112 SOME SOl'TH INDIAN INSE< rS, BT< . ((HAP. XI. 



For the ordinary cultivator, .1 Knapsack Sprayer or Pressure Sprayer 

 u, page 113) will fulfil all ordinary requirements. It may be used 

 for spraying all ordinary crops and. with a suitable nozzle or 

 extension rod, for small trees up to twelve or fifteen feet high. 

 Various patterns are obtainable in India at a cost of about thirty- 

 five to fifty rupees each. 



Barrel Sprayers, so railed because they are usually mounted in a 

 barrel which acts as the tank tor the spray-material, are larger 

 pumps which are specially adapted for spraying on a moderately 

 large scale. The barrel usually holds about fifty gallons and is 

 mounted on a detachable frame supported on wheels so that it may 

 be transported easily, the whole apparatus when full weighing some 

 six hundred pounds; a larger tank is not practically useful under 

 ordinary conditions in India. The pump should supply at least 

 two nozzles at 80 to ioo pounds pressure with ordinary pumping, 



Pump in action. (Author's'original photo). 



and it should have a large air-chamber within the pump-barrel in 

 order to maintain a constant pressure. The air-chamber should 

 not projeel above the barrel, as such an arrangement makes the 

 pump top-heavy and exposed parts are especially liable to break- 

 age. For the same reason the handle and similar parts should be 

 made of malleable or galvanized iron and not ol cast iron. A good 

 mechanical agitator is an essential fitting and this should be of the 

 paddle type («., a metal frame or sheet attached to and working 

 with the pump). Some machines are fitted with agitators of the " jet " 

 type in which a current of air is driven into the spray-liquid from the 

 bottom of the pump-barrel ; this method is unsatisfactory in practice 

 as it allows a loss of pressure without sufficiently agitating the 

 liquid. The pump should be readily removable from the barrel 



