equipped with a standardized lamp will be used. The candle-power will be
determined along a line at right angles to the axis of the flame; also
along lines at angles to the axis of the flame both above and below the
horizontal. The candle-power will be read after the lamp has been
burning 20 min.

(_m_).--The time a safety lamp will continue to burn with a full charge
of illuminant will be determined.

(_n_).--Wicks in lamps must be of sufficient length to be at all times
in contact with the bottom of the vessel in which the illuminant is
contained, and, before it is used, the wick shall be dried to remove
moisture.

_Mine-Rescue Methods._--Mr. Paul, who has had perhaps as wide an
experience as any mining man in the investigation of and in rescue work
at mine disasters, is also in charge of the mine-rescue apparatus and
training for the Geological Survey. These operations consist chiefly of
a thorough test of the various artificial breathing apparatus, or
so-called oxygen helmets. Most of these are of European make and find
favor in Great Britain, Belgium, France, or Germany, largely according
as they are of domestic design and manufacture. As yet nothing has been
produced in the United States which fulfills all the requirements of a
thoroughly efficient and safe breathing apparatus for use in mine
disasters.

At the Pittsburg testing station there are a number of all kinds of
apparatus. The tests of these are to determine ease of use, of repair,
durability, safety under all conditions, period during which the supply
of artificial air or oxygen can be relied on, and other essential data.