17 - 



If all these factors art 1 constant, the temperature of the treated 

 seed will also be constant. To take them in turn, the initial tem- 

 perature of the seed will vary considerably in the course of a whole 

 ginning season. During any one day, however, the variation will 

 be so small as to be quite negligible. The rate at which the seed 

 enters the machine should prove fairly easy to keep constant, either 

 by running the output of so many gins into the machine or by fitting 

 an effective automatic feed. With a fairly constant pressure in the 

 boiler and a good type of reducing valve there should be no difficulty 

 in keeping the pressure of the steam reasonably uniform. If the 

 machine is driven off the main shaft of the i'actorv. its rate of revolution, 

 and consequently the speed at which the seed travels through the 

 machine, will be constant. And. finally, the quality of the seed will 

 only change at comparatively infrequent intervals. With such a 

 machine, therefore, running continuously and fitted with the proper 

 accessories, the amount of adjustment required should be vcrv small 

 indeed, and an automatic control is barely necessary, all that is 

 reqiiired being an apparatus which will ring bells to warn the operator 

 when the temperature falls too low ur rises too high. Such a, piece 

 of apparatus ca.n easily be constructed, using a pair of Hearson's 

 incubator eapsules. an air them.. a mercury thermometer. 



or any similar device for making the necessarv electric contacts 

 when the temperature rises to one point or sinks to another. 



Another method of controlling the work of the foreman in charge 

 of the machine is to keep a record of the temperature throughout 

 the day's run by means of a thermograph. An apparatus which 

 rings warning bells has been constructed by the Cambridge Scientific 

 Instrument Company, and may be obtained from Messrs. Mosseri. 

 Curie! A: Co.. while a very similar piece of apparatus, with the addition 

 of a thermograph, to which a bell-ringing device could very simply be 

 added, though not originally included, has been designed by .Messrs. 

 C,. Christodoulou and A. Gyzi. of Xifta. 



In those machines in which the seed is heated by a current of 

 hot air the question of control is a more ditlicult one. since, in the 

 list of factors affecting the final temperature of the seed, the steam 

 pressure is replaced by the temperature and the volume of the air 

 passed through the machine. The temperature of the air will itself 

 depend on its own initial tempcra.ture. the temperature of the 



