Found 1 items, similar to Micrometer screw.
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Definition: Micrometer screw
(skr[udd]), n. [OE. scrue, OF. escroue, escroe,
female screw, F. ['e]crou, L. scrobis a ditch, trench, in
LL., the hole made by swine in rooting; cf. D. schroef a
screw, G. schraube, Icel. skr[=u]fa.]
1. A cylinder, or a cylindrical perforation, having a
continuous rib, called the thread, winding round it
spirally at a constant inclination, so as to leave a
continuous spiral groove between one turn and the next, --
used chiefly for producing, when revolved, motion or
pressure in the direction of its axis, by the sliding of
the threads of the cylinder in the grooves between the
threads of the perforation adapted to it, the former being
distinguished as the external, or male screw, or, more
usually the screw; the latter as the internal, or female
screw, or, more usually, the nut.
Note: The screw, as a mechanical power, is a modification of
the inclined plane, and may be regarded as a
right-angled triangle wrapped round a cylinder, the
hypotenuse of the marking the spiral thread of the
screw, its base equaling the circumference of the
cylinder, and its height the pitch of the thread.
2. Specifically, a kind of nail with a spiral thread and a
head with a nick to receive the end of the screw-driver.
Screws are much used to hold together pieces of wood or to
fasten something; -- called also wood screws
, and screw nails
. See also Screw bolt
3. Anything shaped or acting like a screw; esp., a form of
wheel for propelling steam vessels. It is placed at the
stern, and furnished with blades having helicoidal
surfaces to act against the water in the manner of a
screw. See Screw propeller
4. A steam vesel propelled by a screw instead of wheels; a
screw steamer; a propeller.
5. An extortioner; a sharp bargainer; a skinflint; a niggard.
6. An instructor who examines with great or unnecessary
severity; also, a searching or strict examination of a
student by an instructor. [Cant, American Colleges]
7. A small packet of tobacco. [Slang] --Mayhew.
8. An unsound or worn-out horse, useful as a hack, and
commonly of good appearance. --Ld. Lytton.
9. (Math.) A straight line in space with which a definite
linear magnitude termed the pitch is associated (cf. 5th
(b) ). It is used to express the displacement of a rigid
body, which may always be made to consist of a
rotation about an axis combined with a translation
parallel to that axis.
10. (Zo["o]l.) An amphipod crustacean; as, the skeleton screw
). See Sand screw
, under Sand
, Compound screw
, Foot screw
, etc. See
A screw loose
, something out of order, so that work is not
done smoothly; as, there is a screw loose somewhere. --H.
, or perpetual screw
, a screw used to give
motion to a toothed wheel by the action of its threads
between the teeth of the wheel; -- called also a worm
. See under Lag
, a screw with fine threads, used for the
measurement of very small spaces.
Right and left screw
, a screw having threads upon the
opposite ends which wind in opposite directions.
. See Shaft alley
, under Shaft
(a) The curious spirally coiled pod of a leguminous tree
) growing from Texas to
California. It is used for fodder, and ground into
meal by the Indians.
(b) The tree itself. Its heavy hard wood is used for
fuel, for fencing, and for railroad ties.
, a bolt having a screw thread on its shank, in
distinction from a key bolt
. See 1st Bolt
, a device, resembling a die, for cutting the
thread on a wooden screw.
. See under Dock
, a marine engine for driving a screw
. See Spiral gear
, under Spiral
. Same as Jackscrew
, a wrench for turning a screw or nut; a spanner
(a) One of a series of machines employed in the
manufacture of wood screws.
(b) A machine tool resembling a lathe, having a number of
cutting tools that can be caused to act on the work
successively, for making screws and other turned
pieces from metal rods.
(Bot.), any plant of the endogenous genus
, of which there are about fifty species,
natives of tropical lands from Africa to Polynesia; --
named from the spiral arrangement of the pineapple-like
, a device for cutting threads on small screws,
consisting of a thin steel plate having a series of
perforations with internal screws forming dies.
, a press in which pressure is exerted by means
of a screw.
, a screw or spiral bladed wheel, used in
the propulsion of steam vessels; also, a steam vessel
propelled by a screw.
(Zo["o]l.), a long, slender, spiral gastropod
shell, especially of the genus Turritella and allied
genera. See Turritella
, a steamship propelled by a screw.
, the spiral rib which forms a screw.
(Paleon.), the fossil stem of an encrinite.
(Bot.), any plant of the genus Helicteres
consisting of about thirty species of tropical shrubs,
with simple leaves and spirally twisted, five-celled
capsules; -- also called twisted-horn
, and twisty
, a stop valve which is opened or closed by a
(Zo["o]l.), the larva of an American fly
), allied to the blowflies, which
sometimes deposits its eggs in the nostrils, or about
wounds, in man and other animals, with fatal results.
(a) A wrench for turning a screw.
(b) A wrench with an adjustable jaw that is moved by a
To put the screws on
or To put the screw on
, to use
pressure upon, as for the purpose of extortion; to coerce.
To put under the screw
or To put under the screws
subject to pressure; to force.
, a metal screw with a sharp thread of coarse
pitch, adapted to holding fast in wood. See Illust. of
, under Wood
, n. [Micro- + -meter: cf. F.
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.
, 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
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.
, or Bifilar micrometer
. See under
or Micrometer gauge
(Mech.), a caliper
or gauge with a micrometer screw, for measuring dimensions
with great accuracy.
, the head of a micrometer screw.
, a compound microscope combined with
a filar micrometer, used chiefly for reading and
subdividing the divisions of large astronomical and
, a screw with a graduated head used in
some forms of micrometers; turning the head one full
revolution advances the position of the tip of the screw
only by a little.
. See under Position
, 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.