498 PROCEEDINGS OF THE THIRD ENTOMOLOGICAL MEETING 



A fan situated near the feed-in causes a continuous draft of air to 

 circulate through the machine. The air is exhausted from the hot 

 air generator, a brick chamber surrounding the furnace. 



The temperature is regulated by a damper which opens or closes 

 by means of screw. This damper is interposed between the hot air 

 generator and the hot air chamber. A thermometer passing into the 

 body of the hot air chamber indicates the heat of the air at that part 

 of the machine, and is used in regulating the temperatures. By opening 

 the damper as soon as any indication of a fall is evident, and by closing 

 it as soon as a rise commences, it is easily possible to keep the machine 

 regulated to plus or minus half a degree of the desired temperature. 

 This regulation could, of course, be made automatic if necessary. We 

 did not fit an automatic control on account of the extra expense. 



In working the machine the following factors have to be 

 considered : — 



(1) The outside temperature=the temperature of the seed. 



(2) The time required to pass through the machine. 



(3) The temperature the machine is regulated to give. 



(4) The temperature of the seed at the exit. 



Of these four factors the last is the most important, and the other 

 three factors must be regulated so as to keep the temperature of the 

 seed at the exit between 48° C. and 55° C. The best temperature to 

 regulate for is 50°C. 



When working the machine, the time required for the seed to pass 

 through is not interfered with : the temperature required in practice 

 is adually obtained by observation of the thermometer situated near 

 the regulating damper, these readings being supplemented and corrected 

 by observations of the temperature of the seed at the exit. 



The temperature regulated for is not so important as the tempera- 

 ture of the seed at exit. 



This machine, which was quite successful in killing all the worms 

 in the seed without injuring germination, was used for the treatment 

 of several hundred ardebs of seed, much of which was intended for 

 exportation. Much of the work done with it was of great importance, 

 in that it famiharized us with the problems of seed treatment by heat 

 before the introduction of other, more perfect machines ; and also 

 that the results obtained in the growing of treated seed enabled us to 

 counter many, one might almost say frivolous, objections which were 

 urged by interested parties when opposing legislation compelUng seed- 

 treatment in the gimieries. 



