ms of Martin Frobisher's outfit, we find, "For a
greate Mappe Universall of Mercator, in prente, L1, 6_s._ 8_d._"

MERCATOR'S SAILING. Performed loxodromically, by means of Mercator's
charts.

MERCHANTMAN. A trading vessel employed in importing and exporting goods
to and from any quarter of the globe.

MERCHANT SERVICE. The mercantile marine.

MERCHANT-VENTURERS. A company of merchants who traded with Russia,
Turkey, and other distant parts. In the _Affectionate Shepheard_, 1594,
we find--

"Well is he tearm'd a merchant venturer,
Since he doth venter lands, and goods, and all;
When he doth travell for his traffique far,
Little he knowes what fortune may befall."

MERCURIAL GAUGE. A curved tube partly filled with mercury, to show the
pressure of steam in an engine.

MERCURY. One of the ancient inferior planets, and the nearest to the
sun, as far as we yet know. (_See_ TRANSIT OF.) Also, a name for
quicksilver; the fluid metal so useful in the construction of the marine
barometer, thermometer, and artificial horizon.

MERE. An Anglo-Saxon word still in use, sometimes meaning a lake, and
generally the sea itself.

MERIDIAN, OF THE EARTH. Is an imaginary great circle passing through the
zenith and the poles, and cutting the equator at right angles. When the
sun is on the meridian of any place, it is mid-day there, and at all
places situated under the same meridian.--_First meridian_ is that from
which the longitude is reckoned. Magnetic meridian is not a great circle
but a wavy line uniting those poles. In common acceptation, a meridian
is any line supposed to be drawn from the north to the south pole;
therefore a place being under the same meridian as another place, is
either due north or south of it.--_Plane of the meridian_ is the plane
of this great circle, and its intersection with the sensible horizon is
called the _meridian line_.--The _meridian transit_ of a heavenly body
is the act of passing over the said plane, when it is either due north
or south of the spectator.--_Ante meridiem_, or A.M., before
noon.--_Post meridiem_, or P.M., after noon.

MERIDIAN ERROR. The deviation of a transit-instrument from the plane of
the meridian at the horizon; it is also termed the _azimuthal error_.

MERLON. That part of the parapet of a battery between two adjacent
embrasures, 15 or 20 feet long in general.

MERMAID. A fabulous sea-creature of which the upper half was said to
resemble a woman