618 The Trials of Grist Mills and Disintegrators at Plymouth. 
The grinding rings are placed vertically within a strong 
wrought-iron cylindrical chamber, to which one annulus is 
bolted while the other revolves at the rate of 800 turns per 
minute. Adjustment is made, for fine or coarse grinding, by 
means of a set screw at one end of the spindle, operating 
against the opposing pressure of a spiral spring at the other 
end of the shaft, which itself is driven, without countershafting, 
by belt direct. AW the moving parts of the mill are placed 
between the bearings, which are very long and adequate. 
Only three pairs of grinding discs, " coarse," " medium," and 
" fine," are employed in ranging from the coarsest to the finest 
work. They are of cast metal, having the teeth deeply chilled, 
are ground together with emery for the purpose of trueing up, 
and cost 21. per pair, lasting from four to six months, according 
to the work. This machine is well designed and constructed, 
the workmanship and materials being first-class throughout. 
It occupies an over-all floor-space of 6 feet 3 inches x 3 feet 
3 inches, and weighs 18 cwt. 
After a short preliminary run, of which no notes were taken, 
the mill received 5| cwt. of bones, which was finely ground 
(less cwt. of material rejected by the operator as too large) 
at the rate of 13 cwt. per hour. Over-anxiety about the fine- 
ness of his sample spoiled the " Devil's " time on the first run, 
but a second dose of bones was disposed of at the rate of 1 ton 
per hour, while the sample still remained excellent. The 
machine next received 5 4 cwt. of cotton-cake, which was finely 
ground at the rate of 48 cwt. per hour, the draught in the case 
both of bones and cake being moderate. Reference is made, in 
the case of all the disintegrators experimented upon, to Table VI. 
(page 02 3) for a comparative statement of time, draught, &c. 
The mill worked with great steadiness, and was easily fed by 
one man. » 
The system of grinding adopted in the " Devil " disintegrator 
deserves some consideration. It combines the percussive action 
of what has been called the " Collision " mill with a shearing 
action which, progressing step by step, gradually reduces the 
material to be operated upon to any required degree of fineness. 
Meanwhile, although nothing can escape from the mill until it 
has reached the predetermined fineness, there is practically no 
re-grinding, and no loss of power from that cause. Again,. the 
shearing action of the intermitted teeth, each upon the other, 
enables the machine to operate, whether upon wet or dry, brittle 
or tough, fibrous or non-fibrous materials. There are, probably, 
no substances, metals excepted, which could not be disintegrated 
by this machine, and its power to pulverise a great variety of 
