186 OHIO EXPERIMENT STATION: BULLETIN 332 



careful study of the different types, by intending purchasers, in 

 ©rder that a machine adapted to their needs might be selected. 



The spraying machines of the present day may conveniently 

 be divided into two classes — the so-called mist, or fog, sprayers and 

 the solid-stream sprayers. 



SPRAYING MACHINES OF THE MIST, OE FOG, CLASS 



As the name implies, mist sprayers are so constructed and 

 equipped that the spraying material is delivered in the form of a 

 mist, or fog. The height of efficiency is the delivery of the liquid 

 broken up in the finest particles possible, in the most uniform man- 

 ner and in quantities commensurate with the demands at hand. 

 The field of usefulness of this type of sprayer for a number of 

 reasons is more general than is that of the solid-stream sprayers. 

 The more important of these reasons is that in general spraying 

 operations the plants to be sprayed are not extremely high and 

 under such conditions it is much easier to apply the foglike spray 

 evenly and economically. Issuing as it does in the form of a mist, 

 or fog, it settles on the object under treatment and remains in posi- 

 tion. In the spraying of high trees, however, this feature becomes 

 a serious handicap since the mist spray carries but short distances 

 and in order to cover the higher parts of the tree, ladders and climb- 

 ing must be resorted to. This process becomes a serious handicap 

 in a number of ways. It makes the work exceedingly slow and 

 tedious and by so doing adds greatly to the expense. Moreover, it 

 is difficult for the nozzleman to spray the tree perfectly when 

 clambering through the top. On account of the mechanics involved, 

 a spray of the mist, or fog, type is much easier produced than the 

 solid stream type, the latter requiring from 150 to 200 pounds addi- 

 tional pressure in order to work most satisfactorily. 



The principles involved in the construction and the essentials 

 to be borne in mind in the equipment of the mist sprayers are so 

 completely discussed in two previous publications from this Station 

 (1 and 2)* that these phases will be dealt with but briefly at pres- 

 ent, and the remarks to be made will be largely of a supplementary 

 nature in order to discuss a few points which apply particularly to 

 the selection and equipment of machines for use in shade-tree 

 spraying. Intending purchasers of spraying machinery who are 

 not well versed in the mechanics involved as well as in the status 

 of development of the modern spraying machine should not attempt 

 to make their selections without consulting these two publications. 



*These numbers and those which follow refer to the list of references, the beginning of 

 which will be found on page 473. 



