412 On the Buhr-stone of Halkin Mountain. 
No. II. 
Mirfield Low Mills, March 7, 1821. 
Sir,—After having tried your Halkin buhr-stones, for a fair 
and sufficient time, we are now enabled to lay before you a can- 
did and faithful report of their quality; and this we shall endea- 
vour to do, with as much brevity as is consistent with the im- 
portance of the subject. 3 3 
The perfection of grinding consists, in reducing grain to a re- 
quisite degree of fineness, with the least pressure; or, in other 
words, to make the best and the greatest quantity of flour, out 
of a given quantity of wheat, with the least pressure. But, the 
mere good quality of a stone cannot effect this; for we must 
now call in the aid of art. And here it is that the great art of 
a miller.consists, the putting of work into stones, or the obliquity 
and disposition of the furrows, every thing else compared with 
this being only trifles. And, indeed, when we consider that an 
accurate knowledge of this is grounded upon the doctrine of cen- 
tral forces, which constitutes an important branch of the New- 
tonian philosophy, we need not wonder that so few understand 
the real principles of corn grinding. We have, however, rea- 
sons to believe that we have considerably improved it. 
From these observations it appears, that though the quality 
of the stones may be equally good, the effects produced will be 
different, according as the work is scientifically put in or other- 
wise; but, if the work and velocity of the stones be the same, 
we can clearly ascertain the quality of them by the effects pro- 
duced. 
We will now apply these observations to the stones in ques- 
tion. After twice or thrice taking them up, we were afraid that 
they would not stand the crack well; but this fear was soon 
dispelled, as we now find that they wear exceedingly little, and 
that the crack stands as fine as a hair. We now proceeded to 
ascertain the quality of the bran compared with our French 
stones, and for this purpose, we sifted the meal from every pair 
of stones as it came from the mill-eye; the bran thus retained 
in the sieve, we placed by itself, and by this means we had an 
opportunity of comparing the whole together. This we have 
repeated no less than forty times, and the result has always been, 
obviously from the very first glance, that the bran produced from 
the Halkin buhrs was not only cleaner, but of a more uniform cut; 
and this has not been perceived by millers alone, but by every 
person that has accidentally come into the mill. 
This we think is quite sufficient to prove the superiority of 
the Halkin buhrs; but, that every possible doubt might be re- 
moved, we had recourse to the following experiment : 
We 
