248 REPORT 4, UNITED STATES ENTOMOLOGICAL COMMISSION. 



while others emit the spray in the direction of the axis of the pipe. The 

 pipe, ij should be prel'erably so extended as to carry its jet, s, beneath the 

 plants. The pipe, ?, may be inserted in the wall of the can at any point 

 above the desired level of the liquid which closes the lower end of the 

 pipe so that air cannot ascend to the large, tight reservoir. Hence, the 

 liquid can rise no higher than to close its lower orifice. As soon as the 

 liquid is lowered so much that air can enter and pass to the upper res- 

 ervoir liquid enough will descend to close the entrance again. With 

 this arrangement the feeding of the blast goes on, and^ the small can 

 does not have to be filled. This supply -tube may have a stopper, or be 

 connected with an automatic supply from a larger, higher reservoir, as 

 previously explained. It may be seen that whether the angle, x^ or the 

 side, a, or the side, 7i, be downward the passages at the corner, y, will 

 always be above the liquid, so that when the ini-trument is in Operation 

 it can be directed downward or u^jward, as well as horizontally. By 

 this machine the blast is fed with certainty and strongly. Since there 

 is no immediate communication of the surrounding atmosphere with 

 the reservoir, p, the liquid is not raised in the pipe, x-y, by the ordinary 

 process of atmospheric pressure, but the blast-pressure, which is more 

 powerful, is applied. Here it should be noticed that the blast also 

 bears down upon the liquid in the tube, x-y, as well as on that in the 

 chamber, and were its force equal in both these places the water would 

 not rise, for the elevation must be due to the reservoir pressure exceed- 

 ing that in the feed-tube. To secure this condition the main blast be- 

 tween the incurrent and excurrent orifices, at y, should be partially ob- 

 structed, and this can be accomplished in various ways, here by one 

 side of the tube, x-y, projecting into the main passage. It can also be 

 done by a crook, or by having the main passage made larger beyond the 

 pressure-hole. It should be noticed that with this device, even when no 

 valve is used between it and the bellows, the liquid will not flow back 

 into the bellows past the pressure-inlet, for there it naturally enters 

 again into the chamber. 



An important feature of this device depends on the fact that it may 

 be turned upside down, and so works with less effort, while gravitation 

 causes the liquid to feed into the blast uninterruptedly by way of what 

 was in the other case the distal ijressure-hole, and the tube, x-y, or a 

 hole preceding, it now serves to pass the blast-pressure above the 

 liquid. 



An apparatus having these characteristics, also adapted to poisoning 

 under-surfaces and others, is shown by a plan view in Plate XXXII, 

 Fig. 6. The bellows, v, has a very long blast-pipe, i, with an angular 

 discharging-nozzle, s, which can be turned on the pipe, i. At the base 

 of the pipe, ^, is a crook, recess, valve, or partial septum, to prevent the 

 poison from entering the bellows. The reservoir, p, has a supply en- 

 trance, ?, which may be closed, or can have a pipe connection as an 

 automatic supply from a higher reservoir, carried by the operator or a 



