40 FIFTH EEPORT 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 por 

 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. 



I 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- 



J ^ trated, was specially constructed by 



II Dr. Barnard, and has been several 



— ll 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, b, similar to the valve int he outer cyl- 



