DICTIONARY OF

Isohyet 183 Ivory's Rule
Isohyet. Line, on meteorological chart, passing through all places having the same amount
of rainfall.
Isoneph. Line, on a meteorological chart, passing through all positions having the same
amount of cloud.
Isotherm. Line, on a meteorological chart, passing through all positions having the same
temperature.
Isothermal Expansion. Expansion of gas, or steam, without an accompanying reduction of
temperature. This necessitates an intake of heat during expansion.
Isothermal Line. An isotherm.
I.T.B. Integrated Tug Barge. A barge pushed by a tug joined to it.
Ivory's Rule. Method of solving the 'latitude of double altitude problem; the PZX triangle
being divided into right-angled spherical triangles;