70S MECHANICS. 
deep well. This would be an hydraulic machine exceed¬ 
ing all others in fimplicify and durability, though inferior 
in eft'eCt to feme other confti uCtions. 
The late Mr. John Smeaton, F. R.S. was celebrated for 
his accuracy and judgment in the proportions of his mills, 
particularly thole turned by water. We (hall therefore 
defcribe an overlhot flour-mill, which was ereCted from 
his defigns, at the viCtualling-lioufe for the navy at Dept¬ 
ford, in 1781. Fig. 107. reprefents the whole mill, by a 
longitudinal feCtion of the houfe; and fig. 108. another 
feCtion, taken perpendicular to the former. The mill is 
double; that is, the water-wheel, A A, is fituated be¬ 
tween two buildings, only one of which is reprefented in 
fig. 108. and the wall, B B, of the other, is one fide of a 
houfe, containing exactly the fame machinery as that 
.which is delineated. Over the water-wheel two large 
citterns, or troughs, C, D, are placed, communicating 
with each other by a large iron-pipe E, (fig. 107.) and 
one of thefe troughs, C, has a pipe or trough, leading 
water into it, from the pump of a fleam-engine which 
fupplies the water for the mill ; in the other trough, D, 
is a (buttle rz, which, being raifed up, permits the water 
to iffue from a hole in the end of the trough, and fly for¬ 
wards horizontally through a proper finite, or pentruugh, 
into the buckets of the wheel A. The form of thefe 
buckets is fliown, by a portion of the wheel reprefented 
in feCtion for that purpofe. The buckets, which are thus 
filled at the top of the wheel, defeend by their weight, 
turning the wheel round, till they come to the lowelt part 
of the wheel ; and here, by the buckets becoming inverted, 
the water is difeharged from them, and they go up empty 
to the top of the wheel, where they are filled again from 
the trough. In this manner, one fide of the wheel being 
always loaded by the buckets full of water, and the other 
fide being empty, it has a conflant tendency to turn round. 
The axis of the wheel has a large fpur-wheel, T, fixed 
upon its extreme end, which being-furnifhed with a dou¬ 
ble row of cogs, as fliown in fig. 1.08, communicates mo¬ 
tion to the lanterns or trundles, F, G, one above and the 
other below it; the latter, G, is fixed upon the end of an 
horizontal draft H, extending beneath the millflones, 
fituated at I I and L: it aCluates the upper (lone of each 
pair, by means of crown or face wheels K K K, which 
turn the pinions fixed at the lower enus of the refpeCtive 
fpindles dd. The foot of the fpindle reds in a brafs 
focket, fixed in a lever w, called the bridge-tree ; its ful¬ 
crum is in the folid wall, W, fig. 107, at one end, and 
the other reds.on the middle of a fecond lever X, perpen¬ 
dicular to the former, called the brayer, one end of which 
has a fulcrum in the framing, fig. 108, and the other is 
fupported by a ferew, which the miller turns round, to 
elevate or deprefs the upper done, and adjud the didance 
between them at pleafure, according as he wifhes to grind 
finer or coarfer flour. The upper trundle, F, is fixed upon 
a fliaft, which carries two face-wheels, c,f\ the teeth of 
thefe wheels are oppofite to each other, and either of them 
can be made to work a pinion, g, fig. 107, fixed upon the 
end of an axis h, which at the-other end has a cog-wheel 
turning a pinion at k, on the end of the fpindle of a ma¬ 
chine, M, for drefling flour. This machine confids of a 
hollow cylinder or frame, covered with wire-cloth of dif¬ 
ferent degrees of finenefs ; the fined being at the end A, 
which is the mod elevated ; every one of the lengths, as it 
goes towards the other end, is covered with a coarfer kind 
of wire-cloth, for fifting the flour. Within this cylinder, 
which is flationary, a reel is fituated; its axis being ex¬ 
actly in the centre of the cylinder, and turned round by 
t he pinion k ; the rails of this reel are provided with hair 
brufhes, which, as they revolve, brufh againd the interior 
wire furface of the cylinder. The machine is provided 
withaftioe or jigger, very fimilar to that of the millflones, 
to bring down the flour or meal through a trough, from 
the floor above, where it is kept after being ground: the 
meal, being by this means gradually fed into the cylinder, 
is, by tlie motion of the brufhes on the reel, lifted or rub¬ 
bed through the wire; the fined of the flour will of courfe 
go through at the upper end, but no other kind; the fe¬ 
cond through the next divifion, and fo on till the bran falls 
out at the end of the cylinder, being too coarfe to go 
through any of the wires. The cylinder is enclofed in a 
tight and clofe box M, to prevent wade by the flour fly¬ 
ing about; and the box has partitions, which divide it 
into as many lengths as the cylinder has different kinds 
of wire. Thus each divifion of the box receives a diffe¬ 
rent quality of flour; and fpouts being fixed, which go 
down into the floor beneath, facks can be filled at them 
without wade or inconvenience. The piniong, for turn¬ 
ing the drefling-machine, can be made to turn either way, 
by engaging it with the teeth of either of the cog-wheels 
e, f, which, aCting on the oppofite Tides of the pinion g, 
give the means of turning it in either direction at pleafure. 
The pinion is of l’uch a diameter, that it cannot be en¬ 
gaged with both wheels at once; and the upright lever r, 
which fupports the pivot of its axis h, can be thrown to 
either fide, as is fliown in fig. 108. for its lower end moves 
on a centre at the floor, and at top it is guided by a groove 
in a piece of wood, fixed to the ceiling, and can be faf- 
tened at either fide by a pin, fo as to throw the pinion in 
gear with either e or/. The objeCT of this contrivance is, 
that, when the machine M has for a long time been run¬ 
ning in one direction, and its bruflies become worn, or 
bent on one fide, its motion may be reverted, to give them 
an equal wear on the oppofite fide. The wheel, e, has 
another fixed to it at the back, (fee fig. 108.) which ac¬ 
tuates a cog-wheel N, upon the end of a roller, having a 
rope wound round it, for drawing up facks of corn or 
flour from one floor of the mill to another. This rope 
pafles upwards from the roller to the roof of the building, 
where it pafles over a pulley, and thence defeends through 
fquare holes in the feveral floors to the ground. Thefe 
holes are covered by double doors, opening upwards, 
fo that a fack, being drawn up, opens the door, which 
falls down as foon as it has palled. The wheel N of the 
fack-roller can be difengaged at pleafure from the cog¬ 
wheel e, which turns it ; and then the rope can be un¬ 
wound and run down again, to fetch up another fack. 
Figs. 109, 110, explain the conflruCtion of the cad- 
iron axis for the water-wheel. N is the cylindrical fliaft, 
and k, h, its two necks, which lie on bearings in the wall 
of the mill, and bear the weight ; beyond thefe necks the 
axis has a fquare box, O O, at each end, for framing the 
great cog-wheels upon. The manner of attaching the arms 
of the great water-wheel to the fhaft is this : Two circular 
plates or flaunches, P, P, are cafl upon the axis; and, 
againd each of thefe, twelve arms, Q, Q, are bolted ; they 
are placed againd the flaunch, tending to the centre, and 
the fpaces between them are filled up by wooden pieces, 
as fliown by r, r, r, fig. no. two iron rings, R and S, are 
placed over the arms, and a bolt put through each arm, to 
attach it to the flaunch and to the axis; the wooden 
pieces, r, r, are kept in their places by a wedge driven 
through each, with the great hoop R ; and, by means of 
thefe wedges, the pieces r, r, can at any time be drawn up 
towards the centre, to hold all the arms fad in their places. 
This method of framing water-wheels was ufed with great 
fuccefs by Mr. Smeaton in many indances, and was found 
to anfwer the purpofe extremely well, being a great im¬ 
provement upon the old method of mortidng the arms into 
a wooden fliaft. 
Of Floating Water-mills .— Although we are in this coun¬ 
try provided with many contrivances, in which the dif¬ 
ferent powers of water, fleam, wind, and animal force, 
have been fuccefsfully applied to the purpofe ot grinding 
corn into flour, yet we have not, till very lately, met with 
floating water-mills to be worked by tides or currents ; 
and which are further defigned to put in motion machinery 
adapted to any kind of manufacture. MefTrs. Polfreeman, 
of Long-acre, in conjunction with MefTrs. Allen, Foflenden, 
and Gray, have purchafed the patent-rightof Mr. Hawkins, 
and have lately completed one of thole mills, which, by 
•1 permiffion 
