Variations of the Four-coarse System, 
291 
the sheep twice a week over a dry floor which is covered with 
powdered lime, or through a trough containing a solution of one 
part of carbolic acid w'ith fifty parts of water in which a little 
soft soai? is dissolved. Sufficient fluid should be kept in the 
trough to insure that the feet are completely covered. 
Prevention can only be secured by avoiding the introduction 
of diseased sheep on to the farm, and also the prevention of con- 
tact between healthy and diseased sheep, and with contaminated 
ground; — a system which, if carried into effect, would entirely 
alter the customs of the sheep trade, as every farmer would be 
compelled to make his flock self-sustaining, and under no cir- 
cumstances could he introduce on to his farm sheep from a fair 
or market, nor indeed from any source, until he had assured 
himself that they were quite above suspicion. 
G. T. Brown. 
VARIATIONS OF THE FOUR-COURSE 
SYSTEM. 
The “ four-course system,” or Norfolk rotation, embracing the 
familiar succession of Turnips, Barley, Clover, Wheat, has been 
subjected to a long and exhaustive trial,by the cultivators of this 
country. It has been advocated by enthusiastic supporters, 
depi’ecated by others whose soil and climate were unsuited to its 
practice, and, most imjDortant of all, it has been judiciously 
modified by yet a third class of cultivators, who, whilst not 
accepting it as a final resort, saw in it much that was useful 
and commendable. No subject has afforded a more fertile theme 
for discussion by those whose business it is to till the soil, and 
so recently as the early months of the present year it furnished 
the material for a two nights’ debate upon a paper, “ The Four- 
course System, with desirable Variations,” read by Mr. E. H. 
Morris before the Surveyors’ Institution. The essential part 
which the turnip crop has taken in the practice of the four- 
course system leads me to devote a few preliminary remarks 
to it. 
It appears that the turnip plant was known to the ancients, 
for Columella frequently recommends the cultivation of rapa as 
food for both man and beast. The cultivation of the root in 
England is first recorded about the year 1645. Writing in 
1686, Ray says turnips were sown for the growth of their roots 
