at the York Mectiiir/, 1848. 
403 
desirable that the axles which support the weij^ht shouhl rest on 
a perfectly level bed, and this is accoinj)lished by giving the 
axles so much bend downwards as to make iheir under sides hori- 
zontal. A slight bend is sufficient for this purpose, but, however 
slight, it causes the wheel to lean outwards to the same extent. 
The lean, is, however, so small as only just to throw the balance 
of weight from the cart, and from having attentively watched 
carts with wheels in this position working on the same road with 
others whose wheels were perfectly upright, the writer is of 
opinion that this slight lean gives greater steadiness to the action 
of the wheel. However this may be, the other reason for having 
a slight bend in the axle is clearly an important one, and to 
bring practice to the support of theory, some carts procured for 
the writer by Mr. Laurie of Terreglestown near Dumfries, and 
constructed on precisely the above-mentioned plan, may be quoted 
as having attracted great attention among practical men, from 
their true running and lightness of draught; and after seven years 
very hard work their excellent condition and great favour with 
the carters who drive them are no bad tests of the correctness of 
the principles on which they are constructed. The slight lean 
of wheel above alluded to is not sufficient to make any alteration 
necessary in the cylindrical rim usual for upright wheels ; but 
from observation of the greater ease with which wheels that have 
worn down the edges of their tire clear themselves when running 
in and out of ruts, and with a view to prevent the sucking action 
that takes place with broad flat wheels on wet land, the sug- 
gestion may be hazarded whether a slight rounding of the tire 
might not be introduced with advantage. 
Heic/ht of Cart and position of Shafts. — Before fixing the 
height of carts it is necessary to know the average height of the 
horses which are to draw them, which varies much in different 
districts ; having ascertained this point, the simplest mode of 
proceeding will be to follow out the line of draught from the 
point where the shoulder-chains are attached to the collar, to the 
axle of the cart : in other words, from the point where the power 
is applied, to the place where the resistance has to be overcome. 
The first thing to he attended to is, that the shafts should be fixed 
at such a height by means of the back-band, that when the horse 
is drawing the shoulder-chain and shaft shall be in a straight line. 
If the shaft is too high or too low the chain will meet it at an 
angle, which causes a waste of power. This being done, the 
shaft will represent tlie line of traction or draught, and in the 
remarks which follow, whenever the position of the shafts is men- 
tioned, it must be understood as corresponding with the line of 
draught. Next, let a vertical line be supposed to be drawn 
through the axle of the cart, the power will act to most advantage 
