44 BULLETIN NO. 3, DIVISION OF ENTOMOLOGY. 
With the fine strainer on the suction end of the pump, clogging mate- 
rials in the water are prevented from entering the pipe system or the 
nozzles. Additional smaller gauze strainers were attached to the ends 
of the metal tubes in one set of pipes. They keep out dirt, ete., when 
the pipes are separated, but may not prove of importance. The proper 
method is to have a completely closed system, with folding joints that 
never need to be separated, so the whole can be folded into a small com- 
pact package for transportation by rail or to the field. Such a system 
has given great satisfaction by its convenience, as well as by allowing no 
obstacles to enter the nozzles. In spite of the most perfect precautions 
clogging will occur at the outset or before high pressure is attained, 
chiefly from the scales of iron separating from the interior of the pipe 
as loosened by rusting and jarring. With the finest nozzles (one sixty- 
fourth inch discharge) these seem to cause no more difficulty than with 
a Standard beveled one-sixteenth inch discharge. The nozzle faces may 
be removed to let out any obstacles which with low pressure are apt 
to clog the outlet and stop the internal rotation. But a high pressure 
Should always be used, and when this is once up the outlet may be 
pricked with a pin, and it will discharge with an almost explosive force, 
instantly starting an inconceivably rapid internal rotation, which, while 
sustained with due pressure, will by its centrifugal action prevent any 
particle from again finding the center of rotation from which the dis- 
charge takes place. This is especially true of the smallest nozzles; 
having an outlet just large enough to admit the insertion of a pin. As 
previously set forth, the inner edge of the outlet should generally be 
square or sharp. In the eddy chamber a great hydraulic pressure is 
generated, so great that by thumb pressure the discharge cannot be 
stopped. The power therein accumulated under high pressure is suffi- 
cient to cut through and disintegrate any obstructing particles or frag- 
ments, except those of the hardest kind, which are so heavy as to fly off 
from the center by their weight and momentum when the velocity 
of rotation is once up or quickly starts. 
The top adjustments of the descending pipes are very important. 
These tops may be variously hung, combined, or constructed. A knowl- 
edge of the irregularities of ordinary cotton fields, such as appear chiefly 
in crooks of the rows and in variations of width between them, prevents 
the idea of a stiff, unadjustable attachment of the tops of the pipes, 
which must travel between and more or less against the rows. Con- 
formity to all inequalities of the ground, its numerous ups and downs, its 
dead furrows, ditches, stones, and stumps, should likewise be attained. 
It must also be evident that a large, stiff apparatus is difficult to haul 
about, as it cannot be taken entire through gates except with much la- 
bor. Of course it is possible to disjoint the parts beforehand, and then 
serew them together tight afterwards when the field is reached. This, 
however, is hardly practicable. In fact the separating and joining of 
stiff metal joints by field hands isa failure. Plumber’s tools are neces- 
