长臂圆规

[机] 梁规

Compass \Com"pass\ (k[u^]m"pas), n. [F. compas, fr. LL.
compassus circle, prop., a stepping together; com- + passus
pace, step. See {Pace}, {Pass}.]
1. A passing round; circuit; circuitous course.

They fetched a compass of seven day's journey. --2
Kings iii. 9.

This day I breathed first; time is come round,
And where I did begin, there shall I end;
My life is run his compass. --Shak.

2. An inclosing limit; boundary; circumference; as, within
the compass of an encircling wall.

3. An inclosed space; an area; extent.

Their wisdom . . . lies in a very narrow compass.
--Addison.

4. Extent; reach; sweep; capacity; sphere; as, the compass of
his eye; the compass of imagination.

The compass of his argument. --Wordsworth.

5. Moderate bounds, limits of truth; moderation; due limits;
-- used with within.

In two hundred years before (I speak within
compass), no such commission had been executed.
--Sir J.
Davies.

6. (Mus.) The range of notes, or tones, within the capacity
of a voice or instrument.

You would sound me from my lowest note to the top of
my compass. --Shak.

7. An instrument for determining directions upon the earth's
surface by means of a magnetized bar or needle turning
freely upon a pivot and pointing in a northerly and
southerly direction.

He that first discovered the use of the compass did
more for the supplying and increase of useful
commodities than those who built workhouses.
--Locke.

8. A pair of compasses. [R.] See {Compasses.}

To fix one foot of their compass wherever they
please. --Swift.

9. A circle; a continent. [Obs.]

The tryne compas [the threefold world containing
earth, sea, and heaven. --Skeat.] --Chaucer.

{Azimuth compass}. See under {Azimuth}.

{Beam compass}. See under {Beam}.

{Compass card}, the circular card attached to the needles of
a mariner's compass, on which are marked the thirty-two
points or rhumbs.

{Compass dial}, a small pocket compass fitted with a sundial
to tell the hour of the day.

{Compass plane} (Carp.), a plane, convex in the direction of
its length on the under side, for smoothing the concave
faces of curved woodwork.

{Compass plant}, {Compass flower} (Bot.), a plant of the
American prairies ({Silphium laciniatum}), not unlike a
small sunflower; rosinweed. Its lower and root leaves are
vertical, and on the prairies are disposed to present
their edges north and south.

Its leaves are turned to the north as true as the
magnet:
This is the compass flower. --Longefellow.

{Compass saw}, a saw with a narrow blade, which will cut in a
curve; -- called also {fret saw} and {keyhole saw}.

{Compass timber} (Shipbuilding), curved or crooked timber.

{Compass window} (Arch.), a circular bay window or oriel
window.

{Mariner's compass}, a kind of compass used in navigation. It
has two or more magnetic needles permanently attached to a
card, which moves freely upon a pivot, and is read with
reference to a mark on the box representing the ship's
head. The card is divided into thirty-two points, called
also rhumbs, and the glass-covered box or bowl containing
it is suspended in gimbals within the binnacle, in order
to preserve its horizontal position.

{Surveyor's compass}, an instrument used in surveying for
measuring horizontal angles. See {Circumferentor}.

{Variation compass}, a compass of delicate construction, used
in observations on the variations of the needle.

{To fetch a compass}, to make a circuit.


Beam \Beam\ (b[=e]m), n. [AS. be['a]m beam, post, tree, ray of
light; akin to OFries. b[=a]m tree, OS. b[=o]m, D. boom, OHG.
boum, poum, G. baum, Icel. ba[eth]mr, Goth. bagms and Gr.
fy^ma a growth, fy^nai to become, to be. Cf. L. radius staff,
rod, spoke of a wheel, beam or ray, and G. strahl arrow,
spoke of a wheel, ray or beam, flash of lightning. [root]97.
See {Be}; cf. {Boom} a spar.]
1. Any large piece of timber or iron long in proportion to
its thickness, and prepared for use.

2. One of the principal horizontal timbers of a building or
ship.

The beams of a vessel are strong pieces of timber
stretching across from side to side to support the
decks. --Totten.

3. The width of a vessel; as, one vessel is said to have more
beam than another.

4. The bar of a balance, from the ends of which the scales
are suspended.

The doubtful beam long nods from side to side.
--Pope.

5. The principal stem or horn of a stag or other deer, which
bears the antlers, or branches.

6. The pole of a carriage. [Poetic] --Dryden.

7. A cylinder of wood, making part of a loom, on which
weavers wind the warp before weaving; also, the cylinder
on which the cloth is rolled, as it is woven; one being
called the fore beam, the other the back beam.

8. The straight part or shank of an anchor.

9. The main part of a plow, to which the handles and colter
are secured, and to the end of which are attached the oxen
or horses that draw it.

10. (Steam Engine) A heavy iron lever having an oscillating
motion on a central axis, one end of which is connected
with the piston rod from which it receives motion, and
the other with the crank of the wheel shaft; -- called
also {working beam} or {walking beam}.

11. A ray or collection of parallel rays emitted from the sun
or other luminous body; as, a beam of light, or of heat.

How far that little candle throws his beams!
--Shak.

12. (Fig.): A ray; a gleam; as, a beam of comfort.

Mercy with her genial beam. --Keble.

13. One of the long feathers in the wing of a hawk; -- called
also {beam feather}.

{Abaft the beam} (Naut.), in an arc of the horizon between a
line that crosses the ship at right angles, or in the
direction of her beams, and that point of the compass
toward which her stern is directed.

{Beam center} (Mach.), the fulcrum or pin on which the
working beam of an engine vibrates.

{Beam compass}, an instrument consisting of a rod or beam,
having sliding sockets that carry steel or pencil points;
-- used for drawing or describing large circles.

{Beam engine}, a steam engine having a working beam to
transmit power, in distinction from one which has its
piston rod attached directly to the crank of the wheel
shaft.

{Before the beam} (Naut.), in an arc of the horizon included
between a line that crosses the ship at right angles and
that point of the compass toward which the ship steers.

{On the beam}, in a line with the beams, or at right angles
with the keel.

{On the weather beam}, on the side of a ship which faces the
wind.

{To be on her beam ends}, to incline, as a vessel, so much on
one side that her beams approach a vertical position.