Fig. 3. ELECTRO-MAGNETIC CAR WHEEL.
Fig. 4. ELECTRO-MAGNETIC FRICTION GEAR.
Admiralty Rule of Heating.
The British Admiralty specifications for the permissible heating of
dynamos. It holds that at the end of a run of six hours no part of the
dynamo under trial shall show a rise of temperature greater than 11º C.
(20º F.) above the temperature of the air surrounding it. This is
thought to be a very stringent and unnecessarily high requirement.
Aerial Conductor.
An electric conductor carried from housetops, poles, or otherwise so as
to be suspended in the air, as distinguished from an underground or
submarine conductor.
Affinity.
The attraction of atoms and in some cases perhaps of molecules for each
other by the force of chemical attraction. When the affinity is allowed
to act or is carried out, a chemical change, as distinguished from a
physical or mechanical change, ensues. Thus if sulphur and iron are each
finely powdered and are mixed the change and mixture are mechanical. If
slightly heated the sulphur will melt, which is a physical change. If
heated to redness the iron will combine with the sulphur forming a new
substance, ferric sulphide, of new properties, and especially
characterized by unvarying and invariable ratios of sulphur to iron.
Such change is a chemical one, is due to chemical affinity, is due to a
combination of the atoms, and the product is a chemical compound.
13 STANDARD ELECTRICAL DICTIONARY.
Agir Motor.
The Anderson and Girdlestone motor. The term "agir" is made up from the
first portions of each name.
Agonic Line.
The locus of points on the earth's surface where the magnetic needle
points to the true north; an imaginary line determined by connecting
points on the earth's surface where the needle lies in the true
geographical meridian. Such a line at present, starting from the north
pole goes through the west of Hudson's Bay, leaves the east coast of
America near Philadelphia, passes along the eastern West Indies, cuts
off the eastern projection of Brazil and goes through the South Atlantic
to the south pole. Thence it passes through the west of Australia, the
Indian Ocean, Arabia, the Caspian sea, Russia and the White sea to the
North Pole. It crosses the equator at 70° W. and 55° E. approximately.
(See Magnetic Elements.)
Synonym--Agone.
[Transcriber's note: The file Earth_Declination_1590_1990.gif provided
by the U.S. Geological Survey (http://www.usgs.gov) is an animation of
the declination of the entire earth.]
Air.
Air is a dielectric whose specific inductive capacity at atmosphere
pressure is taken as 1. It is practically of exactly the same
composition in all places and hence can be taken as a standard. When dry
it has high resistance, between that of caoutchouc and dry paper.
Dampness increases its conductivity.
It is a mixture of oxygen and nitrogen, with a little carbonic acid gas
and other impurities. Its essential composition is:
Oxygen: (by weight) 23.14 (by volume) 21
Nitrogen: 76.86 79
The specific inductive capacity varies for different pressures thus:
Approximate
(.001 mm., .0004 inch) 0.94 (Ayrton)
Vacuum