88 



THE AMERICAN FARMER. 



&quot;What really loosens clay soils by detaching the particles from each other is the act of 

 drying. The ten to twenty per cent, of impalpably fine real clay in such soils, distended by 

 physical hydration, is the glue which sticks their coarser parts together. As the water dries 



GILPIN SULKY PLOW. 



TIMBER LAND PLOW 



out, this cement shrinks around the sand-grains, and must either bring these together into 

 closer contact, or itself crack and break. It does both in fact. A brick just moulded shrinks 

 on drying, and its sides move together. The sides of a field of clay cannot approach each 



THE CASSADAY SULKY PLOW. 



other, and therefore when it dries, r .v jable cracks form over all its surface, and penetrate 

 downwards as the drying deepens. When the soil is so dry as not to be plastic, so that water 

 cannot be squeezed out of a ball of it when worked in the hand, and so that when thrown up 



