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4 definitions found
From The Collaborative International Dictionary of English v.0.44 : [ gcide ]
Percussion \Per*cus"sion\, n. [L. percussio: cf. F. percussion.
See Percuss.]
1. The act of percussing, or striking one body against
another; forcible collision, esp. such as gives a sound or
report. --Sir I. Newton.
[1913 Webster]
2. Hence: The effect of violent collision; vibratory shock;
impression of sound on the ear.
[1913 Webster]
The thunderlike percussion of thy sounds. --Shak.
[1913 Webster]
3. (Med.) The act of tapping or striking the surface of the
body in order to learn the condition of the parts beneath
by the sound emitted or the sensation imparted to the
fingers. Percussion is said to be immediate if the blow is
directly upon the body; if some interventing substance, as
a pleximeter, is, used, it is called mediate.
[1913 Webster]
Center of percussion. See under Center.
Percussion bullet, a bullet containing a substance which is
exploded by percussion; an explosive bullet.
Percussion cap, a small copper cap or cup, containing
fulminating powder, and used with a percussion lock to
explode gunpowder.
Percussion fuze. See under Fuze.
Percussion lock, the lock of a gun that is fired by
percussion upon fulminating powder.
Percussion match, a match which ignites by percussion.
Percussion powder, powder so composed as to ignite by
slight percussion; fulminating powder.
Percussion sieve, Percussion table, a machine for sorting
ores by agitation in running water.
[1913 Webster]
From The Collaborative International Dictionary of English v.0.44 : [ gcide ]
Center \Cen"ter\, n. [F. centre, fr. L. centrum, fr. round which
a circle is described, fr. ? to prick, goad.]
1. A point equally distant from the extremities of a line,
figure, or body, or from all parts of the circumference of
a circle; the middle point or place.
[1913 Webster]
2. The middle or central portion of anything.
[1913 Webster]
3. A principal or important point of concentration; the
nucleus around which things are gathered or to which they
tend; an object of attention, action, or force; as, a
center of attaction.
[1913 Webster]
4. The earth. [Obs.] --Shak.
[1913 Webster]
5. Those members of a legislative assembly (as in France) who
support the existing government. They sit in the middle of
the legislative chamber, opposite the presiding officer,
between the conservatives or monarchists, who sit on the
right of the speaker, and the radicals or advanced
republicans who occupy the seats on his left, See Right,
and Left.
[1913 Webster]
6. (Arch.) A temporary structure upon which the materials of
a vault or arch are supported in position until the work
becomes self-supporting.
[1913 Webster]
7. (Mech.)
(a) One of the two conical steel pins, in a lathe, etc.,
upon which the work is held, and about which it
revolves.
(b) A conical recess, or indentation, in the end of a
shaft or other work, to receive the point of a center,
on which the work can turn, as in a lathe.
[1913 Webster]
Note: In a lathe the
live center is in the spindle of the head stock; the
dead center is on the tail stock.
Planer centers are stocks carrying centers, when the object
to be planed must be turned on its axis.
[1913 Webster]
Center of an army, the body or troops occupying the place
in the line between the wings.
Center of a curve or Center of a surface (Geom.)
(a) A point such that every line drawn through the point
and terminated by the curve or surface is bisected at
the point.
(b) The fixed point of reference in polar co["o]rdinates.
See Co["o]rdinates.
Center of curvature of a curve (Geom.), the center of that
circle which has at any given point of the curve closer
contact with the curve than has any other circle whatever.
See Circle.
Center of a fleet, the division or column between the van
and rear, or between the weather division and the lee.
Center of gravity (Mech.), that point of a body about which
all its parts can be balanced, or which being supported,
the whole body will remain at rest, though acted upon by
gravity.
Center of gyration (Mech.), that point in a rotating body
at which the whole mass might be concentrated
(theoretically) without altering the resistance of the
intertia of the body to angular acceleration or
retardation.
Center of inertia (Mech.), the center of gravity of a body
or system of bodies.
Center of motion, the point which remains at rest, while
all the other parts of a body move round it.
Center of oscillation, the point at which, if the whole
matter of a suspended body were collected, the time of
oscillation would be the same as it is in the actual form
and state of the body.
Center of percussion, that point in a body moving about a
fixed axis at which it may strike an obstacle without
communicating a shock to the axis.
Center of pressure (Hydros.), that point in a surface
pressed by a fluid, at which, if a force equal to the
whole pressure and in the same line be applied in a
contrary direction, it will balance or counteract the
whole pressure of the fluid.
[1913 Webster]
From Webster's Revised Unabridged Dictionary (1913) : [ web1913 ]
Percussion \Per*cus"sion\, n. [L. percussio: cf. F. percussion.
See Percuss.]
1. The act of percussing, or striking one body against
another; forcible collision, esp. such as gives a sound or
report. --Sir I. Newton.
2. Hence: The effect of violent collision; vibratory shock;
impression of sound on the ear.
The thunderlike percussion of thy sounds. --Shak.
3. (Med.) The act of tapping or striking the surface of the
body in order to learn the condition of the parts beneath
by the sound emitted or the sensation imparted to the
fingers. Percussion is said to be immediate if the blow is
directly upon the body; if some interventing substance, as
a pleximeter, is, used, it is called mediate.
Center of percussion. See under Center.
Percussion bullet, a bullet containing a substance which is
exploded by percussion; an explosive bullet.
Percussion cap, a small copper cap or cup, containing
fulminating powder, and used with a percussion lock to
explode gunpowder.
Percussion fuze. See under Fuze.
Percussion lock, the lock of a gun that is fired by
percussion upon fulminating powder.
Percussion match, a match which ignites by percussion.
Percussion powder, powder so composed as to ignite by
slight percussion; fulminating powder.
Percussion sieve, Percussion table, a machine for sorting
ores by agitation in running water.
From Webster's Revised Unabridged Dictionary (1913) : [ web1913 ]
Center \Cen"ter\, n. [F. centre, fr. L. centrum, fr. round which
a circle is described, fr. ? to prick, goad.]
1. A point equally distant from the extremities of a line,
figure, or body, or from all parts of the circumference of
a circle; the middle point or place.
2. The middle or central portion of anything.
3. A principal or important point of concentration; the
nucleus around which things are gathered or to which they
tend; an object of attention, action, or force; as, a
center of attaction.
4. The earth. [Obs.] --Shak.
5. Those members of a legislative assembly (as in France) who
support the existing government. They sit in the middle of
the legislative chamber, opposite the presiding officer,
between the conservatives or monarchists, who sit on the
right of the speaker, and the radicals or advanced
republicans who occupy the seats on his left, See Right,
and Left.
6. (Arch.) A temporary structure upon which the materials of
a vault or arch are supported in position until the work
becomes self-supporting.
7. (Mech.)
(a) One of the two conical steel pins, in a lathe, etc.,
upon which the work is held, and about which it
revolves.
(b) A conical recess, or indentation, in the end of a
shaft or other work, to receive the point of a center,
on which the work can turn, as in a lathe.
Note: In a lathe the
live center is in the spindle of the head stock; the
dead center is on the tail stock.
Planer centers are stocks carrying centers, when the object
to be planed must be turned on its axis.
Center of an army, the body or troops occupying the place
in the line between the wings.
Center of a curve or surface (Geom.)
(a) A point such that every line drawn through the point
and terminated by the curve or surface is bisected at
the point.
(b) The fixed point of reference in polar co["o]rdinates.
See Co["o]rdinates.
Center of curvature of a curve (Geom.), the center of that
circle which has at any given point of the curve closer
contact with the curve than has any other circle whatever.
See Circle.
Center of a fleet, the division or column between the van
and rear, or between the weather division and the lee.
Center of gravity (Mech.), that point of a body about which
all its parts can be balanced, or which being supported,
the whole body will remain at rest, though acted upon by
gravity.
Center of gyration (Mech.), that point in a rotating body
at which the whole mass might be concentrated
(theoretically) without altering the resistance of the
intertia of the body to angular acceleration or
retardation.
Center of inertia (Mech.), the center of gravity of a body
or system of bodies.
Center of motion, the point which remains at rest, while
all the other parts of a body move round it.
Center of oscillation, the point at which, if the whole
matter of a suspended body were collected, the time of
oscillation would be the same as it is in the actual form
and state of the body.
Center of percussion, that point in a body moving about a
fixed axis at which it may strike an obstacle without
communicating a shock to the axis.
Center of pressure (Hydros.), that point in a surface
pressed by a fluid, at which, if a force equal to the
whole pressure and in the same line be applied in a
contrary direction, it will balance or counteract the
whole pressure of the fluid.
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