212 EEPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



age those in Plate XXV, Figs. 1, 2, 3, 5, and 6, are preferable. Descrip- 

 tions of these appear in the text below. 



When the extension piece or nose-piece of a spray-pipe is removed, 

 a broad spray of better quality is produced. This I regard as positive 

 evidence that in centrifugal nozzles a long discharge passage retards 

 the rotation and deflects the parts of the current more nearly toward 

 parallelism with each other and with the main axis of the passage, 

 thereby loosing the centrifugal or spraying power and producing a nar- 

 rower, poorer spray. By far the most perfect spraying effects are ob- 

 tained by the Eddy-chamber with an immediate axial discharge from 

 its face. There is no better established principle in mechanics than 

 that for dispersing purposes the immediate discharge from the wall of 

 a chamber is far superior to a pipe or barrel discharge. 



Eddy CHAivrBERED. — Eddy chamber jets are produced by new spray- 

 ing devices invented and developed in the progress of the commission 

 work. They possess a chamber usually of disk-like or annular shaj^e. 

 There is preferably for our present purposes a single inlet which dis- 

 charges into the chamber in an eccentric direction parallel to a tangent 

 to its circumference. Such a device gives to the fluid forced into it a 

 centripetal geometrically involute course, very completely converting 

 the in-current projectile or translatory velocity or motion into velocity of 

 rotation apparently increasing toward the center, which generally has 

 an immediate discharge by an outlet through the face of the chamber and 

 not by a long pipe. The fluid within proceeds in an inwinding course 

 approximating parallelism to the thin lips of the outlet, so that the tend- 

 ency to preserve this direction by its momentum after being freed dis- 

 perses it in the form of a whorl of diverging tangents from the lip 

 margins, as roughly indicated in Plate XXIV, Eig. 1. The principle of 

 in wrapping centripetal deflection with little or no axial movement until 

 the outlet discharge is reached is one of the special characteristics of 

 the Eddy jets. Thereby is gained an intense rotation at the discharge, 

 and a broad, fine spray therefrom. 



The velocity of rotation produced in these nozzles is remarkably rapid, 

 as exhibited by experimenting with one having a glass-faced chamber 

 to show the action within. 



The single round excurrent orifice is the largest possible for the quan- 

 tity of fluid thrown, and hence is less liable to choke; yet it is still bet- 

 ter in the Eddy jets proper from the fact that the intense rotation does 

 not permit a solid flow of fluid from the outlet, but only a hollow jet is 

 emitted, which allows the hole to be larger than the body of fluid pass- 

 ing through it. If the face has much thickness the outlet hole through 

 it should have its margins beveled on one or both sides to give a broader 

 spray ; also if it expand gradually, like the flare of a bugle, adhesion to 

 the. thin film of water i)assing out against its circumference spreads the 

 liquid much wider. And again, if the bevel or flare is such that the out- 

 let is narrowest at its inner commencement, or if this edge project some- 



