ry excellent ones now on the market, is provided with
anti-friction roller bearings, which lighten the draft considerably.

Every stone road, unless properly built with small stones and just
enough binding material to fill the voids, presents a honeycombed
appearance. In fact, a measure containing two cubic feet of broken stone
will hold in addition one cubic foot of water, and a cubic yard of
broken macadam will weigh just about one-half as much as a solid cubic
yard of the same kind of stone. Isaac Potter says:

"To insure a solid roadway and to fill the large proportion of voids or
interstices between the different pieces of broken stone, some finer
material must be introduced into the structure of the roadway, and this
material is usually called a binder, or by some road-makers a 'filler.'

"There used to be much contention regarding the use of binding material
in the making of a macadam road, but it is now conceded by nearly all
practical and experienced road-makers, both in Europe and America, that
the use of a binding material is essential to the proper construction of
a good macadam road. It adds to its solidity, insures tightness by
closing all of the spaces between the loose, irregular stones, and binds
together the macadam crust in a way that gives it firmness, elasticity,
and durability."

Binding material to produce the best results should be equal in hardness
and toughness with the road stone; the best results are therefore
obtained by using screenings or spalls from the broken stone used.
Coarse sand and gravel can sometimes be used with impunity as a binder,
but the wisdom of using loam or clay is very much questioned. When the
latter material is used for a binder the road is apt to become very
dusty in dry weather, and sticky, muddy, and rutty in wet weather.

The character of the foundation should never take the place of proper
drainage. The advisability of underground or subdrainage should always
be carefully considered where the road is liable to be attacked from
beneath by water. In most cases good subdrains will so dry the
foundation out that the macadam construction can be resorted to.
Sometimes, however, thorough drainage is difficult or doubtful, and in
such cases it is desirable to adopt some heavy construction like the
telford; and, furthermore, the difficulty of procuring perfectly solid
and reliable roadbeds in many places is often overcome by the use of
this system.

In making a telfo