Mi"cro*mere (?), n. [Micro- + -mere.] (Biol.) One of the smaller cells,
or blastomeres, resulting from the complete segmentation of a
telolecithal ovum.
Mi*crom"e*ter (?), n. [Micro- + -meter: cf. F. micromètre.] An
instrument, used with a telescope or microscope, for measuring minute
distances, or the apparent diameters of objects which subtend minute
angles. The measurement given directly is that of the image of the
object formed at the focus of the object glass.
Circular, or Ring, micrometer, a metallic ring fixed in the focus of
the object glass of a telescope, and used to determine differences of
right ascension and declination between stars by observations of the
times at which the stars cross the inner or outer periphery of the
ring. -- Double image micrometer, a micrometer in which two images of
an object are formed in the field, usually by the two halves of a
bisected lens which are movable along their line of section by a screw,
and distances are determined by the number of screw revolutions
necessary to bring the points to be measured into optical coincidence.
When the two images are formed by a bisected object glass, it is called
a divided-object-glass micrometer, and when the instrument is large and
equatorially mounted, it is known as a heliometer. -- Double refraction
micrometer, a species of double image micrometer, in which the two
images are formed by the double refraction of rock crystal. -- Filar,
or Bifilar, micrometer. See under Bifilar. -- Micrometer caliper or
gauge (Mech.), a caliper or gauge with a micrometer screw, for
measuring dimensions with great accuracy. -- Micrometer head, the head
of a micrometer screw. -- Micrometer microscope, a compound microscope
combined with a filar micrometer, used chiefly for reading and
subdividing the divisions of large astronomical and geodetical
instruments. -- Micrometer screw, a screw with a graduated head used in
some forms of micrometers. -- Position micrometer. See under Position.
-- Scale, or Linear, micrometer, a minute and very delicately graduated
scale of equal parts used in the field of a telescope or microscope,
for measuring distances by direct comparison.
{ Mi`cro*met"ric (?), Mi`cro*met"ric*al (?), } a. [Cf. F.
micrométrique.] Belonging to micrometry; made by the micrometer. --
Mi`cro*met"ric*al*ly, adv.
Mi*crom"e*try (?), n. The art of measuring with a micrometer.
Mi`cro*mil"li*me`ter (?), n. [Micro- + millimeter.] The millionth part
of a meter.
Mic"ron (?), n. [NL., fr. Gr. mikro`s small.] (Physics) A measure of
length; the thousandth part of one millimeter; the millionth part of a
meter.
Mi"cro*ne"sian (?), a. [From Micronesia, fr. Gr. mikro`s small + nh^sos
an island.] Of or pertaining to Micronesia, a collective designation of
the islands in the western part of the Pacific Ocean, embracing the
Marshall and Gilbert groups, the Ladrones, the Carolines, etc.
Mi`cro*ne"sians (?), n. pl.; sing. Micronesian. (Ethnol.) A dark race
inhabiting the Micronesian Islands. They are supposed to be a mixed
race, derived from Polynesians and Papuans.
Mi`cro*nom"e*ter (?), n. [Micro- + chronometer.] An instrument for
noting minute portions of time.
Mi`cro*ör"gan*ism (?), n. [Micro- + organism.] (Biol.) Any microscopic
form of life; -- particularly applied to bacteria and similar
organisms, esp. such are supposed to cause infectious diseases.
Mi`cro*pan"to*graph (?), n. [Micro- + pantograph.] A kind of
pantograph which produces copies microscopically minute.
Mi`cro*peg"ma*tite (?), n. [Micro- + pegmatite.] (Min.) A rock showing
under the microscope the structure of a graphic granite (pegmatite). --
Mi`cro*peg`ma*tit"ic (#), a.
Mi"cro*phone (?), n. [Micro- + Gr. &?; sound, voice: cf. F.
microphone.] (Physics) An instrument for intensifying and making
audible very feeble sounds. It produces its effects by the changes of
intensity in an electric current, occasioned by the variations in the
contact resistance of conducting bodies, especially of imperfect
conductors, under the action of acoustic vibrations.
Mi`cro*phon"ics (?), n. [See Microphone.] The science which treats of
the means of increasing the intensity of low or weak sounds, or of the
microphone.
Mi*croph"o*nous (?), a. Serving to augment the intensity of weak
sounds; microcoustic.