194 OHIO EXPERIMENT STATION: BULLETIN 332 



and teamsters for moving the horse-drawn sprayers of a city de- 

 partment, unless, of course, the department owns its own teams. 

 Moreover, any team is considered slow in this day of rapid transit 

 and the ones hired by the day are many times unreliable. Many 

 times the writer has seen a spray rig and gang idle for half a day, 

 or even a day at a time, simply because the driver failed to appear 

 with his team. The loss of a single working day during the limited 

 spraying season is a serious matter. At the present rate of growth 

 in the usage of power vehicles, this already difficult situation is 

 certain to become worse ; hence the self-propelled sprayer is certain 

 to come into general usage in the future. 



The chassis of almost any one of the trucks of the medium 

 heavy-duty type is well adapted to this purpose, and the power for 

 driving the spray pump may be taken directly from the motor, thus 

 doing away with the necessity of a separate engine for the sprayer 

 proper. At times other than during the spraying season, the 

 mechanism between the pump and engine may be disconnected and 

 the spray pump and tank removed, thus leaving the truck free for 

 general use. Thus, not only is less storage space required, but the 

 amount of machinery lying idle during the time when spraying is 

 not being done, is greatly decreased. 



One machine of the type described is already upon the market 

 and, is illustrated in Plate IX, Fig. 2. This one, however, is con- 

 structed for particularly heavy duty, and it is the writer's opinion 

 that a lighter machine could be built which would be more perfectly 

 suited to existing Ohio conditions. 



SELECTING THE MACHINE TO PIT THE NEEDS 



As a final word concerning the subject of spraying machinery 

 the writer wishes to emphasize again the value of study and dis- 

 crimination in selecting the machine that is best suited to do the 

 work required. 



Before any single line of sprayers is adopted for the use of a 

 city department they should be subjected to a very thorough exam- 

 ination by a mechanic well trained in the subject of spraying 

 machinery, in order to avoid imperfections in mechanical construc- 

 tion, and in addition a representative machine should be given a 

 thorough field test. This testing may involve the comparison of 

 different makes under field conditions; indeed, it is often possible 

 to induce the different companies to enter their machines into com- 

 petitive tests. 



After a given make and type of machine is decided to be 

 superior to the others, it is then the best policy to install all the 



