What is "to arm the lead"

Lead \Lead\ (l[e^]d), n. [OE. led, leed, lead, AS. le['a]d; akin to D. lood, MHG. l[=o]t, G. loth plummet, sounding lead, small weight, Sw. & Dan. lod. [root]123.]

1. (Chem.) One of the elements, a heavy, pliable, inelastic metal, having a bright, bluish color, but easily tarnished. It is both malleable and ductile, though with little tenacity, and is used for tubes, sheets, bullets, etc. Its specific gravity is 11.37. It is easily fusible (melting point 327.5[deg] C), forms alloys with other metals, and is an ingredient of solder and type metal. Atomic number 8

2. Atomic weight, 207.2. Symbol Pb (L. Plumbum). It is chiefly obtained from the mineral galena, lead sulphide. 2. An article made of lead or an alloy of lead; as:

   1. A plummet or mass of lead, used in sounding at sea.

   2. (Print.) A thin strip of type metal, used to separate lines of type in printing.

   3. Sheets or plates of lead used as a covering for roofs; hence, pl., a roof covered with lead sheets or terne plates.

      I would have the tower two stories, and goodly leads upon the top.
      --Bacon

3. A small cylinder of black lead or graphite, used in pencils. Black lead, graphite or plumbago; -- so called from its leadlike appearance and streak. [Colloq.] Coasting lead, a sounding lead intermediate in weight between a hand lead and deep-sea lead. Deep-sea lead, the heaviest of sounding leads, used in water exceeding a hundred fathoms in depth. --Ham. Nav. Encyc. Hand lead, a small lead use for sounding in shallow water. Krems lead, Kremnitz lead [so called from Krems or Kremnitz, in Austria], a pure variety of white lead, formed into tablets, and called also Krems white, or Kremnitz white, and Vienna white. Lead arming, tallow put in the hollow of a sounding lead. See To arm the lead (below). Lead colic. See under Colic. Lead color, a deep bluish gray color, like tarnished lead. Lead glance. (Min.) Same as Galena. Lead line

   1. (Med.) A dark line along the gums produced by a deposit of metallic lead, due to lead poisoning.

   2. (Naut.) A sounding line. Lead mill, a leaden polishing wheel, used by lapidaries. Lead ocher (Min.), a massive sulphur-yellow oxide of lead. Same as Massicot. Lead pencil, a pencil of which the marking material is graphite (black lead). Lead plant (Bot.), a low leguminous plant, genus Amorpha ( Amorpha canescens), found in the Northwestern United States, where its presence is supposed to indicate lead ore. --Gray. Lead tree.

      1. (Bot.) A West Indian name for the tropical, leguminous tree, Leuc[ae]na glauca; -- probably so called from the glaucous color of the foliage.

      2. (Chem.) Lead crystallized in arborescent forms from a solution of some lead salt, as by suspending a strip of zinc in lead acetate.

         Mock lead, a miner's term for blende.

         Red lead, a scarlet, crystalline, granular powder, consisting of minium when pure, but commonly containing several of the oxides of lead. It is used as a paint or cement and also as an ingredient of flint glass.

         Red lead ore (Min.), crocoite.

         Sugar of lead, acetate of lead.

         To arm the lead, to fill the hollow in the bottom of a sounding lead with tallow in order to discover the nature of the bottom by the substances adhering.
         --Ham. Nav. Encyc.

         To cast the lead, or To heave the lead, to cast the sounding lead for ascertaining the depth of water.

         White lead, hydrated carbonate of lead, obtained as a white, amorphous powder, and much used as an ingredient of white paint.