198 The Spraying of Plants. 



which would throw 7 a solid stream. It was constructed so that 

 the volume of liquid was gradually contracted as it approached 

 the outlet orifice, and the stream was not broken up until it had 

 been carried some distance from the nozzle. The stream was 

 often changed to a spray by screwing a rose, or some similar 

 device, to the end of the nozzle. The openings in these attach- 

 ments still allowed the passage of solid streams of liquid, but 

 these were so reduced in size that the fluid was broken up into 

 much smaller drops. 



Three principles have been utilized in the construction of all 

 spray nozzles now 7 in use. These principles form a basis for 

 the natural division of nozzles into three main groups, these 

 allowing of still further subdivision : 



1. Spray nozzles in which the stream is more or less broken 

 directly in consequence of the modifying action of the margins 

 of the outlet orifice. 



2. Spray nozzles in which the stream, having passed the 

 outlet orifice proper, is modified by obstructions which affect 

 its free and direct outward passage. 



'I. Spray nozzles in which a strong rotary motion is given 

 to the liquid, and in consequence of this motion, the stream 

 leaving the outlet orifice immediately assumes the form of a 

 spray. 



These principles are mentioned in the order in which they 

 probably came into use. Some of the later nozzles combine 

 the first two principles, and others seem to form a connection 

 between them, although one principle or the other strongly 

 predominates. Some of the nozzles belonging to the various 

 groups are here briefly considered. 1 



The first group was long represented by nozzles throwing a 

 solid stream, the outlet orifice being circular. A new type of 

 nozzles, a modification of these, began to be made about 1875. 

 This class became known as graduating spray nozzles, from the 

 fact that the character of the liquid thrown could be varied 

 from a solid stream to that of a fine spray, by introducing into 

 the outlet orifice a pointed piece of metal or lance. This entered 

 the orifice from the inner side, and the further it was intro- 

 duced, the smaller became the opening and the finer was the 



1 For a more complete description, with illustrations, of many of the nozzles 

 here mentioned, see American Gardening, 1893, May, 266. 



