What is "mine dial"

Mine \Mine\, n. [F., fr. LL. mina. See Mine, v. i.]

1. A subterranean cavity or passage; especially:

   1. A pit or excavation in the earth, from which metallic ores, precious stones, coal, or other mineral substances are taken by digging; -- distinguished from the pits from which stones for architectural purposes are taken, and which are called quarries.

   2. (Mil.) A cavity or tunnel made under a fortification or other work, for the purpose of blowing up the superstructure with some explosive agent.

2. Any place where ore, metals, or precious stones are got by digging or washing the soil; as, a placer mine.

3. (Fig.): A rich source of wealth or other good.
   --Shak.

4. (Mil.) An explosive device placed concealed in a location, on land or at sea, where an enemy vehicle or enemy personnel may pass through, having a triggering mechanism which detects people or vehicles, and which will explode and kill or maim personnel or destroy or damage vehicles. A mine placed at sea (formerly called a torpedo, see torpedo[2]

   1. ) is also called an marine mine and underwater mine and sometimes called a floating mine, even though it may be anchored to the floor of the sea and not actually float freely. A mine placed on land (formerly called a torpedo, see torpedo[3]), usually buried, is called a land mine.

      Mine dial, a form of magnetic compass used by miners.

      Mine pig, pig iron made wholly from ore; in distinction from cinder pig, which is made from ore mixed with forge or mill cinder.

      gold mine (a) a mine where gold is obtained.

   2. (Fig.) a rich source of wealth or other good; same as Mine 3.
      --Raymond.