines, is perfectly effective, and 

 I have found it the most satisfactory of all tested for squirting. 



Conduits^ Frames^ Portage, and Combinations of Appurtenances , without 

 regard for distinctive pump-characteristics, will receive more special 

 consideration in the descriptions of the following devices, which are 



