148 Report on Trials of Plows. 



use of the plow in order that we may be enabled to ascertain 

 what form of the plow is most likely to secure the ends which 

 we have in view. They are: 



Fh'st — To pulverize the soil with a view to promote those chem- 

 ical transformations which will unlock the food of plants from its 

 combinations with unassimilable elements and put it into such a phy- 

 sical condition as will make it accessible to the rootlets of the plant. 



Second — To pulverize it with a view to facilitate the formation 

 of the double silicates. 



Third — That the roots may freely permeate the soil in all 

 directions, thus increasing the range of their pasture. 



fourth — To promote the germination of seeds. 



Fifth — To get clear of stagnant water from the surface. 



Sixth — To prevent the refrigeration of the soil by evaporation. 



Seventh — To secure the return of the water evaporated by the 

 plant in the form of dew. 



Eighth — To destroy the weeds in the soil. 



Ninth — To utilize them and convert them into food for plants. 



All plows known to us press downw^ard upon the subsoil with 

 a weight proportioned to the depth of the furrow slice and the 

 density. This downward action combined with the sliding action 

 of the shares has a necessary tendency to pack the subsoil and to 

 polish the surface. This effect is cumulative, and every succes- 

 sive plowing increases the evil until the bottom of the furrow 

 becomes so dense that neither rain nor air nor the roots of plants 

 can possibly penetrate beneath it. The spade avoids this diffi- 

 culty. Hence, other things being equal, a plow which leaves the 

 bottom of the furrow in the same state in which the spade leaves 

 it would have a very decided preference. 



Guided by the principles which we have now so fully explained, 

 w^e have drawn up a series of practical directions which will be 

 found inserted in the Programme, page 3, under the head of 

 "Duties of Judges," which, if they have been fnlly carried out in 

 the spirit in which they were devised, we believe will settle con- 

 clusively nearly all the questions in practical plowing which have 

 heretofore been left undetermined. 



We have not sought to give a complete and exhaustive enumera- 

 tion of all the objects which the plow is designed to accomplish, 

 such as the mellowing of the soil by frost and the destruction of 

 insects, but only those which involve the peculiar form of the 

 the plow and the principles of its construction. 



