axis 
9. In ijmff. and (/rot., the central or dominat- 
ing region of a mountain-chain, or the line 
which follows the crest of a range anil thus in- 
dicates the position of the most conspicuous 
portion of the uplift, in ., folded region, or une In 
Section of iiiountain showing position of axis of synclinally 
folded sti.it. i. 
\\ lii.h the strata liavc )>een bent into anticlinals and syn- 
clinals, the axis of each Mil is tin' plane indicating the 
direction parallel to which the folding ha.s taken place, or 
toward uhich the strata incline, 
10. Iii analytical geom., any fixed line of refer- 
ence used to determine the position of a point or 
series of points (line, surface) in space. Anti- 
clinal axis, in (ml. Sec initii-ii'iiHi. - Axes of an ellip- 
soid, its maximum and minimum diameters and the diam- 
eter perpendicular to these.- Axes of coordinates, or 
Coordinate axes, in aiinliltiml ../...,;<., fixed lines on 
which 01- parallel to which an element (ahsci.ssa or urdi- 
nate) of the position of a point is measured. Axes Of 
light-elasticity, the three directions at right angles to 
one another in a biaxial crystal in which the elasticity of 
the light-ether has its maximum, minimum, and mean 
value. In a trimetriu (orthorhombic) crystal they coin- 
cide with the crystallographic axes; in a monoclimc crys- 
tal one coincides with the orthodiagonal axis, the others 
lie in the plane of symmetry. In a triclinic crystal there 
is no necessary relation between the two sets of axes. 
Axis Of a beam of light, the middle ray of the beam. 
Axis of a cone, a straight line drawn from the vertex 
to the center of the base. Axis Of a conic, a diameter 
perpendicular to the chords it bisects. Axis of a crys- 
tal, in crtixtal., one of three or four imaginary lines as- 
sumed for convenience to define the position of the 
planes of the crystal, and to exhibit its symmetry. See 
criistiiltiymiiliii. Axis of a curve, a right line dividing 
it into two symmetrical parts, so as to bisect every chord 
perpendicular to it, as in a parabola, ellipse, or hyperbola. 
Axis of a cylinder, a straight line drawn from the 
center of the one end to that of the other. Axis of 
affinity, the axis of homology of figures homological by 
affinity. Axis Of a gun or piece, the middle line of the 
lx>re of the gun. Axis of a lens, a straight line drawn 
through the optical center of the lens, and perpendicular 
to both its surfaces. Axis of a magnet, the imaginary 
line which connects the north and south poles of the 
magnet. Axis of a sphere, any straight line drawn 
through the center and terminated both ways by the sur- 
face of the sphere. Axis of a spherical, concave, or 
convex mirror, a straight line which passes through the 
geometrical and optical centers of the mirror. Axis of 
a telescope, a straight line passing through the centers 
of all the glasses in the tube. Axis of collineation, in 
math., a line which corresponds to itself in a projective 
transformation. Axis of direct elasticity, a direction 
in a solid body such that a longitudinal strain In that di- 
rection produces a stress precisely opposed to the strain. 
Axis of elasticity, a direction in a solid body with 
respect to which some kind of symmetry exists in the 
relation of strains and stresses. Axis of homology , the 
line upon which corresponding lines of two figures in 
homology intersect each other. Axis of oscillation of 
a pendulum, a right line passing through the center 
alxmt which it vibrates, and perpendicular to the plane 
of vibration. Axis of perspective, the line in which 
the plane of a perspective representation cuts any plane 
represented. Axis of reflection, in the method of in- 
version in geometry, any line considered as perpendicular 
to and bisecting the distance between two inverse points. 
Axis Of refraction, a straight line drawn perpendicular 
to the surface of the refracting medium, through the point 
of incidence of the refracted ray. Some crystals have two 
axes of refraction. Axis Of rotation, the imaginary line 
almut which all the parts of a rotating body turn. Axis 
of similitude of three circles, a line passing through 
two intersections of corresponding pairs of common 
tangents of two pairs out of the three circles. The axis 
of similitude also necessarily passes through a third such 
point, but this fact is not essential to its definition. 
Axis Of symmetry, a line on both or all sides of which 
the parts of a body or magnitude are symmetrically dis- 
posed. Axis Of the earth, the straight line connecting 
its two poles, and about which it performs its diurnal ro- 
tation. Axis of the eye, a straight line passing through 
the centers of the pupil and crystalline lens ; the optic 
axis. Axis of the Ionic capital, a line passing peri>en- 
dicularly through the middle of the eye of the volute. 
Axis Of the world, the imaginary axis passing through 
the celestial poles. Axis of vision. See rieual axis, be- 
low. Baslcranlal axis, a straight line drawn from a 
point midway between the occipital condyles, through the 
median plane of the skull, to the junction of the ethmoid 
and presplienolil, in the floor of the cerebral cavity. 
Huxley. See cut under craniofacial. Baslfacial axis, 
or facial axis, a straight line drawn from the anterior 
extremity of the premaxilla to the anterior extremity of 
the basicranial axis (which see, above): not to l>e con- 
founded with/V/em/ line. See craninmetry, and cut under 
'ranioj'wial. Cellac axis, (a) A short, thick branch of 
the abdominal aorta, given off just below the diaphragm, 
and immediately dividing into the gastric, hepatic, and 
splenic arteries. (6) The sympathetic plexus which sur- 
rounds this artery. Cerebrosplnal a^ See eerebro- 
spinal. Conjugate or minor axis, in geom., an axis, 
especially of a hyperlwla, perpendicular to the transverse 
avis. The term was originally used in the plural for a pair 
of conjugate diameters at right angles to each other. As 
no\\ used, it is an abbreviated expression for axis conju- 
gate to tin- t,-<iit*n-,-H> ajcix. Facial axis. -See brtsifncittl 
403 
nxitt, above. - Harmonic axis. *r><hnnmiti><-. Instan- 
taneous axis, l be axis about which a body is rotating at 
any inMaii! : an e\prc.--ioii applicable uiien motion is 
considered in only two dimensions or when a point of the 
body is fixed ; in other cases It would be an inaccurate 
abbreviation of the following: Instantaneous sliding 
axis, that line about which a body is rotating and alonk' 
whicli it is .simultaneously sliding at any instant. Every 
rigid body at every instant of its motion has such an in- 
stantaneous sliding axis. Macrodiagonal axis, mag- 
netic axis. See the adjectives. NCUTal aXlS, in nn'lt.. 
the rei ebrospinal a\is; the axis or central trunk of the 
ccrehroHpinai system. Neutral axis, in nn'<-lt.: (n) of a 
beam, the plane in which the tensile and compressing 
forces terminate, and in which the stress is therefore m< 
thing, (li) of a deflected bar, the line along which then- is 
neither extension nor compression. Optic axis, the axis 
of the eye (which see, above). - Orthogonal or principal 
metatatlc axes, three axes in a body such that, if a cube 
be cut out having its faces normal to these axes, and if 
there be a linear elongation along one of them and an 
equal linear compression along a second, no tangential 
stress will result round the third axis on planes normal 
to the first two. Radical axis of two circles, the line 
joining their pointe of intersection. This line is i.-al even 
when the circles do not really Intersect, the difference of 
its distance from the two centers being proportional to the 
difference of the areas of the two circles.- Spiral axis, 
in an-h., the axis of a twisted column spirally drawn in 
order to trace the circumvolutions without. Synclinal 
axis, in iiful. See synclinal. Tectonic axes, in crys- 
tal., the lines along which the minute crystals are ar- 
ranged in the formation of a complex crystalline growth. 
Thus, dendritic crystallizations of gold and copper often 
branch at angles of GO', their directions being parallel 
to the sides of an octahedral face. The principal axes 
of inertia of a body, those lines passing through its cen- 
ter of mass about which its moments of Inertia are a maxi- 
mum and a minimum, together with the third line per- 
pendicular to these at their intersection. The princi- 
pal axes Of stress in a body, the directions of the three 
conjugate normal stresses. Thyroid axis, a short, thick 
branch from the subclavian artery, dividing almost im- 
mediately Into the inferior thyroid, suprascapular, and 
transversalis colli. Transverse or major axis, in coY 
section*, the diameter which passes through the foci. In 
the ellipse it is the longest diameter ; in the hyperbola it 
is the shortest ; and in the parabola it is, like all the other 
diameters, infinite in length. Visual axis, in ph'jgiol., 
the straight line passing through the center of the pupil 
and the middle of the macula lutea. It does not coincide 
with the optic axis. Also called visual tine, or axis o/ 
nmVui. Zone axis. See zone. 
axis 2 (ak'sis), N. [L. axis (Pliny) ; perhaps of 
E. Ind. origin.] 1. A kind of East Indian 
deer, Cervius axis, of which there are several 
varieties, perhaps species. The body is spotted 
with white. Also called axig-deer, spotted deer, 
and hog-deer. 2. [cap.'] [NL.] A genus of 
such deer. Ham. Smith, 1827. 
axis-cylinder (ak'sis-sil'in-der), w. In anat., 
the central part of a nerve-fiber; the core of 
white nerve-tissue in a nerve-fiber, it is the es- 
sential part of the nerve, and is the only part found at 
its origin and termination. In cross-section, a bundle of 
nerve-fibers appears like a bunch of lead pencils, the axis- 
cylinder corresponding to the lead. Also called baiid-axi* 
and axix-band. 
axis-deer (ak'sis-der), . Same as axis'*, 1. 
axisynimetric(ak"'si-8i-met'rik), . Symmetri- 
cal with reference to an axis. 
axle (ak'sl). n. [Early mod. E. also axel, axell, 
axile, < ME. axel, axil (chiefly in comp. axel- 
tree, q. v. ; not in AS., where only the primitive 
a-x, tux occurs: see <u; 2 ) = Icel. oxall, m., = 
Sw. Dan. nxel, axle; not found in this sense in 
the other languages, where its place is supplied 
by the primitive ax*, but ult. = ME. cexl, exl, < 
axle-tooth 
Leading axle, in British 1 ...... motives, an axle of a wheel 
in front of the driving-wheels.- Hail axle, in r<inch-t>iiild- 
in'i, an axle which is secured by a plate at its back instead 
of a nut on tin- end. 
The commonest kind of oil axle is called the /,,ro7, be 
can-, the peculiar mode of fastening was first used in 
the mail coaches. J. W. Bury?**, Coach-Building, p. 1-1. 
Telescopic axle, an extension-axle which permits the 
running-wheels of a railroad-car to be slipped in or out. 
thu^ making them adaptable to tracks of different ^'aL--' 
Trailing axle, the rear axle of a locomotive. In Kng 
lish engines it is usually placed under the foot-plate. 
axle-adjuster (ak'sl-a-jus'ter), n. A machine 
for straightening axles; a machine used in giv- 
ing to the spindle its proper line of direction 
n-hitivoly to the axletree. 
axle-arm (ak'sl-arm), w. The spindle on the 
end of an axle on which the box of the wheel 
slips, or one of the two pivots on which the 
axle itself turns. See second cut under nsli- 
lui.r. 
axle-bar (ak'sl-biir), M. The bar of an axle- 
tree. 
axle-block (ak'sl-blok), M. The block placed 
upon the axle of a vehicle to form a seat for 
the spring when it is depressed. 
axle-box (ak'sl-boks), H. The box which con- 
tains the bearings for the spindle of an axle, or 
the journal of an axle, 
as of a carriage-wheel, a 
railroad-car wheel, etc. ; 
the bushing or metal 
lining of the hub whicli 
forms the rotatory bear- 
ing of the axle of a ve- 
hicle.- Axle-box guides, 
the guides for the brasses of 
an axle box. Radial axle- 
box, in a railroad-car, a slid- 
ing axle-box, so arranged that, 
with its fellow, it maintains 
the axle in a position radial to 
the curve of the track, how- 
ever its direction 
Railroad-car Axle-box. 
tt, axle ; *, journal ; c, sad- 
dle, by means of which the 
weight of the car rests on the 
journal ; ,/, chamber for a lu- 
bricating substance, having its 
lid at i. 
Miller's Rubber-cushioned Axle-boi. 
*. hub : ff, axle-box ; C. axle-arm : A 
rubber cushions ; E, compression-nut ; / . 
cavities in compression-nut admitting points 
of the wrench when compressing cushions ; 
G, slotted retaining-steeve ; //, spuron axle- 
box ; y, space between axle-box and hub. 
AS. eaxl, exel = OHG. ahsala, MHG. ahsrl, G. 
acliscl = Icel. oxl, {., = Sw. Dan. axel = Norw. 
okxl, akul, axel, the shoulder, = L. dla (for "ax- 
la), shoulder-joint, wing (see ala, aisle, and cf. 
axilla): with formative -I, < ax 2 (L. axix, etc.), 
axle (the shoulder-joint being the axle or axis 
on which the arm turns) : see ax 2 .] 1. The pin 
or spindle on which a wheel revolves, or which 
forms the axis of the wheel and revolves with it. 
Properly, the axle of a carriage-, cart-, or wagon-wheel is 
the round arm of the axletree or axle-bar which is inserted 
in the hub or nave, but the name is sometimes extended to 
the whole axletree. 
2f. An axis, as of the earth. 
Whether . . . 
He [the sun] from the east his flaming road begin, 
Or she [the earth] from west her silent course advance, 
With inoffensive pace that spinning sleeps 
On her soft axle. Milton, P. L., viii. 165. 
Axle stop-key, a plate upon the end of the axle of a ratl- 
road-car, intended to prevent excessive lateral motion and 
to take the wear. Blind axle, an axle that does not com- 
municate power ; a dead axle. Collinge axle, in coach- 
building, an axle the box of which is secured upon the 
arm by two nuts screwed right and left. Compound 
axle, an axle having two parts connected by a sleeve or 
some other locking arrangement. Dead axle, one which 
does not impart motion ; a blind axle : opposed to a lite axle. 
or driring-aaclt. Dipping the axle, in enarh-buililiun, 
bending the end of the axle so that the wheel shall strike 
squarely upon the ground. Driving-axle, in locomotive 
engines, the axle which receivesthe power from the 
steam-piston transmitted through the piston-rod and con- 
necting-rod. The rear end of the latter is connected 
either with cranks formed in this axle, or more generally 
with crank-pins upon the driving-wheels at its ends. 
may change. 
axle-clip (ak'sl- 
klip), ii. A 
clevis or bow 
which unites 
some other part 
of a vehicle to 
the axle Axle- 
clip tie, the cross- 
bar which joins 
and secures the 
ends of the how- 
clip (which see) 
V i > 
aXie-COliar 
( ak 'si ko] //: ir^ 
s' /' 
n. The collar 
on an axle which receives the lateral pressure 
from the wheel or bearing. 
axled (ak'sld), a. Furnished with an axle or 
with axles. 
axle-gage (ak'sl-gaj), . A wheelwright's in- 
strument for giving to the spindle of an axle its 
proper swing and gather. 
axle-guard (ak'sl-giird), w. Those parts of a 
railroad-car in which the axle-box plays verti- 
cally under the yield and reaction of the car- 
springs Axle-guard Stays, the iron rods or straps 
which are bolted to the frame and to all the ends of the 
axle-guards, to strengthen them. 
axle-hook (ak'sl-huk), n. A hook in front of 
the axle of a carriage, to which is attached the 
stay-chain connecting the axle and the double- 
tree. 
axle-nut (ak'sl-nut), M. A screw-nut fitted to 
the end of the arm of an axle to keep the wheel 
in place. 
axle-packing (ak'sl-pak'ing), M. The guard 
or material placed about an axle to exclude 
dust. 
axle-pin (ak'sl-pin), n. Same as linch-pin. 
axle-saddle (ak'sl-sad'l), n. A saddle-shaped 
clip, used in securing a spring to an axle. 
axle-seat (ak'sl-set). n. The hole in a rail- 
road-car wheel which receives the arm of the 
axle. 
axle-skein (ak'sl-skiin), n. A band, strip, or 
thimble of metal placed on a wooden axle-arm 
to prevent the wood from wearing rapidly. 
axle-sleeve (ak'sl-slev), . A sleeve placed 
round a railroad-car axle in order to hold up 
the ends should the axle be broken. 
axle-tooth (ak'sl-toth), n. [E. dial., also assle-, 
a~?te-, assal-tooth, early mod. E. axel-, axill- 
tooth, < late ME. axyltothe (= Dan. axel-land); 
< 'axel (Shetland yackle) (< Icel. jail = Norw. 
jaksle, jakle = Sw. dial, jakkel, jaksl = Dan. 
axel), a jaw-tooth, grinder, + tooth.'] A grind- 
er; a molar. [Prov. Eng.] 
