Fig. 237. MALAPTERURUS.
Man-hole.
The cistern-like depression in the ground for giving access to the ends
of tubes in electric conduits. (See Conduit, Electric Subway.)
Marked End or Pole.
The north pole or north seeking pole of a magnet, so called because it
is usually marked with a notch or scratch by the maker. The south pole
is called the unmarked end.
Mass.
The quantity of matter in a body. The C. G. S. unit of mass is the
quantity of matter in a gram. While weight varies with latitude and
other circumstances, mass is invariable.
The unit of mass is also defined as the quantity of matter which in a
balance will counterpoise a standard mass, the gram or pound. As the
gram is intended to be the mass of one cubic centimeter of water at
3.09º C. (39º F.), the C. G. S. unit of mass is really 1.000013 gram.
As a primary unit its dimensions are indicated by M.
Mass, Electric.
A term for quantity of electricity. The unit mass is such a quantity as
at unit distance will act with unit force.
Matter, Electric.
The imaginary substance constituting electricity; a conception used
purely as a matter of convenience.
[Transcriber's note: The electron was discovered five years after this
publication.]
Matter, Radiant.
Matter in the ultra-gaseous or so-called fourth state. In the gaseous
state the molecules of a gas are in perpetual kinetic motion, colliding
actually or virtually with each other, rebounding from such approach,
and striking also the walls of the containing vessel. But except for
these deflections, which are of enormous frequency, the paths of the
molecules would be perfectly straight.
In the radiant state matter exists in so high a vacuum that collisions
of the molecules rarely occur, and the molecules simply beat back and
forth in straight lines from side to side of the containing vessel.
A layer of gas in this condition is termed a Crookes' layer, from Prof.
William Crookes, who discovered and investigated these phenomena.