On Harrowing W heat. 11 
by repeated ploughings and harrowing each time, all 
the seeds which may be in the soil being brought to 
vegetate, will be completely destroyed. 
I have often advised some of my friends in the coun- 
try, to try this method of harrowing their grain.—I 
reasoned with them by analogy from the well known 
practice of harrowing their meadows in the spring; if 
the operation of harrowing grass meadows causes the 
grass to assume a dark green colour and vigorous 
growth, why may not the same effect be expected upon 
the grain. Ihave often thought that by repeated ex- 
periments of this kind, accompanied with minute ob- 
servations, the hessian fly at certain periods of its exist- 
ence, might be much disconcerted, if not destroyed ; 
at any rate by giving the grain a start, it might out- 
reach in some measure the depredations of the fly. 
My friends would listen to my reasoning, and even 
acquiesce with my ideas, but when I enquired if they 
had made the trial, the excuse was they had not got a 
light harrow, or they had too much work to spare time 
for experiments, so hard is it to introduce any improye- 
ment though ever so valuable. But I am fully convinced 
that if the practice were to become general, the effects 
would be found equal if not superior to the valuable 
effects which have been produced by plaister of Paris. 
See our Memoirs, vol. 1, page 88. 
