ETC. 113 



pipe extension rods. etc. Altogether many hundred individual tests 



were made, and the total result of the work tended to show that 

 none of the pumps could be relied upon to give uniformly the 

 percentage of oil desired. A detailed discussion of the mechanical 

 faults of these pumps is not necessary at this time, hut it may In- 

 stated that those pumps made with hut a single pump drawing from 

 the barrel and oil tank at once were found entirely unreliable, whereas 

 those having two pumps, one in the oil and one in the water tank, 

 and the percentage of oil regulated by the length of the stroke of the 

 pumps, were found much more reliable, although in many cases they 

 failed to deliver the proper percentages at the pump before the liquids 

 mixed. In none of this type, even with the double-extension rod 

 having an inner tube conveying the oil to the nozzle, was the unequal 

 mixing of the oil and water in the hose and extension rod wholly 

 prevented, so that variable percentages frequently occurred. The 

 results of this work were never published, but the records exist in 

 support of the above summary. 



It soon became apparent that to eliminate the mixing of the oil 

 and water in the hose and pipe before reaching the nozzle, some form 

 of nozzle must be devised which would mix the two liquids as they 

 left it. Such a nozzle was therefore devised and a working model 

 was made by Queen & Co., a drawing of which was made by them 

 as shown in fig. 6. In the Thirteenth Report of the Delaware Agri- 

 cultural Experiment Station (1901. p. 196) the writer made mention 

 of this nozzle as follows: ''We have had a nozzle made according 

 to plans originated by us which it is trusted will prove more snti>- 

 factory in making a uniform mixture of a given percentage of oil 

 and water." 



In his recent bulletin upon the San Jose scale." Mr. C. L. Marlatt 

 remarks concerning the oil and water mixture, as follows : 



The best outlook for good apparatus of liiis sort seems to bo in carrying tbe 

 oil and water in separate lines of hose to the nozzle, uniting them in the latter. 

 and in maintaining an absolute equality of pressure on both oil and water 

 tanks by employing compressed air as the motive force, kepi up by an air pump, 

 the air chamber communicating with both of the liquid receptacles. * * * 

 One or more manufacturers are now working on an apparatus o\' this 

 description. 



This so closely describes the system originated by the writer in 

 1901 that it seemed wise to make a record of our work along this 

 line in the proceedings of this association, as the writer was not 

 aware that any manufacturers had taken up the idea or indeed that 

 it had attracted any attention, though we had described the appa- 

 ratus to several entomologists in a general way. 



<* Bulletin 62, Bureau of Entomology, U. s. Dept ol Agriculture, p. 77. 



7487— Xo. U7— 07 8 



