SLOT-NOZZLES. 197 



and any reduction of the discliarge capacity should be made by short- 

 ening the lips rather than by narrowing their interspace or slot. Dimin- 

 ishing by this rule the smallest slot attainable becomes ouly as loug as 

 it is wide, and loses the slot character. 



If coarse slots do not make the spray fine enough, the latter may be 

 thinned by adding a very short deflector lip, for it will be seen further 

 OD that the principles of deflection and rotation may be advantageously 

 superadded upon or combined with the slot in almost all cases. 



If the many-punctured principle is the worst for small jets, the slot 

 principle cannot rank much better for this purpose. We have seen that 

 to get a spray of very limited size the slot must be made either so nar- 

 row as to clog too much or must be shortened until it is about as long 

 as wide, or the spray is not thrown thin and broad enough without add- 

 ing a deflector. This suggests the substitution of the deflector in jjlace 

 of the slot. The round-hole deflector certainly ranks higher than the 

 slot-nozzle for small jets, but it in turn is superseded for this purpose 

 by the eddy-jets, as we shall see further on. 



The slot answers for heavy broadcast sprinkling j but also in this 

 work, if it has aperture enough not to clog, the spray will be too coarse 

 for administering poison homogeneously, and if narrow enough to give 

 sufficient fineness it will choke too much. Yet by certain improvements 

 these defects may to some extent be remedied. The slots may be cut 

 in various combinations, and several slotted rose-heads have been pat- 

 ented. A number of straight slots may be arranged as parallels, or as 

 whorls of radials, or diagonals 5 also, curved slots maybe grouped con- 

 centrically, or as whorls of radials, or diagonal curves or spirals. The 

 only object in multiplying the number of slots in one and the same noz- 

 zle is to increase the volume to make large sprays without diminishing 

 the quality by making a smaller number of slots coarser 5 for the finer 

 the slot the finer the spray and the less its volume. Where force is ap- 

 plied groups of slots are preferable to the groups of smaller perforations 

 of the many-punctured nozzles of the preceding group, and when rota- 

 tion of the liquid is introduced in many-slotted chambers the cuts should 

 be preferably concentric and thus parallel with the rotary current. 

 • The slits may be cut on ends or sides of pipes, heads or nose-pieces 

 of all forms, each end-form like each slot-pattern having its own pecu- 

 liar adaptation ; but the slotted surface should generally be in some 

 way curved with cylindrical, conical, or spfieroid contour to emit the 

 spray in a radiating manner, and thus spread it more widely, or collid- 

 ing slot-jets can be used. A rounded end should preferably have an 

 internal cavity of capacity and form suited to adapt it for a rotation- 

 chamber, since the rotary principle may also be introduced as an im- 

 provement in nozzles of this group. 



Selecting with reference to these principles, a,nd also for the purpose 

 of adopting a nozzle- end of such form that it can be cut with slots of 

 any form or grouping that may be made on either sides or ends, and 



