330 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



It will already have been gathered, from what has preceded, that the 

 chief insecticides are applicable in liquid, and as liquids have an ad- 

 vantage over powders in field use, instruments for atomizing and dis- 

 tributing liquids constitute the most important part of insecticide 

 machinery. The desiderata in a spray-nozzle are, ready regulation of 

 the volume to be thrown ; greatest atomizing power, with least tendency 

 to clou ; facility of cleansing or ready separation of its component 

 parts; cheapness; simplicity, and adjustability to any angle. 



I will content myself with exhibiting one which meets, perhaps, more 

 of these requirements than any other in use, and which works on a new 

 principle applicable to many other purposes than that for which it was 

 designed. It is what has been described and illustrated in my late 

 official reports as the eddy or cyclone nozzle, and consists of a small 

 circular chamber with two flat sides, one of them screwed on so as to 

 be readily removed. Its principal feature consists in the inlet through 

 which the liquid is forced being bored tangentially through its wall, so 

 as to cause a rapid whirling or centrifugal motion of the liquid which 

 issues in a funnel shaped spray through a central outlet in the adjust- 

 able cap. The breadth or height, fineness or coarseness of the spray, 

 depends on certain details in the proportions of the parts, and especially 

 of the central outlet. The nozzle originated at Selma, Ala., in the fall 

 of 1880, while I was in the field, with my assistants, working at con- 

 trivances for the destruction of the Cotton-worm. In a discussion as 

 to whether liquid forced tangentially into such a chamber would whirl 

 or not, Dr. W. S. Barnard took the affirmative position, and experiments 

 with a chamber improvised with two watch crystals, in which the 

 motion of the liquid could be observed, proved the correctness of the 

 theory. The final form of chamber adopted is the result of numberless 

 experiments carried on by Dr. Barnard in my work, both for the United 

 States Entomological Commission and the Department of Agriculture, 

 and the different phases of its development may be seen by the various 

 models which I have brought for your inspection. 



Ladies and gentlemen, I thank you for your attention. 



KEROSENE EMULSIONS. 



It is doubtful if in the history of economic entomology in this coun- 

 try so great an impetus has been given to the destruction of insects in- 

 jurious to vegetation as by the discovery of the simple methods of 

 emulsifying kerosene, which we first made public in 1880, and which 

 have been fully set forth in the reports and bulletins from this Bureau 

 since. It is useful against many plant-feeding insects which are not 

 affected by other insecticides, and since we announced its value against 

 underground insects, a year ago, its use has become still more gen- 

 eral. It is, however, against the scale-insects injurious to the Orange 

 that it has so far proved most satisfactory. We are, therefore, pleased 

 to state that Mr. Hubbard, special agent of the Bureau in Florida, re- 

 ports that success has everywhere followed its judicious use in all 

 parts of that State, and that the experience of another year warrants 

 what he has heretofore said in its behalf, and that it is destined to su- 

 persede all other insecticides for use in orange groves and nurseries. 



Nevertheless, former warnings against the use of mere mixtures or 

 imperfect emulsions of coal oil and milk or soap solutions need reitera- 



