166 CULTURE OF FARM CROPS. 



centre being frequently found soured and heated highly, 

 while those portions near the outside of the mass are un- 

 injured. It is also the case in hay or other substances of 

 a similar nature." Such, then, is the theory ; the practical 

 method of obviating the evil deduced from thence is very 

 simple. Take out the centre mass, or insert a tube or series 

 of tubes in the centre of the receptacle in which the flour 

 &c., is contained, and the difficulty is met. What the con- 

 sequence of this simple contrivance is, a brief investigation 

 will show. Suppose a barrel of dry sponges, having in the 

 centre thereof a series of sponges saturated with moisture 

 extending from top to bottom of the barrel, there will thus 

 be a core of wet in the midst of the dry sponges. Accord- 

 ing to the theory above noted, the wet will radiate from 

 the centre mass outwards in all directions, and the sur- 

 rounding mass will become gradually saturated. As there 

 is no obstacle in any direction to these radiations of wet, we 

 can suppose the process to go on by adding a series of 

 concentric rings of wet progressing towards the external 

 barrel. It is riot at all likely that the wet will progress 

 only on one side of the wet central mass, thus forming one 

 semicircle of wet and another semicircle of dry sponge ; 

 it is just as natural for the wet to go to one side as to the 

 other, and seeing that there are no obstacles to its doing so, 

 the almost absolute certainty is that it will go to all sides. 

 In the centre of the barrel place a tube ; the consequence 

 is, that the wet mass is displaced to one side only, and be- 

 fore the damp or unsoundness can reach to the opposite 

 side of the tube and the material there placed, it must per- 

 force travel round the whole circumference of the tube. 

 But to travel in this way the wet must progress in a lateral 

 direction, and we have already shown that it radiates from 

 a point like the spokes of a wheel ; its progress, therefore, 

 will be mainly outward towards the barrel. By this ar- 

 rangement, therefore, only a minimum portion of the mass 

 is damped, and the chances are that before all the mass 

 round the central tube gets damp which must necessarily 

 be a slow process, as each damp portion will only, like its 



