ill, etc., more than ten
hours per day (with exceptions) but permitting overtime, not to exceed
three hours a day, on condition that it is paid at the rate of one and
one-half times the regular wage.[129] Because of the almost plenary
powers of the State and its municipal subdivisions to determine the
conditions under which work shall go forward on public projects,
statutes limiting the hours of labor on public works were also upheld at
a relatively early date.[130]

Laws Regulating Labor in Mines.--The regulation of mines being
so patently within the police power, States have been upheld in the
enactment of laws providing for appointment of mining inspectors and
requiring payment of their fees by mine owners,[131] compelling
employment of only licensed mine managers and mine examiners, and
imposing upon mine owners liability for the wilful failure of their
manager and examiner to furnish a reasonably safe place for
workmen.[132] Other similar regulations which have been sustained have
included laws requiring that entries be of a specified width,[133] that
boundary pillars be installed between adjoining coal properties as a
protection against flood in case of abandonment,[134] and that
washhouses be provided for employees.[135]

Laws Prohibiting Employment of Children in Hazardous
Occupations.--To make effective its prohibition against the
employment of persons under 16 years of age in dangerous occupations, a
State has been held to be competent to require employers at their peril
to ascertain whether their employees are in fact below that age.[136]

Laws Regulating Payment of Wages.--No unconstitutional
deprivation of liberty of contract was deemed to have been occasioned by
a statute requiring redemption in cash of store orders or other
evidences of indebtedness issued by employers in payment of wages.[137]
Nor was any constitutional defect discernible in laws requiring
railroads to pay their employees semimonthly[138] and to pay them on the
day of discharge, without abatement or reduction, any funds due
them.[139] Similarly, freedom of contract was held not to be infringed
by an act requiring that miners, whose compensation was fixed on the
basis of weight, be paid according to coal in the mine car rather than
at a certain price per ton for coal screened after it has been brought
to the surface, and conditioning such payment on the presence of no
greater percentage of dirt or impurities than that ascertained as
u