MILL. 
/, by which the miller can draw it : fc is a 
beam across the pen-trough ; and, k an iron 
bolt to support the bottom of the trough ; 
the edge of the hole over which the water 
runs, is the distance of one bucket beyond 
the perpendicular line going through the 
centre of the wheel ; and it is formed of 
iron plate, with a sharp edge, to avoid drop- 
ping ; the edge of the shuttle is also cover- 
ed with iron plate, that the water may be 
delivered clean and in one entire sheet. 
The first-mentioned iron plate is bent so as 
to deliver the water nearly horizontally. 
The wheel is inclosed in a close breasting 
of stone, D D. 
Attempts have been made to construct 
water-wheels winch receive the impulse ob- 
liquely, like the sails of a common wind- 
mill. By this means a slow but deep river 
could be made to drive our mills ; though 
much power would be lost by the obliquity. 
.Dr. Robison describes one that was very 
powerful; it was a very long cylindrical 
frame, having a plate standing out from 
it, about a foot broad, and surrounding it 
with a very oblique spiral, like a cork- 
screw. This was immersed nearly a quarter 
of its diameter (which was 12 feet), having 
its axis in the direction of the stream. By 
the work performed, it seemed more power- 
ful than a common wheel that occupied the 
same breadth of the river. Its length was 
not less than 20 feet ; had it been twice as 
long it would have nearly doubled its 
power, without occupying more of the 
water-way. Perhaps such a spiral continu- 
ed quite to the axis, and moving in a suit- 
able canal, wholly filled by the stream, 
might be an advantageous way of employ- 
ing a deep and slow current. 
An under-shot mill, with oblique float- 
boards, was invented by the late Mr. 
Besant of Brompton, it promises to be of 
great service in some situations. In com- 
mon water-wheels more than half the quan- 
tity of that fluid passes from the gate through 
the wheel withotit affording it any assistance : 
the action of the floats is resisted by the in- 
cumbent atmosphere, at the moment when 
these leave the tail-water ; and, as a similar 
proportion of water, with that which passed 
between the floats and the head, necessarily 
flows between them at the tail, the motion 
of the wheel is greatly impeded. On the 
contrary, by Mr. Besani's contrivance, no 
water can pass except tliat which acts with 
all its force on the extremity of tire wheel ; 
and, as the floats emerge from the water in 
an oblique direction, the weight of the at- 
mosphere is thus prevented from taking any 
effect. A great advantage of this construc- 
tion is, that the wheel works lighter, owing 
to a tendency to floating. AVhen working 
in deep tail-water it is decidedly superior ; 
carrying weight in the proportion of three 
to one. 
Messrs. Polfreenian and Co. lately pur- 
chased the patent-right given to Mr. Haw- 
kins for his invention of floating water-mills, 
and established one, by permission of the 
Board of Navigation, on the Thames. This 
kind of mill might be more generally used, 
with great advantage to the public ; and, in 
lieu of being constructed as tide-mills (wliicli 
require that the work should all revolve 
either with or against the .sun), would, per- 
haps, be something improved by allowing 
the hulks, in which they are built, to swing 
round, like ve.ssels at single anchor, in the 
tide’s way. 
Mills, mnd, are, in their general con- 
struction, much the same as watermills; 
adverting to the difference of the power by 
which they are acted upon. The external 
apparatus consists chiefly of the sails, or 
vanes, which are commonly four, placed in 
nearly a vertical position, and giving, as 
they turn, a rotatory motion to an axis in- 
clining but little from the horizon. The 
form of the arms and vanes being so well 
known, we shall refrain from describing 
them in this place. 
The direction of the wind being ex- 
tremely uncertain, it becomes necessary to 
have some contrivance for turning the sails 
towards it : for this purpose two modes are 
in more general use. In one, the whole 
machine is sustained upon a moveable ar- 
bor, or axis, perpendicular to the horizon, 
and supported by a strong stand, or foot, 
very firmly fixed in the earth : thus by 
means of a lever the whole may be turned 
round to any direction. In the other way, 
only the upper part is moveable ; the roof 
being a kind of cap joining to the axis on 
which the sails, or vanes, are fixed, and 
working round by means of an endless 
screw, that acts upon a ratchet frame, em- 
bracing the lower part of the cap. The 
former mode applies chiefly to what are 
called post-mills ; the latter, to fixed-mills, 
built of masonry. 
We offer the following table of velocity 
and power, resulting from the experiments 
of Blr. Smeaton, and confirmed by Dr. Hut- 
ton, Mr. Rouse, &c. By it our readers 
will be able to compute to any extent, 
when on the subject of the wind’s progress. 
