1310. 
vection with the roller, The malt, or 
other substance, to be ground, passes be- 
tween the rollers and the cutters. ‘There 
is an adjusting screw to keep the rol- 
Jer at a proper distance from the knives. 
There are two levers that act against 
the brasses of the hearing of the roller, 
and keep the roller up to its work. 
A farther use of these levers, is to admit 
and allow the roller to rise up, when any 
thing gets between it and the knives, 
that by its hardness might injure the one 
or the other, and let it pass through ; the 
roller will then fall into its former sta- 
tion. There are weights made to slide 
on the levers, so that they may be ad- 
justed, and more weight not permitted to 
act against the roller than is sufficient to 
keep it to its work. The roller and 
cutters are worked upon a carriage, 
which carriage may be made of divers 
forms. Besides the figure already de- 
scribed, there are others exhibiting the 
spindle, to which the moving-power is to 
be applied; the sliding brasses for the 
roller. to work in; the double-wired 
screen, to take the rubbish and dust from 
the malt, or other matter. The upper 
Wire is coarse enough to let the malt, or 
other matter, through, and the bottom 
one to take out the dust. There is a 
beater fixed on the screen to act against 
projections on the roller, to give motion 
to the screen to shake the malt, or other. 
matter: there is also a spout to clear 
the top screen of the rubbish, and a 
hopper fixed at the top of the screen, in 
which is put a wire to take out the 
thickest of the rubbish, 
Sie . 
MIR. STEPHEN HOOPER’s, (WALWORTH,) 
for a Thermometer for ascertaining the 
Heat of Bakers’ Ovens,and various other 
purposes. . 
The principle of this instrument con- 
sists in the comparative degree of expan- 
gion, or contraction, which takes piace 
in different substances, when these sub- 
stances are exposed to different degrees 
af temperature; and, in order to reduce 
this to practice, the instrument is con- 
structed as follows, which we shall give 
in the patentee’s own words: “ 1 make 
use of two rods, bars, or tubes, of: any 
convenient leigthand shape; and the sub- 
stances of which these rods are made are 
such, that one of them is susject to a 
greater degree of expansion or contrac- 
tion than the other, when exposed to dif- 
ferent degrees of teniperature; or, in other 
words, I chuse such substances, that one 
4 
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‘4 : Paitenés lately Enrolled. bi 
4435 
of them may be subject to as little, and 
the other as much, variation in length as 
possible, when heated or cooled ; posses= 
sing at the same time such other proper- 
ties as render them of convenient appli« 
cation. Ido, therefore, generally make 
use of brass and wooden rods, or, as be- 
ing more convenient, a brass tube and 
wooden rod, which are hereinafter more 
particularly deseribed as follows: that is 
to say, | make a brass tube of any con- 
venient length and diameter. The lengt!:. 
of the said tube I generally make equal 
to the length of the oven to which the 
thermometer is intended to be applied, 
and about an inch and a quarter in dia- 
meter. Into the said brass tube EF intros 
duce a wooden rod, made of fir, or any 
other -very straight-grained woods the 
wooden rod being nearly of the same 
length as the brass tube, and of such a: 
diameter as to slide freely backward and 
forward in the brass tube without stick 
ing. The said brass tube and wooden 
rod, are firmly fixed to each other at on 
end, so that if any expansion or contrac 
tion arising from a change of tempera- 
ture, takes place in the brass tube, that 
change of temperature. will be indicated 
at the other end by the increase or 
decrease of the length of the brass tubes. 
when compared with that of the wooden 
rod, the said rod having, a scale. fixed 
thereon for that purpose. But as the 
divisions upon the said scale, when so 
contracted, are tceo minute to be easily 
made, ot distinctly observed, I prefer a 
scale with larger divisions, which I ob-. 
tain by applying a lever, or a combinae. 
tion of levers, according to the well. 
known methods now in use for. construc- 
ting pyrometers, or by arack and pinion ;. 
in which case [ affix a rack to the end of 
the brass tube, and cause the said rack 
to turn a small pinion; and upon the axis 
af the said pinion I place a hand, or 
index, which points the degree of expan- 
sion or heat upon acircular plate, pro<. 
perly divided. The said pinion and 
plate, in which the axis of the pinion. 
turns, are afiixed to the wooden rod,” 
Mr. Hooper next describes the mode 
of using his thermometer, when applied 
to bakers’ ovens: that is, he causes a 
channel, or hole, to be made in the bricke 
work, about six inches below, and paral- 
lel with the bottom of the oven, extend- 
ing from the mouth to the farther side of 
it, in such a direction as that a vertical 
plane passing through the channel, would 
nearly bisect the oven door, The instru~. 
mere 
. 
