264 



Cultivation of the Hop Crop. 



[June, 



In America closed kilns are everywhere used; they are 

 generally built of wood and are higher than the usual English 

 type of kiln. In England stove kilns are generally operated by 

 artificial fan draught, the best known type being that designed 

 by E. G. Shew, of Herefordshire.* 



These stove kilns, as stated above, enjoy the great advantage 

 of cheap fuel. In the Boyal Agricultural Society's trials referred 

 to below, it was shown that on the average of the season 

 the output of dry hops per 1 cwt. of coke consumed was exactly 

 1 cwt., which compares favourably with the weight of anthracite 

 coal commonly required for hop drying, generally regarded as 

 between f and 1 cwt. per 1 cwt. of dry hops, especially when 

 the cost is taken into account. 



The disadvantage of these systems is the extra capital involved 

 and the rapid wear and tear to which the stove and pipes are 

 subject. The labour involved in stoking such kilns is not greatly 

 different from that in the open-fire kilns; the installation, there- 

 fore, of some such stove-kiln system is well worth the considera- 

 tion of any grower who contemplates the erection of new oasts. 

 The decision can be based upon prices prevailing at the time. 



Other forms of hot-air drying have been tried in which the 

 drying air has been caused to pass through a battery of pipes, 

 heated sometimes by steam and sometimes directly from the 

 products of combustion, situated outside the kiln. These types 

 have not made much headway probably because of the inevitable 

 wastage of heat involved. 



Fan- draught. — The fan method of controlling draught has 

 been applied both to stove kilns and to open-fire kilns in a variety 

 of ways, and undoubtedly gives the drier absolute control in the 

 oast. A drier provided with fan-draught and with thermometers 

 should make no mistake, provided he takes reasonable precau- 

 tions. There are several possibilities in the method of driving 

 and utilising the fan ; it may be belt driven or electrically driven 

 and it may be placed above or below the hops. If the fan is belt 

 driven it is generally situated below the hops to drive air into 

 the kiln because it is more convenient to fix and drive in this 

 way. When the fan is fixed below it is most important to pro- 

 vide adequate openings above the hops for the escape of the air 

 since otherwise the fan is working against unnecessary resistance, 

 but when kilns that have served for open-fire methods are con- 

 verted, it not infreq uently happens that this provision is omitted. 



* An account of this and three other types of hot air kilns is given in 

 a The Trials of Hop Drying Plant" in the Journal of the Royal Aqricultvral 

 Society for 1909. 



