11 March, 1918.] 



T"//( eyard ^p railing. 



143 



Evolution of the Modern Spray. 



Tlie efficacy of copper was discovered as far back as 1885. At this 

 time modern spray pumps were unknown, and the first applications of 

 Bordeaux mixture were made by means of a brush or whisk of heather 

 twigs tied together. The sprinkling thus carried out was manifestly 

 inferior to the fine modern spray; nevertheless, a remarkable degree of 

 protection was obtained. Improvements were attempted, and numerous 

 mechanical devices were introduced, among the earliest of which were 

 rotary brushes, such as are shown in Figs. 1 and 2 ; these were so devised 

 that the bristles could be momentarily held back by a transverse bar. On 

 their sudden release, the liquid with which they are wetted is projected 

 on to the vine in small drops. Improvements were gradually introduced 

 until the spray pump, in something like its present form, was evolved, 

 one of the most noteworthy developments being the introduction of the 



Fig. 



-Riley's Cyclone 

 (after Viala). 



Nozzle 



Fig. 4. — ^Raveneau ' s . jet (after Viala) . 



Riley or cyclone nozzle,* which really constituted a revolution in spray- 

 ing, and is at the present day, in one or other of its improved forms, the 

 one most generally used. Fig. 3 shows the earlier form of Riley nozzle. 



* The earliest description of the fvclone Kozzle, and the principle on which it is based, seems to be that 

 which is contained in the fonrth or final report of tlie I'.S.A. Entomological Commission on the Cotton 

 Worm, by Chas. V. Rilev, P.H.I)., published in 1881. A chapter contributed by Professor W. S. Barnard 

 deals with the different" nozzles in use, and among these several tjT)es of centrifugal or eddy-chamber 

 nozzles are described. . . ^. . . , i.,. ^ , 



That we are indebted to Professor Eiley and his staff for this ingenious invention is shown by the fol- 

 lowing extract from this report :— " Eddy chamber jets are produced by new spray devices invented 

 and developed in the progress of the commission worlf." , , ^ , ...... x 



The following particulars, extracted from the same report, will no doubt be read with interest : — 



" Centrifugal sprinklers expand the jet by giving it a rapid rotary motion, which, by the centrifugal 

 force generated, throws the fluid into a shower of particles. .,.,..,... j. , 



The chamber is usually of disc-like or annular shape. There is preferably a single inlet which discharges 

 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 

 towards the centre which generallv has an immediate discharge by an outlet through the face of the chamber, 

 and not bv a long pipe. The fluid within proceeds in an in-\vinding course approximating parallelism 

 to the thin lips of the outlet, so that the tendency to preserve this direction, by its momentum, after being 

 freed, disperses it in the form of a whorl of diverging tangents from the lip margins . . • . • • • 

 The principle of in-wrapping centripetal deflection with little or no axial movementuntil 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 action, 

 within." 



