42 BULLETIN NO. 3, DIVISION OF ENTOMOLOGY. 



The quantity of liquid and poison used also depends on the various con- 

 ditions stated as determining the rapidity. The amount of liquid to the 

 acre, as near as could be estimated under the circumstances, ranged 

 from 10 to' 40 gallons, according to the size of the spray-discharge and 

 ■of the cotton. The quantity of poison is in direct proportion thereto, 

 being one-eighth to one-half a pound of London purple, or one-fourth 

 to four-fourths of a pound of Paris green to the acre. 



The stirrer-pump device is a most perfect thing for the purpose and 

 gave the greatest satisfaction. This contrivance is described and illus- 

 trated in the annual report for 1881- , 82 (pi. ix, pp. 159-161). The pump 

 has heavy metallic valves, and its piston-head has no soft packing, so 

 there is nothing about it that can get out of order. Yarn packing is 

 used in the stuffing-box at its top. Being double acting it throws a 

 strong and constant stream. Only one trunnion-eye need be moved? 

 and a single iron wedge, instead of two, is sufficient for setting it. The 

 wedge has on its head a catch whereby it is easily pryed out, and an eye 

 by which it is chained fast to prevent losing it. In place of the wooden 

 stirrer bar formerly employed I have made an iron one having a spring 

 at the middle to clamp snugly in the eye at the bottom of the pump. 

 This will not weaken with age or break. The cord or chain for pulling 

 out the bar is not essential, as by having the end bung-hole of two 

 inches diameter a pair of tongs or pinchers can be inserted to take hold 

 of the end of the stirrer and extract it. The main hose or pipe has a 

 screw union, by which it is easily separable from the pump. 



The descending pipes between the rows should have flexion and tor- 

 sion in their joints or segments or hangings. The ground beneath 

 the cotton-rows is highly ridged, and the mid-furrow between each 

 pair of rows is deep. The ground thus formed operates upon the 

 lower parts of each descending pipe or its appurtenances, when suita- 

 bly shaped, so as automatically to guide the pipe and its nozzles 

 between the rows, and to follow any crooks therein even when the 

 conveyance is not driven in conformity with such irregularities. This 

 automatical adjusting is allowed to a large extent even when the 

 top of the descending pipe is firmly or non-adjustably attached, pro- 

 vided that the descending pipe be flexile in some part of its course. 

 This was shown in the earlier flexile forked machines which were 

 tested for this Department near the Atlanta exposition. For the ob- 

 ject in question the descending pipe may be flexile throughout, but it 

 is more commonly preferable to construct this pipe of stiff segments 

 having one or two flexile joints, or very short hose segments; one at 

 its top, and another at about two-thirds or one-half of the way down- 

 ward therefrom. It is also generally best to make these flexile seg- 

 ments or joints of three-ply or two-ply hose, and only of such length 

 as to allow them to bend like knee-joints, and to suffer a semi-rotation 

 or semi-torsion. This construction prevents the trailing-fork or other 

 <end part from getting turned upside down, or from remaining, in wrong 



