perspective 
i i-ts consequently nnd il nei-esaary to m<xllfy the forms 
whii-h strlet perspective would prescribe. To ascertain 
li.iu n nrii/iiuil line or plant (that Is, a line or plane In 
nature) Is to be delineated, we have to consider, first, the 
intrnectiivj jxiiiit or line, also called the ItlttTHtua* of the 
oriijiital line ur plane (that i, the point or line where the 
original line or plane, extended if necessary, cuts the 
.i' ilfliiiriitii'n, or the plane of the picture extended 
to infinity); and, second, the vanishing p<nnt of the original 
line, or the vanithiivj line of the original plane (that is, 
the paint or line where the plane of delineation is cut by 
a Inn- <>r ,lane ]i:i"inn tliriiiiiili the eye parallel to the 
oriKlnnl line or plane). An original line Is represented by 
some portion of the line from its intersecting point to Its 
vanishing point ; and every line in a Riven original plane 
has its itih-rsertiiiy point on tin- int'-i <--i tiiiu r lint- and its 
vanishing point on the vanishing line of that plane. It 
is also proper to consider the directing plane, or plane 
through the eye parallel to the picture ; the directing lint, 
or line In which the directing plane cuts an original plane ; 
the directing point, or point in which the directing plane 
is pierced l)y an original line ; and the director, or line from 
the eye to a directing point. It is further necessary to 
take account of the direct radial, or principal visual rail, 
being the perpendicular let fall from the eye upon the 
plane of delineation ; the center of the picture, or center of 
vision (called by old writers the itoint of right), being the 
foot of that perpendicular ; and the principal distance, or 
distance of tfte picture, being the perpendicular distance 
of the plane of delineation from the eye. The ground- 
plane is the level plane on which the spectator is supposed 
to stand. The horizontal line, or horizon, is the line in 
which the level plane through the eye cuts the picture, 
passing ordinarily through the center. This would better 
be termed the horizontal line at infinity, for, owing to the 
dip of the horizon (which see, under dip\ it differs sensi- 
bly from the delineation of the true horizon. Linear per- 
spective is merely a branch of descriptive geometry, itself 
an application of projective geometry. Perspective is in- 
timately connected with the arts of design, and is particu- 
larly necessary in the art of painting, as without a correct 
ibstTvance of perspective no picture can have truth. Per- 
spective is illustrated in the correctdelineation of even the 
simplest positions of object*. 
4. A drawing or representation in perspective ; 
specifically, a painting so placed at the end of 
an alley, a garden, or the like, as to present 
the appearance of continuing it, and thus pro- 
duce the impression of greater length or ex- 
tent. Stage scenic painting is of this nature. 
Towards his study and bedchamber Joynes a little gar- 
den, which, tho' very narrow, by the addition of a well 
painted perspective is to appearance greatly enlarged. 
Evelyn, Diary, March 1, 1644. 
5. Prospect; view; vista. 
Perspectives of pleasant glades. Dryden. 
I saw a long perspective of felicity before me. 
i ;../:!> in HI,. Citizen of the World, xxx. 
Imagination had ample range in the boundless perspec- 
tive of these unknown regions. 
Prescott, Ferd. and Isa., 11. 26. 
6. Proper or just proportion ; appropriate rela- 
tion of parts to one another and to the whole 
view, subject, etc. 
We have endeavoured, in these our partitions, to ob- 
serve a kind of perspective, that one part may cast light 
upon another. Bacon, Advancement of Learning, ii. 171. 
Mr. Webster . . . never indulged in a weak flourish, 
though he knew perfectly well how to make such exordi- 
ums, episodes, and perorations as might give perspective 
to his harangues. Emerson, Fugitive Slave Law. 
Cromwell, we should gather, had found out the secret 
of this historical perspective, to distinguish between the 
blaze of a burning tar-barrel and the final conflagration of 
all things. Lowell, Among my Books, 1st ser., p. 260. 
Aerial perspective, in painting the art of giving due 
diminution to the strength of light, shade, and colors of 
objects according to their distances, to the quantity of 
light falling on them, and to the medium through which 
they are seen. 
The painter can imitate the aerial perspective. . . . Bat 
he cannot imitate the focal perspective, and still less can 
he imitate the binocular perspective. 
Le Conte, Sight, p. 144. 
Angular perspective. See angular. Axis of perspec- 
tive. Seearrwi. Center of perspective. See center!. 
Conical perspective, the art of delineating objects as 
if they were projected upon a conical surface from a point 
on its axis, this surface being subsequently developed. 
Curious perspective, the art of delineating objects so 
that, when the image of the picture in a curved mirror of 
definite form and position is viewed from a fixed station, the 
objects appear as in nature. Cylindrical perspective, 
that variety of conical perspective in which the cone 01 
delineation is a cylinder. Gauche perspective. See 
yauche. In perspective, according to the laws of per- 
spective ; hence, represented on a flat surface in such a 
way as to convey the idea of solidity and distance. In- 
verse perspective, the art of interpreting pictures in 
perspective so as to ascertain the proper position of the 
eye and the relative positions ana forms of the objects 
represented. Isometric perspective. See isometric. 
Linear perspective. See linear. Oblique perspec- 
tive. Same as angular perspective. Panoramic per- 
spective, that variety of cylindrical projection in wnich 
the cylinder of delineation is vertical. Parallel per- 
spective the perspective of a delineation in which the 
plane of the picture is parallel to the side of the principal 
object. Perspective plane, the surf ace on which the ob- 
ject or picture is delineated, or the transparent surface or 
plane through which the objects represented may be sup- 
posed to be viewed. It is also called plane of projection, 
plane of the picture, pichm-plane. Projected perspec- 
tive, a modification of ordinary perspective in which the 
picture is further from the eye than the original objects. 
4417 
perspective-instrument (n*r-pek'tiT-to*Bte9- 
ment), . Any mechanical aid in perspective 
drawing; a perspectograph. It may be a camera 
lucida, a camera obscura, an arrangement of movable 
strings or wires in connection with an eyepiece, or any- 
thing similar. 
perspectively (per-spek'tiv-li), <idc. If. Op- 
tieally; as through some optical instrument. 
Sec jM-rn/urlirr, n., 1. 
Yes, my lord, you see them pertpectivcly, the cities turned 
Into a maid, for they are all girdled with maiden walls, 
that war hath never entered. Shale. , lieu. V., v. 2. 347. 
2. According to the rules of perspective. 
perspectograph (per-spek'to-graf), . [< I... 
Iterspi-ctii.t (SIT i>crx/M.-i-tiri') + Gr. -jpatytiv, write.] 
An instrument of various forms for obtaining 
or transferring to a surface the points and out- 
lines of original objects in their true relations. 
perspectography (per-spek-tog'ra-fi), n. [< L. 
IH-rK/>eftus (see perspective) + Gr. -ypuQia, \ypa- 
ijxiv, write.] The science or theory of perspec- 
tive ; the art of delineating objects according 
to the rules of perspective. 
perspicable (per'spi-ka-bl), a. [< LL. perspi- 
ciiliiliu, < L. perspicere, look through: see per- 
spicuous.] Discernible; perceptible. 
The sea, . . . to the eye without any perspicable motion. 
Sir T. Herbert, Travels In Africa, p. 188. 
perspicacious (per-spi-ka'shus), a. [= F. per- 
spicace = Sp. Pg. perspicaz = It. pernpienee, < 
L. perspicax (perspicae-), sharp-sighted, < pcr- 
spicere, see through : see perspective.] 1. Quick- 
sighted; sharp of sight. 
And it [conscience] is altogether as nice, delicate, and 
tender in feeling as it can be perspicacious, and quick in 
seeing. South, Sermons, II. \ ii. 
2. Of acute discernment. 
Your perspicacious wit, and solid judgment, together 
with your acquired learning, render (you) every way a 
most accomplish'd and desirable patron. 
Cvdu-orth, Intellectual System, Ded. 
The . . . bewilderment of a respectable country gentle- 
man of kindly heart, irritable temper, and not too perspi- 
cacious brain, to whom the Fairy Mab had assigned such 
a son as Bysshe. /-.'. Dowden, Shelley, I. 120. 
Syn. Acute, shrewd, clear-sighted, sharp-witted. See 
astute. 
perspicaciously (per-spi-ka'shus-li), adr. In 
a perspicacious manner; with quick discern- 
ment. 
perspicaciousness (per-spi-ka'shus-nes), n. 
The character of being perspicacious ; acute- 
ness of sight; perspicacity. 
perspicacity (per-spi-kas'i-ti), n. [< F. perspi- 
caritt = Sp. perspicacidad = Pg. perspicacidade 
= It. perspicacita, < \Ai.perspicacita(t-)s, sharp- 
sightedness, < L. perspicajc (perspicae-), seeing 
through : see perspicacious.] The state or char- 
acterof being perspicacious, (a) Keenness or quick- 
ness of sight. 
Nor can there anything escape the perspicacity of those 
eyes which were before light. 
Sir T. Browne, Vulg. Err., L 2. 
('0 Acuteness of discernment or understanding ; penetra- 
tion ; sagacity : as, a man of great perspicacity. 
Although Clod could have given to us such perspicacity 
of intellect that we should never have erred, we have, not. 
withstanding, no right to demand this of him. 
Descartes, Prin. of Philos. (tr. by Veitch), I. 5 38. 
= Syn. (6) Sagacity, etc. (see judgment), Insight 
perspicacyt (per'spi-ka-si), n. [= Sp. Pg. It. 
pcrspicacia, < L. perspicax (perspicae-), sharp- 
sighted: see perspicacious.] Perspicacity. 
You have this gift of pcrspicacy above others. 
B. Jonson, Every Man out of his Humour, v. 2. 
perspiciencet (pfer-spiah'ens), n. [< L. pcrspi- 
cieittia, < perspicien(t-)s, ppr. ot perspicere, look 
through : see perspective.] The act of looking 
with sharpness. Bailey. 
perspicilt (per'spi-sil), n. [< ML. perspicilliim, 
a magnifying-lens, pi. perspicilla, spectacles, < 
L. perspicere, look through: see perspicuous, 
perspective. Cf. ML. conspicilla, spectacles, 
similarly related to conspicuous, etc.] A mag- 
uifying-glass ; a lens ; a telescope. 
Bring all your helps and perspieils, 
To see me at best advantage, and augment 
My form as I come forth. 
B. Jonson, Staple of News, i. 1. 
Sir, 'tis a perspicU, the best under heaven. 
With this 111 read a leaf of that small Iliad . . . 
Twelve long miles off. Tomlcis (l\ Albumazar, I. 8. 
perspicillumt (per-spi-sil'um), n. [ML. : see 
l>fi'*l>icit.] Same as perspicil. 
In these investigations he [Harvey] used a pmpirittum 
or simple lens. Encyc. Brit., XI. 604. 
perspicuity (per-spi-ku'j-ti), . [< F. penspicu- 
ite = Sp. perxpicuidad = Pg. perspicuidane = It. 
nerspicuita, < L. perspicttita(t-)s, transparency, 
< jxrspicuus, transparent: see perspicuous.] If. 
perspiration 
The quality of ln-in^ perspicuous or transpa- 
rent; that quality of ;i substance which renders 
objects visible through it; transparency; elear- 
nesH. 2. The quality of being clear to the 
mind, or easily apprehended or understood; 
clearness to mental vision ; freedom from ob- 
seurity or ambiguity ; that quality of writing 
or language which readily presents to the mind 
of another the precise ideas of the author; 
clearness. 
And, asmuch as you may, frame your stile lu perspicuity 
and to be sensible ; for the haughty obscure verse doth 
not much delight. 
Qascoigne, Steele Olas (ed. Arber), p. 86. 
Perspicuity consists In the using of proper terms for 
the ideas or thoughts which (a man) . . . would have 
pass from his own mind into that of another. 
/.*, Reading and Study. 
If Clearness and Perspicuity were only to be coniulted, 
the I'oet would have nothing else to do but to cloath his 
Thoughts In the most plain and natural Expressions. 
Addison, Spectator, No. 285. 
= Syn. 2. Perspicuity, Lucidity, Clearness, Plainness. These 
words, as expressing a quality of style, suggest much of 
their original meaning. Perspicuity Is the quality by which 
the meaning can be seen through the words, transparency. 
Lucidity expresses the same Idea, or the other meaning of 
lucid, that of the radiation or shining forth of the idea from 
language. Clearness may have two aspects, corresponding 
to the clearness with which one sees an object as separate 
from other things, or to the clearness of water when It Is not 
darkened in any way. Plainness rests upon the idea that 
nothing rises up to Intercept one's view of the thought ; it 
therefore implies, as the others do not, a simpler and home- 
lier diction, etc. Clearness or perspicuity is the common 
heading for that department of rhetoric which treats of 
Intelligibility in methods of expression, 
perspicuous (per-spik'u-us), a. [= Sp. Pg. It. 
perspicuo, < L. perspicuus, transparent, clear, 
evident, < perspicere, see through: see pcr- 
speclire.] If. Capable of being seen through ; 
transparent ; translucent. 
As contrary causes produce the like effects, so even the 
same proceed from black and white ; for the clear and 
pcrtpicttuM body effecteth white, and that white a black. 
Pcacham. 
2f. Obvious; plainly to be seen ; conspicuous; 
evident. 
The purpose is perspicuous even as substance, 
Whose (crossness little characters sum up. 
Shak., T. and C., i. 8. 324. 
For the mines that are now so perspicuous, and by him 
[Bellonlus) related, doe stand foure miles Southwest from 
the aforesaid place [TroyJ. Sandys, Travalles, p. 17. 
The common Gull, so perspicuous a Fop, the Women 
find him out, for none of em will marry him. 
Wycherley, Love in a Wood, Iv. I. 
3. Clear to the understanding; that may be 
easily apprehended or clearly understood ; not 
obscure or ambiguous; lucid: as, ^perspicuous 
statement. 
The Language of an Heroic Poem should be both Per- 
spicuous and Sublime. Addison, Spectator, No. 286. 
= 8yn.3. See perspicuity. 
perspicuously (per-spik'u-us-li), adv. In a per- 
spicuous manner; clearly; plainly. 
perspicuousness (per-spik'u-us-nes), . The 
state of being perspicuous; perspicuity; clear- 
ness to intellectual vision ; plainness ; freedom 
from obscurity or ambiguity. 
perspirability (per-spir-a-bil'i-ti), . [< per- 
spirablc + -ity (see -bility).] The property of 
being perspirable. 
perspirable (per-spir'a-bl), a. [= F. perspirable 
= It. persjrirabile ; as perspire + -able.] 1. Ca- 
pable of being perspired or evacuated through 
the pores of the skin. 
There are likewise aliments more or less perspirable. 
Artmthnot, Diet, I. 
2t. Capable of perspiring or emitting perspira- 
tion. 
Hair coraeth not upon the palms of the hands or soles 
of the feet, which are parts more perspirable. Bacon. 
perspirate (per'spi-rat), . i. ; pret. and pp. per- 
spirateii, ppr. peritpirating. [< L. perspiratus, 
pp. of pcrspirare, perspire: see perspire.] To 
perspire ; sweat. [Bare.] 
I perspirate from head to heel. 
Thackeray, Tltiuarsh's Carmen Lilllense, lii. 
perspiration (per-spi-ra'shon), n. [< F. per- 
api ration = Sp. /tei'spiracion = It. perspiraaone, 
< L. *pcrx])ii'<ttio(n-), < pergpiratux, pp. of per- 
spirare, perspire: see perspire.] 1. Kzcretion 
of liquid from the skin, mainly by the sweat- 
glands; sweating: a function of service in the 
elimination of certain substances, but especially 
as a means of cooling the body. It is underdirect 
nervous control. 2. The liquid thus excreted ; 
sweat. It consists of water holding 1 to 2 per cent 
of other substances, including sodium chlorid, various 
fatty acids, neutral fats, and cholesterin. Insensible 
perspiration, perspiration which is so small in quantity 
as to evaporate entirely and immediately. Sensible 
