SOLID-STREAM SPRAYING IN NEW ENGLAND. 3 



efficiency. Our efforts led to the construction of a high-power solid- 

 stream machine, which was an improvement over those used in the 

 previous season. These machines were assembled from stock parts 

 purchased in the open market and consisted of stationary engine, 

 with battery ignition and single cylinder or duplex pump. 



While the results accomplished were an improvement, they were 

 not satisfactory as the pump did not furnish a steady pressure and 

 the engine caused too much vibration. In 1907 a two-cvlinder 

 marine engine and triplex cast-iron pump were used. This machine 

 was an improvement over the first, but the pump would not stand 

 high pressure and its use resulted in a large amount of valve trouble. 

 Later a four-cylinder marine engine was used with high-tension 

 magneto and a triplex pump made of phosphor-bronze having metal 

 valves. This proved satisfactory, and practically the same outfit is 

 in use to-day. 



DESCRIPTION OF APPARATUS. 



The high-power solid-stream sprayers being used by the Bureau of 

 Entomology are assembled as follows (PI. Ill) : 



Caravan running-gear, U-shaped tank, phosphor-bronze pump, 14- 

 horsepower marine engine. Eunning gear built of best oak stock 

 with high-grade iron. Wide tires on wheels, cut-under front wheels, 

 with springs all around, fitted for a two-horse hitch. Tank made 

 from select pine stock, capacity of at least 400 gallons, with a solid 

 roof capable of carrying supplies on the top. An arch made of heavy 

 steel straps is bolted on the inside to protect the agitator. This ar- 

 rangement provides space in the tank for storing the hose while the 

 sprayer is being moved from place to place and eliminates the need 

 of a supply wagon, reducing the cost of operation about $5 a day. 

 The roof extends over the engine, and side curtains are used to protect 

 it from weather. Pump, triplex type, with cylinders, valves, valve 

 chambers, and plungers made of a high-grade phosphor-bronze with 

 a tensile strength of 35,000 pounds per square inch. This makes a 

 much lighter and more compact pump than would be safe if cast iron 

 was used, as the latter rarely has a tensile strength of more than 

 15,000 pounds per square inch. The cylinders and displacement 

 chambers are cylindrical in design, so as to offer no flat surfaces to 

 pressures ; thus greater strength can be secured with the same amount 

 of metal. The valves and waterways are extra large to permit high 

 speed while filling. The valve chambers are so designed that any 

 one valve may be removed without disturbing another. The uprights 

 are made of high grade iron with babbitted bearings. The crank is 

 a drop-forging which usually has an elastic limit of over 74,000 

 pounds per square inch and is not subject to crystallization. Cast- 

 .iron cranks should be avoided, as they usually have an elastic limit 



