OPERATIONS OF TILLAGE. 



125 



** By means of this instrument the earth is to be turned 

 over to a given depth ; and this is to be effected by cut- 

 ting from the ground successive sods or sHces of earth, 

 so that each sod or shoe shall be raised up or turned over, 

 in such a manner that an entirely new surface shall be ex- 

 posed to the atmosphere." 



In this mode of laying the furrow, it will be perceived, 

 the largest surface is exposed to the enriching influence 

 of the atmosphere — viz., one entire edge, and most of 

 both the upper and under surfaces of the furrow-slice. 



In fig. 14, let A B C D represent the end or trans- 

 verse section of the slice of earth which is to be turned 



over. 



Fig. 14. 



Fig. 15. 



Fiff. 16. 



The slice is first to be raised from the position in which 

 it Hes in fig. 14 ; it is next to be placed in the position 

 shown in fig. 15, and it is finally to be placed in that 

 represented in fig. 16. 



" In the following diagram, fig. 17, let A B C D, 

 corresponding with the same letters in the last figures, 

 represent a transverse section of the slice of earth which 

 is to be turned over. This slice is first to be raised from 

 its horizontal position A B C D, by being turned upon 

 its corner C as a pivot, and placed in the position 

 C E F G, corresponding with that of fig. 15 ; it is then 

 to be turned upon its corner G, as upon a pivot, and laid in 

 11* 



