48 BULLETIN NO. 3, DIVISION OF ENTOMOLOGY. 



merit of results dependent thereon. The tests showed that with a pipe- 

 system, without lateral adjustability at the top, very few rows, usually 

 not more than four, can "be treated at once. In this small form the whole 

 pipe system can occasionally be moved laterally by hand as the row 

 irregularities require it. 



The forks were operated dragging upon the ground, and also set at 

 different heights. The ratchet for vertical adjustment subserved this 

 purpose satisfactorily. AVhere it is desired to spray the base and interior 

 of the plants from beneath, the nozzle arms must necessarily be car- 

 ried near or on the ground, and with medium to small cotton this method 

 also sprays the tops sufficiently well, but if the growth be heavy and 

 dense it proves better to set the forks higher for more thoroughly poi- 

 soning the tops. 



The stirrer pump worked admirably ; but a larger pump of the same 

 kind was necessary to treat a greater number of rows, to ascertain how 

 large a number it is possible or advisable to spray at a time. While the 

 large pump was being constructed and shipped the time limited by my 

 orders expired. 



Four rows may be set as the number it is most practical to treat at a 

 time with the kind of machine in question. 



The springs of the fork-arms should be larger and have a longer bend 

 than in the samples taken, since the unyielding attachment of the stem- 

 pipes to the stiff supporting pipe above throws on the springs much 

 greater strain than occurs in the machines having descending parts 

 hung to operate independently of each other. 



Until my time had expired worms were not abundant enough to study 

 the effects on them of the coarser and finer sprays applied, but the 

 coarser spray was more injurious to the foliage with poisons, and still 

 more so with petroleum. 



The standard form of eddy-chamber nozzle was used with discharges 

 of different sizes. The smallest discharge holes, of -Jj to T u of an inch 

 diameter, with very high pressure, gave the most satisfactory results. 



The u actual cost, and the actual area covered by a given amount of 

 liquid," vary greatly with the width between the rows, the sizes of the 

 sprays and of the plants, with the number of nozzles, with the amount 

 of pressure applied and the volume capacity of the pump, the velocity 

 at which the machine is drawn, etc. On account of the complexity of 

 the question, and especially because of leakage from imperfect pipe- 

 joints and for want of other and larger apparatus, the question could 

 not be solved with anv exactness. * 



