40 FIFTH REPORT OF THE ENTOMOLOGICAL COMMISSION. 
The same end maybe more easily attained, perhaps, by using, in con- 
nection with a good barrel or tank 
force pump, long hose with suitable 
supports, so that the spray may be 
brought to bear on the upper pur 
tion of the tree. Devices for this 
purpose will be described later on. 
Several forms of pumps are be- 
ing manufactured in this country 
with which satisfactory work may 
be done, and in the list of manu- 
facturers of insecticide apparatus 
appended to this article are given 
a number of addresses of reliable 
firms whose pumps I have used 
and can recommend. 
1 will content myself here with 
describing somewhat fully a force- 
pump which, in the work of the 
United States Entomological Com- 
mission and of the Division of En- 
tomology, has proved itself well 
adapted to the purposes desired. 
The double Cylinder brass Pump. — 
The special recommendation of this 
pump is the more freely given from 
the fact that at present no one holds 
a patent on it and various modifi- 
cations embracing the essential fea- 
tures are largely manufactured in 
different parts of the country. At- 
tention was directed to the advan- 
tages of this pump in the work of 
the commission, and it is illustrated 
in section and also in operation 
at plate XLVI of the fourth re- 
port. The pump, fitted in a barrel 
with stirrer attachment, there illus- 
trated, was specially constructed by 
Dr. Barnard, and has been several 
times mentioned and illustrated in 
Fig. 7.-Double cylinder brass pump. other official reports. 
The appended illustration (Fig. 7) is a sectional view of a similar pump 
now in use by the Division. 
The essential features of this pump are an outer cylinder a and an 
inner cylinder a\ which may be called the piston cylinder. This inner 
cylinder is provided with a valve, />, similar to the valve iut he outer cyl- 
