376 LAWS OF MARYLAND.

Nothing in this chapter shall be taken to prohibit a gas or
an electrical corporation from establishing a sliding scale for
the automatic adjustment of charges for gas, electricity or any
service rendered, or to be rendered, and the dividends to be
paid to stockholders of such gas corporations or electrical cor-
poration, provided that the sliding scale shall have been filed
with the proper Commission; but nothing in this subdivision
shall operate to prevent the Commission from fixing proper,
just and reasonable rates and charges to be made for service,
as authorized in this article.

SEC. 31 3/4. The Commission shall have the general supervi-
sion of all persons and gas corporations and electrical corpo-
rations having authority under any general or special law,
or under any charter or franchise, to lay down, erect or main-
tain wires, pipes, conduits, ducts or other fixtures in, over or
under the streets, highways and public places of any munici-
pality, for the purpose of furnishing or distributing gas, both
natural and artificial, or of furnishing or transmitting elec-
tricity for light, heat or power, or maintaining underground
conduits or ducts for electrical conductors.

Investigate and ascertain, from time to time, the quality of
gas supplied by persons and corporations, examine the meth-
ods employed by such persons, corporations, in manufacturing,
selling, delivering or supplying gas or electricity for light, heat
or power, and in transmitting the same, and have power to
order such improvements as will best promote the public in-
terest, preserve the public health and protect those using such
gas or electricity and those employed in the manufacture and
distribution thereof, or in the maintenance and operation of
the works, wires, poles, lines, conduits, ducts and systems in
connection therewith.

Have power by order to fix the standard illuminating power
and purity of gas, not less than that prescribed by law, both
natural gas and gas to be manufactured, distributed or sold
by persons, corporations, for lighting, heating or power pur-
poses, and to prescribe methods of regulation of the, electric
supply system as to the use for incandescent lighting, and fix
the initial efficiency of incandescent lamps furnished by the
persons, corporations, generating and selling electric current
for lighting, and by order to require the gas so manufactured,
distributed or sold to equal the standard so fixed by it, and to
establish regulations as to pressure at which gas shall be de-
livered. For the purpose of determining whether the gas man-
ufactured, distributed or sold by such persons or corporations
for lighting, heating or power purposes conforms to the stand-
ard of illuminating power and purity, and, of its own motion,