REMEDIES AGAINST FOREST INSECTS. 



41 



inder 6^ and above the valve b the iauer cylinder is closed as shown in 

 the cut. Thus it represents a displacement cylinder and its capacity 

 bears such a relation to the outer cylinder that on the downward stroke 

 it displaces a body of water equal to that taken up by the upward 

 stroke of the piston, thus producing a constant pressure in. a simple 

 single-barreled pump. 



The packing d is held in place by a metal follower and fits snugly to 

 the inner surface of the outer cylinder. The pipe, c, is of rubber hose and 

 made of any length desired to suit the depth of cask or tank and with 

 a fine wire strainer on the bottom. The head of the pump is of cast iron 

 and bulged to allow room for a considerable head of water ; iron flanges 

 extend out from its lower part and furnish support by which if is bolted 

 to the tank. All of the working parts are brass. The packing burr and 

 follower around the upper end of the piston cylinder are the same style 

 as ordinarily used with steam machinery so as to withstand any reason- 

 able pressure. The head to which is attached the compensating bar 

 screws into the top of the piston cylinder. The outlet is tapped through 

 the bulged cast-iron head, and the pressure is much better if a good- 

 sized air chamber is attached to the discharge pipe just outside of the 

 pump head. 



The pump from which Fig. 7 was made has two discharge pipes, and 

 one man easily supplies pressure for two ordinary streams of spray. 



Fig. 8.— Sin{;le-discharge pump. 



Fig. 8 shows a similar pump entire, fitted with a single discharge pipe. 



