NAUTICAL  DICTIONARY.                              [HAI

NADIR (Fr. Nadir), in astronomy, is that point in the heavens
immediately under any place on the globe.    See Zenith.

NAILS. Of the various descriptions of nails used for ship¬
building purposes, we may notice the following :—

Clamp-nails, are short stout nails with large heads for fasten¬
ing iron clamps or plates.

Composition-nails, which are made of a mixed metal known by
the name of composition, are used for various purposes, particu¬
larly for nailing on copper-sheathing, whence they often incor¬
rectly get the name of copper nails. They are also sometimes
made of a large size to be used for decks, or for the butt ends of
small vessels ; for which latter purpose, however, bolts are pre¬
ferable. Those used for wood-sheathing are of an intermediate
size.

Copper-nails, are chiefly used in boatbuilding and for nailing
in any splinters that may occur in a vessel's bottom-plank during
the process of building; also for nailing up the binnacle, for
which purpose they are preferable to iron nails, because they have
no effect on the magnetic needle.    See Composition nails.

NAILS (DECK).    See Nails (Spike and Composition).

Flat-nails, are small sharp-pointed nails, with flat thin heads,
for nailing the scarphs of moulds, &c.

Ribband-nails, have large round heads, so that they may be
the more easily drawn, &c.; they are used chiefly for fastening
ribbands, or for nailing any cleat which requires to be taken off
again.

Rudder-nails, are similar to clamp-nails, but used mostly for
fastening the pintles and braces of the rudder, which, however,
are now more commonly fastened by copper or iron bolts: the most
of these bolts should go right through and be clinched.

Scupper-nails, are short nails with very broad flat heads;
they are used for nailing down pieces of leather under the
scuppers to carry off water while washing the decks, for nailing
down tarpaulings, and for other purposes.

Sheathing-nails. Nails used for fastening copper, yellow-
metal, or wood-sheathing, on a vessel's bottom, he. Those used
for wood-sheathing are either of iron or composition. For copper
or yellow metal sheathing, composition nails are employed.

Spike-nails, or Spikes. A name for nails of four inches and
upwards in length,    -^^^y   ^^^'^-'^    >                   ,    -;     ^

Deck-nails, are a kind of spike, with larger heads, commonly

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