THE MONTHLY BULLETIX. 61) 



generation and the suggestion to fumigate at night constituted two most 

 important steps in the development of the system and still survive as 

 essential parts of the present most approved practice. 



APPEARANCE OF THE FUMIGATING MACHINES. 



The abandonment of the outside generators during the early experi- 

 ments was due no doubt to the impure cj^anide that was first used. It is 

 thought that if the experiments had been conducted with the high grade 

 of materials that are now available at a reasonal)le price, this mode of 

 generation would have been perfected and the pots would never have 

 appeared. The pure materials now universally used have made pos- 

 sible the development of a machine which promises to be one of the 

 greatest advances that has recently been made in the art of fumigation. 



The attention of the speaker was first called to the Owl fumigating 

 machine during the summer of 1913 by Mr. William Wood, County 

 Horticultural Commissioner of Los Angeles County, who made the 

 statement at that time that some 2,000 trees had been fumigated on 

 the county farm with very satisfactory results. The acquaintance of 

 the inventor, Mr. William Dingle, was made at that time and the 

 machine was photographed for the first time (Fig. 15). In sending 

 Mr. Dingle a copy of the photo of the machine, the following comment 

 was made: "Unless some unforeseen diflficulty arises, it seems to 

 [)romise to be one of the greatest advances in the art of fumigation 

 which has been recently made." The speaker was vfry much i)n- 

 |)i"essed with the possibilities of the machine and has followed its 

 progress as closely as circumstances would permit from that time on. 



During the season of 1913, eight machines were constructed and leased 

 in the Covina fumigating districts and did admirable work during 

 their short lives. Their construction was unable to withstand the 

 terrible corrosive action of the chemicals at the high temperatiires 

 produced by the action of the sulfuric acid upon the solution of 

 cyanide which was used. 



In the interval between that season and the present, the machine 

 was perfected in various waj's and there are at present some twenty 

 machines in operation. 



DESCRIPTION OF THE OWL FUMIGATING MACHINE. 

 The construction of the machine is rather simple. It consists of a 

 generating cylinder of about thirty or forty gallons capacity mounted 

 on two wheels and provided with shafts, and may be moved about the 

 field by one horse. Mounted directly over this main cylinder are two 

 small supply tanks in one of which is contained the concentrated 

 solution of cyanide. In the other is contained concentrated sulfuric 

 acid. Each one of these supply tanks is connected by means of a 

 three-way valve to a measuring cylinder or graduate. The valves are 

 each operated by a lever and by adjusting the position of this lever, the 

 solution flows from the supply tank into the graduate. A slight change 

 in position stops the flow of liquid. By setting the lever in a third 

 position, the liquid will flow from the graduate into the main generating 

 cylinder. In practice, the proper amount of cyanide solution is meas- 



