148 THE GYPSY MOTH. 



zles are operated on the same principle and both have been 

 much used in the gypsy-moth work. A good climber us- 

 ing the Gem nozzle can spray large trees both thoroughly and 

 rapidly. 



When it is impossible to reach the ends of branches with 

 a fine spray, a turn of the nozzle will cause a heavier spray 

 to be thrown to a distance of ten or twelve feet. If neces- 

 sity requires, this can be reduced to a stream which can be 

 forced upward for thirty feet, where it will break into drops ; 

 but when the foliage can be reached with a spray, the use 

 of the stream should not be permitted, as such work does 

 not give the best results. 



There are some objections to the use of these nozzles. They 

 waste more or less of the liquid and do not distribute it so 

 finely as some other nozzles. They also may tempt the 

 workman to avoid climbing by substituting the stream for the 

 spray where the branches are not easily accessible, thus im- 

 pairing the efiiciency of the spraying. Yet if the operations 

 are superintended by competent men, this may be guarded 

 against and the work done far more rapidly than with non- 

 adjustable nozzles throwing a finer spray. 



The Lowell nozzle (Plate XXIV., Fig. 2) consists essen- 

 tially of two brass tubes placed one within the other. The 

 inner tube at its posterior end bears a coupling by means of 

 which it is connected with the hose, while the anterior end 

 terminates in a tapering point at the base of which on op- 

 posite sides are two openings which allow the fluid to escape 

 into the chamber between the tubes. The cone-shaped point 

 of the inner tube tapers for al:)Out two-thirds of its length, at 

 which point its diameter is abruptly enlarged and then tapers 

 again at an increased angle to its apex. On the outside of the 

 inner tube is a coarse screw thread which moves on a blunt 

 screw inserted through the side of the outer tube and by 

 this arrangement the latter is moved forward and backward. 

 This outer tube, which is slightly shorter than the inner one, 

 closes on the latter at the posterior end by means of a liand 

 of packing held in place by a movable nut. At its anterior 

 end it is widened to form a bell-shaped opening which at 

 the centre closes tightly around the tapering point of the 

 inner tube. When in use the outer tube is slid forward by 



