BRICK ROADS. 15 
The proper thickness for the bedding depends, of course, upon the 
extent of the inequalities in the brick and the foundation. In the 
past, 2 inches has been the most usual thickness, but as the accuracy 
secured in constructing the base has increased, and as the size of 
paving brick has become more nearly uniform, the necessary thick- 
ness for the bedding has naturally diminished. At present a thick- 
ness of 1-J inches is considered conservative where the bedding con- 
sists of sand alone, but where dry mortar is employed the inequalities 
should be so reduced that a thickness of 1 inch will be sufficient, 
because it is cheaper to make the surface of the base uniform than 
to supply the additional dry mortar which would otherwise be 
required. 
Sand bedding should consist of moderately clean sand and be free 
from pebbles. If dirt or vegetable matter is present, it will soon be 
leached out and cause unevenness to develop in the pavement, while 
pebbles prevent the brick from securing a uniform bearing and ulti- 
mately produce the same result. It is also important that the sand 
should be dry when spread, especially if it is fine, because a compara- 
tively small amount of moisture increases the volume of fine sand 
considerably, and moisture when present is not, as a rule, uniformly 
distributed. Even if it were uniformly distributed at the start, some 
spots would dry out more rapidly than others while the spreading 
was under way, and a lack of uniformity would thus be produced in 
the bedding. 
In forming the bedding the sand is uniformly spread over the base 
to a depth slightly in excess of that desired, and is then smoothed off 
by drawing over it a template shaped to conform with the cross sec- 
tion of the finished pavement. The length of the template is ordi- 
narily made equal to the width of the pavement where this is less 
than about 25 feet, and equal to half the width for wider pavements. 
Timber guides may be laid in the same direction as the pavement for 
the template to slide on, or the curbs may be made to serve as guides 
where this is convenient. 
After the bedding material is spread and unif ormly " struck off " 
with the template to a depth slightly in excess of that required, it 
should be thoroughly compacted by rolling with a hand roller weigh- 
ing from 300 to 400 pounds, and any depressions which form should 
be corrected. This is necessary in order to secure uniform density 
and to prevent unequal settlement of the surface. 
If a dry mortar bedding is to be employed, the sand used should be 
clean and the manner of spreading and compacting the bedding 
should be practically the same as for sand alone. The proportion in 
which the sand and cement should be mixed is a subject regarding 
which there is more or less uncertainty at present. One part of 
