CENTRIFUGAL NOZZLES. 213 



what sharply into the chamber as well as into the beginning of the out- 

 let passage, there will be less liability to clogging. 



While clogging seems reduced to a minimum in these nozzles, in view 

 of the fact that any nozzle may be filled with rubbish, a removable face, 

 cap, or plug in combination with the rotation chamber is used for those 

 of the small size, but the necessity for cleaning need not occur if proper 

 attention is given to straining with devices such as are described else- 

 where in this report. 



The advantage of using only a single entrance to a nozzle is easily 

 seen. One large orifice for the given volume of water to be thrown is 

 less likely to choke than two, each of half its capacity. On this account, 

 and in order not to increase friction, more than one inlet should not or- 

 dinarily be used. But, on the contrary, most of the rotation nozzles that 

 have been put upon the market have at least two inlets, and suffer from 

 clogging more than twice as much as they otherwise would. To avoid 

 the same impediments it is also desirable to have the inlet or inlets as 

 straight as possible and eccentrically parallel to a tangent to the out- 

 side of the rotation cavity; yet, a curve is not specially objectionable 

 in this passage if it be in the direction of rotation, as shown in Plate 

 XX Vi, Fig. 4, for it then may serve rather as an auxiliary thereto. 

 The best form of inlet is the straight, tangentially inserted tube or pas- 

 sage in the circumference of the rotation cavity, and this appears in 

 most of these new rotation nozzles, as in Plates XXIY and XXY. But, 

 on the contrary, every ceutrifugal nozzle that I have been able to find 

 in the trade depends on some objectionable form of entrance *passagej 

 retarding the motion, liable to choke, or with passages with difficulty 

 accessible for cleaning out. It should be remembered that a crook equiv- 

 alent to a right angle, by its resistance, causes over one-third more la- 

 bor at the force-pump as wasted energy, or, inversely, with the same 

 power at the pump not two-thirds as much spraying power at the noz- 

 zle will result. 



An entrance-tube at an angle with the axis of the chamber, but tan- 

 gential to the outside, gives an advantage by adapting the spray for 

 sprinkling from beneath upwards or from above downwards, while it 

 serves well for broadcast throwing also ; and it should be observed that 

 in these nozzles which at present seem most preferable for poisoning 

 cotton from beneath, the tangential entrance-tube stands about at right 

 angles to the axis of the spray. At the same time, the nozzle does not 

 project upwards to any marked extent above its feed-pipe, and hence 

 cannot catch upon the plants under or against which it is drawn. On 

 the other hand, the long barrel-nozzles cannot be used for this purpose, 

 because they form a hook or angular projection, which would hang upon 

 the plants. 



Certain variations of these characteristics already given will be pre. 

 sented in the examples to be described further on, which show the con- 



