WHEEL. 
is called wharfage, and the person who has 
the direction and oversight of the wharf, 
receives wharfage, &c. is called the w^r- 
linger. 
WHEAT. See Triticum. 
WHEEL. This is one of the six powers 
of mechanism; and without doubt, contri- 
butes more than any of the other five to the 
general conveipence of mankind ; by the 
wonderful variety of purposes, from a mill 
to a watch, wherein it is employed. It is 
our intention, however, in this place, to 
confine ourselves to the wheel as apper- 
taining to vehicles in general, referring the 
readers to the articles Mill rmfe. Watch 
work, Clock work, &c. tor the application 
of such wheels as come within those 
branches of the arts. 
Of carriage wheels, in general, we shall 
then treat ; observing, that any attempt to 
prove that a carriage is more easily drawn 
upon wheels than upon sledges, would be 
an aft’ront to the understanding of the 
reader. But whether high, or low, wheels 
are fitted for the purpose, has been a sub- 
ject of dispute, even among persons of 
skill. Reason and experience, however, 
seem perfectly to agree in this, tliat wheels, 
whose centres are on a level with the 
moving power, will be easiest drawn along 
a level plane ; and that the higher a wheel 
is the more easily will it get over the ob- 
stacles it may meet with, provided the 
moving power be not below the centre. It 
seems to follow, therefore, that carriages 
drawn by honses, or oxen, should have 
wheels whose centres have the height of the 
draft line ; that is, of the shoulders of the 
horses, or the yokes of the oxen. This is 
true, however, only in the case of a horizon- 
tal road ; in going up hill the distance of the 
line of draught from the road is somewhat 
less ; because, when a man, or any other 
animat, is standing upon the side of a slope, 
his height is inclined to that slope ; or ra- 
ther the slope is inclined towards him, where 
he stands perfectly perpendicular. This- 
being the situation in which cattle labour 
most, it is necessary to proportion the draft, 
so as to render it as light as pos'sihle while 
drawing up hill ; therefore, it is usual, and 
highly proper so to proportion the height of 
the axle, especially in carts with two 
wheels, to the point of draught, that the line 
drawTi from the centre of the wheel to that 
point, should rise at an angle of about 
twelve or fourteen degrees ; thus, when 
the horse is lal>oui*ing up hill he will come 
nearly to a level with the wheel’s centre, 
VOL. VI. 
and draw to the greatest advantage. This 
may serve as a general rule ; but where 
local circumstances prevail of a different 
tendency, and also in particular cases, the 
height of ihe wheels must be suited to meet 
such. We reckon that in ordinary work, 
and where the horses do not exceed the 
height of fifteen hands and a half, the 
wheels should be from four feet eight inches 
to five feet two. Yet the immense loads 
drawn in the coal caits at Glasgow, on 
wheels more than six feet high, and other 
instances of a like kind, prove that very 
great powers are gained by using high 
wheels ; under due construction and appli- 
cation the difference of the wheel’s weight 
will not prove any material drawback. In 
ascending, high wheels will be found to fa- 
cilitate the draught in exact ratio witfi the 
squares of their diameters ; but in descend- 
ing they are liable to press in the same 
proportion. An admirable device was pro- 
duced by Lord Somerville, for throwing the 
weight behind the centre in going down 
hill, by cocking the fore part of the body of 
a cart ; so that while the shaft may incline 
downwards, in proportion to the line of de- 
clivity, the bottom of the cart’s body should 
remain horizontal ; this construction is now 
common in Devonshire, Somerset.shire, &c. 
Wheels are commonly made with wliat is 
called a dish ; that is, the spokes are set at 
an angle into the nave, or centre-piece ; so 
that, when the interior end of the nave is 
placed on the ground, the wheel may ap- 
pear to be dished, or hollow, in the centre. 
Experience has shown, that when wheels 
have been made cylindrical, and not with 
the conical hollow just described, so that 
the spokes stood at right angles with the 
centre of the axle, numberless inconve- 
niences arose; the dirt taken up by the 
wheel used to fall in between the nave and 
the axle, so as to choak and Wear it consi- 
derably. Such wheels also required to 
stand wider apart, and demanded greater 
road way ; besides they were very apt to be 
wrenched when pressed by any exterior re- 
sistance, and the spokes were forced back 
in the mortices. According to the present 
plan of dishing wheels, usually to about four 
inches in five feet of diameter, the exteriof 
resistances are avoided; the axle being so 
turned down at its ends, as to cause the 
lower spoke, which bears up the load, to 
stand perpendicularly under the centre ; 
thus occasioning the upper parts of the 
two wheels on the same angle to spread 
from each other ; while the lower parts con- 
O 0 
