ROTATION OF HIGHEST INCOME. 207 



of some extent, and the demand for produce uncertain, it is 

 always desirable to make the change gradually, so as either to 

 spread the extra supply of produce over a number of years, or 

 to accumulate the extra growing stock gradually, thus disturbing 

 the market as little as possible. 



2. Rotation of the Highest Income. 



By this is understood the rotation which yields the highest 

 income, calculated without interest and irrespective of the 

 time when the items of income occur. The net income is 

 thus calculated according to the arithmetical mean of incomes 

 diminished by the costs. All items of income and costs during 

 one rotation are added up, and the sum of the latter deducted 

 from the former; the difference, divided by the number of 

 years in the rotation, represents the annual income. 



Hence, the rotation in this sense is that under which the 

 expression 



Y r +T a +T b + . . + T 9 -c-rxe 

 Annual income = - J/ - 



r 



becomes a maximum. 



As the annual expenses and the cost of formation are 

 generally the same for differing rotations, the above expression 

 can be reduced to the following : 



Gross annual income = j r r+ r + r + ' ' + T <*. 



r 



This rotation falls, as a rule, a number of years beyond the 

 financial rotation. 



Example. Taking the data contained in the table at page 

 202, the net annual income amounts to : 



For a rotation of : 



Shillings. 



2130 + 4 + 36 + 67 + 86 + 91 + 95-60- 



orv *^^ X O Of7.M 



80years = - =27'61 



