more pieces of rock. Field and
river stone offer an additional advantage in that they are quickly
handled, are generally of convenient size, and are more readily broken
either by hand or by machine than most varieties of rock which are
quarried in the usual way.

"It is a simple task to break stone for macadam roadways, and by the aid
of modern inventions it can be done cheaply and quickly. Hand-broken
stone is fairly out of date and is rarely used in America where any
considerable amount of work is to be undertaken. Stone may be broken by
hand at different points along the roadside where repairs are needed
from time to time, but the extra cost of production by this method
forbids its being carried on where extended work is undertaken.
Hand-broken stone is generally more uniform in size, more nearly cubical
in shape, and has sharper angles than that broken by machinery, but the
latter, when properly assorted or screened, has been found to meet every
requirement.

"A good crusher driven by eight horsepower will turn out from forty to
eighty cubic yards of two-inch stone per day of ten hours, and will cost
from four hundred dollars upward, according to quality.

"Some crushers are made either stationary, semistationary, or portable,
according to the needs of the purchaser, and for country-road work it is
sometimes very desirable to have a portable crusher to facilitate its
easy transfer from one part of the township to another. The same
portable engine that is used in thrashing, sawing wood, and other
operations requiring the use of steam power may be used in running a
stone crusher, but it is best to remember that a crusher will do its
best and most economical work when run by a machine having a horsepower
somewhat in excess of the power actually required.

"As the stone comes from the breaker the pieces will be found to show a
considerable variety in size, and by many practical road-makers it is
regarded as best that these sizes should be assorted and separated,
since each has its particular use. To do this work by hand would be
troublesome and expensive, and screens are generally employed for that
purpose. Screens are not absolutely necessary, and many road-makers do
not use them; but they insure uniformity in size of pieces, and
uniformity means in many cases superior wear, smoothness, and economy.
Most of the screens in common use today are of the rotary kind. In
operating they are generally so arranged that the