Homer's _Iliad_. His father was Peleus, ruler of Phthia in Thessaly, his
mother the sea-goddess Thetis. When only six years of age he was able to
overcome lions and bears. His guardian, Cheiron the Centaur, having
declared that Troy could not be taken without his aid, his mother, fearing
for his safety, disguised him as a girl, and introduced him among the
daughters of Lycomedes of Scyros. Her desire for his safety made her also
try to make him invulnerable when a child by anointing him with ambrosia,
and again by dipping him in the River Styx, from which he came out proof
against wounds, all but the heel, by which she held him. His place of
concealment was discovered by Odysseus (Ulysses), and he promised his
assistance to the Greeks against Troy. Accompanied by his close friend,
Patroclus, he joined the expedition with a body of followers (Myrmidons) in
fifty ships, and occupied nine years in raids upon the towns neighbouring
to Troy, after which the siege proper commenced. On being deprived of his
prize, the maiden Briseis, by Agamemnon, he refused to take any further
part in the war, and disaster attended the Greeks. Patroclus now persuaded
Achilles to allow him to lead the Myrmidons to battle dressed in his
armour, and he having been slain by Hector, Achilles vowed revenge on the
Trojans, and forgot his anger against the Greeks. He attacked the Trojans
and drove them back to their walls, slaying them in great numbers, chased
Hector, who fled before him three times round the walls of Troy, slew him,
and dragged his body at his chariot-wheels, but afterwards gave it up to
Priam, who came in person to beg for it. He then performed the funeral
rites of Patroclus, with which the _Iliad_ closes. He was killed in a
battle at the Scaean Gate of Troy by an arrow from the bow of Paris which
struck his vulnerable heel. In discussions on the origin of the Homeric
poems the term _Achilleid_ is often applied to those books (i, viii, and
xi-xxii) of the _Iliad_ in which Achilles is prominent, and which some
suppose to have formed the original nucleus of the poem. See _Iphigenia_.
ACHILLES' TENDON, or TENDON OF ACHILLES, the strong tendon which connects
the muscles of the calf with the heel, and which may be easily felt with
the hand. The origin of the name will be understood from the above article.
ACHILLES TATIUS (a-kil'[=e]z t[=a]'shi-us), a Greek romance writer of the
fifth century A.D., belonging to Alexandria; wrote a love story in 8 books
called _Leucipp[=e] and Cleitophon_.
ACHIMENES (a-kim'e-n[=e]z), a genus of tropical American plants, with scaly
underground tubers, nat. ord. Gesneraceae, now cultivated in European
greenhouses on account of their white, blue, and red flowers.
ACHLAMYDEOUS (ak-la-mid'i-us), in botany, wanting the floral envelopes,
that is, having neither calyx nor corolla, as the willow.
ACHOR ([=a]'kor), a disease of infants, in which the head, the face, and
often the neck and breast become incrusted with thin, yellowish or greenish
scabs, arising from minute, whitish pustules, which discharge a viscid
fluid.
ACHROMAT'IC (Gr. _a_, priv., and _chr[=o]ma, chr[=o]matos_, colour), in
optics, transmitting colourless light, that is, not decomposed into the
primary colours, though having passed through a refracting medium. A single
convex lens does not give an image free from the prismatic colours, because
the rays of different colour making up white light are not equally
refrangible, and thus do not all come to a focus together, the violet, for
instance, being nearest the lens, the red farthest off. If such a lens of
crown-glass, however, is combined with a concave lens of flint-glass--the
curvatures of both being properly adjusted--as the two materials have
somewhat different optical properties, the latter will neutralize the
chromatic aberration of the former, and a satisfactory image will be
produced. Telescopes, microscopes, &c., in which the glasses are thus
composed are called _achromatic_.
ACID (Lat. _acidus_, sour), a name applied to a number of compounds, having
more or less the qualities of vinegar (itself a diluted form of acetic
acid). Their general properties are sour taste, the power of changing
vegetable blues into reds, of evolving hydrogen in presence of magnesium,
of decomposing chalk with effervescence, and of being in various degrees
neutralized by alkalies. An acid has been defined as a compound of
hydrogen, the whole or a part of which is replaceable by a metal when this
is presented in the form of a hydroxide; being _monobasic_, _dibasic_, or
_tribasic_, according to the number of replaceable hydrogen atoms in a
molecule. See _Chemistry_.
ACIERAGE ([=a]'s[=e]-[.e]r-[=a]j), (Fr. _acier_, steel), a process by which
an engraved copper-plate or an electrotype from an engraved plate of steel
or copper has a film of iron deposited over its surface by electricity in
order to protect the engraving from wear in printing. By this means an
electrotype of a fine engraving, which, if printed directly from the
copper, would not yield 500 good impressions, can be made to yield 3000 or
more; and when the film of iron becomes so worn as to reveal any part of
the copper, it may be removed and a fresh coating deposited so that 20,000
good impressions may be got.
ACIPENSER (as-i-pen's[.e]r), the genus of cartilaginous ganoid fishes to
which the sturgeon belongs.
ACI REALE ([:a]'ch[=e] r[=a]-[:a]'l[=a]), a seaport of Sicily, north-east
of Catania, a well-built town, with a trade in corn, wine, fruit, &c. Pop.
35,587.
A'CIS, according to Ovid, a beautiful shepherd of Sicily, loved by Galatea,
and crushed to death by his rival the Cyclops Polyphemus. His blood,
flowing from beneath the rock which crushed him, was changed into a river
bearing his name, and renowned for the coldness of its water. It has been
identified as the Fiume di Jaci.
ACLIN'IC LINE (Gr. priv. _a, klin[=o]_, to incline), the magnetic equator,
an irregular curve in the neighbourhood of the terrestrial equator, where
the magnetic needle balances itself horizontally, having no dip. See
_Magnetism_.
ACNE (ak'n[=e]), a skin disease, consisting of small hard pimples, usually
on the face, caused by congestion of the follicles of the skin.
[Illustration: Acolyte]
ACOLYTES (ak'o-l[=i]ts), in the ancient Latin and Greek Churches, persons
of ecclesiastical rank next in order below the subdeacons, whose office it
was to attend the officiating priest. The name is still retained in the
Roman Church. Cf. Duchesne, _Christian Worship, its Origin and Evolution_.
ACONCAGUA ([.a]-kon-k[:a]'gw[.a]), a province, a river, and a mountain of
Chile. The peak of Aconcagua, whose summit is just within the Argentine
Republic, rises to the height of 23,080 feet, and is probably the highest
mountain of the western hemisphere. Area of province, 5406 sq. miles. Pop.
(1919), 132,165.
AC'ONITE (_Acon[=i]tum_), a genus of hardy herbaceous plants, nat. ord.
Ranunculaceae, represented by the well-known wolf's-bane or monk's-hood,
and remarkable for their poisonous properties and medicinal qualities,
being used internally as well as externally in rheumatism, gout, neuralgia,
&c.
ACON'ITINE, an alkaloid extracted from monk's-hood and some other species
of aconite; used medicinally, though a virulent poison.
ACONQUIJA ([.a]-kon-k[=e]'_h_[.a]), a range of mountains in the Argentine
Republic; the name also of a single peak, 17,000 feet high.
A'CORN, the fruit of the different kinds of oak. The acorn-cups of one
species are brought from the Levant under the name of _valonia_, and used
in tanning.
ACORN-SHELL. See _Balanus_.
AC'ORUS, a genus of plants, including the sweet-flag. See _Sweet-flag_ and
_Calamus_.
ACOS'TA, Gabriel, afterwards Uriel, a Portuguese of Jewish descent, born at
Oporto in 1590, died by his own hand 1640. Brought up a Christian, he
afterwards embraced Judaism. Having gone to Amsterdam, where he attacked
the practices of the Jews, and denied the divine mission of Moses, he
suffered much persecution at the hands of the Jews. He left an
autobiography, published in 1687, under the title _Exemplar Humanae Vitae_.
He is the hero of a novel, _Die Sadducaeer von Amsterdam_, and of a
tragedy, _Uriel Acosta_, both by Gutzkow.
ACOTYLE'DONS, plants not furnished with cotyledons or seed-lobes. They
include ferns, mosses, seaweeds, &c., and are also called flowerless plants
or cryptogams.
ACOUSIMETER, or ACOUMETER (Gr. _akouein_, to hear, and _metron_, measure),
an instrument used to determine the acuteness of hearing. It consists of a
small bar which gives a uniform sound when struck by a hammer.
ACOUSTICS (a-kou'stiks), the science of sound. It deals with the production
of sound, its propagation and velocity in various media; the reflection,
refraction, and interference of sound waves; the properties of musical
notes; and the general phenomena of such vibrations of elastic bodies as
affect the organ of hearing.
In order that a sound may be heard, it is necessary that an uninterrupted
series of particles of elastic matter should extend from the sounding body
to our ear. Sound is propagated by a longitudinal wave-motion in the medium
(gaseous, liquid, or solid), that is, the particles oscillate along the
line in which the wave is travelling, giving rise to regular series of
condensations and rarefactions.
The velocity of sound varies directly as the square root of the elasticity,
and inversely as the square root of the density, of the medium in which it
is propagated. The velocity of sound in air at 0deg C. is 330.6 metres per
second, or 1085 feet per second; in water 1.49 kilometres per second, or
0.926 mile per second; in copper 5.01 kilometres per second, or 3.12 miles
per second.
The intensity of sound varies inversely as the square of the distance from
the sounding body. Recently sound-ranging instruments have been produced by
means of which the position of a gun can be determined.
A note produced by a musical instrument consists of a _fundamental_ of a
certain frequency, together with a number of _overtones_ of various higher
frequencies and much smaller amplitude. The _timbre_ of a note depends on
the overtones present, the _loudness_ depends on the amplitude of the
vibrations, and the _pitch_ depends on the frequency. The musical scale
consists of eight notes, C D E F G A B C, whose frequencies are in the
proportion of the numbers 24, 27, 30, 32, 36, 40, 45 and 48. The interval
between two notes is the ratio of the frequency of the higher note to the
frequency of the lower note. In order that the intervals may be the same in
all keys, a tempered scale is used in music. (See Table, p. 25.)
BIBLIOGRAPHY: Lord Rayleigh, _Theory of Sound_; H. Smith, _The Making of
Sound in the Organ and Orchestra_; J. W. Capstick, _Sound_ (Cambridge
Natural Science Manuals); E. H. Barton, _Text-book of Sound_.
ACQUI ([.a]k'w[=e]), a town of Northern Italy, 18 miles S.S.W. of
Alessandria, a bishop's see. It has warm sulphurous baths, which were known
to the Romans, and which still attract a great many visitors. Pop. 16,500.
ACRE, a standard British measure of land, also used in the colonies and the
United States. The imperial statute acre consists of 4840 sq. yards,
divided into 4 roods. The old Scotch acre contains 6146.8 sq. yards, the
old Irish acre 7840 sq. yards.
ACRE ([=a]'k[.e]r) (ancient ACCHO and PTOLEMAIS), a seaport of Syria, in
Northern Palestine, on the Bay of Acre, early a place of great strength and
importance. Taken from the Saracens under Saladin in 1191 by Richard I of
England and Philip of France; bravely defended by the Turks, assisted by
Sir Sidney Smith, in 1799 against Napoleon; in 1832, taken by Ibrahim
Pasha; in 1840, bombarded by a British, Austrian, and Turkish fleet, and
restored to the Sultan of Turkey. The town was occupied by British troops
under General Allenby in September, 1918. Pop. 10,000.
* * * * *
MUSICAL INTERVALS.--See _Acoustics_
Intervals in Intervals in
Perfect Diatonic Diatonic Scale. Tempered Scale--
Scale. Perfect on System of Mean tone.
Diatonic Scale Equal (2^{1/6} = 1.123).
Temperament. Semitone.
(2^{1/12}= 1.059).
---------------------------------------------------------------------
C 1 1.000
9/8 major tone tone.
D 9/8 = 1.125 2-2/12 = 1.123
10/9 minor tone tone.
E 5/4 = 1.250 2-4/12 = 1.260
16/15 limma semitone.
F 4/3 = 1.333 2-5/12 = 1.335
9/8 major tone tone.
G 3/2 = 1.500 2-7/12 = 1.498
10/9 minor tone tone.
A 5/3 = 1.667 2-9/12 = 1.682
9/8 minor tone tone.
B 15/8 = 1.875 2-11/12 = 1.888
16/15 limma semitone.
C' 2 2.000
Major tone ratio = 9/8 = 1.125 Limma tone ratio = 16/15 = 1.067
Minor " " = 10/9 = 1.111 Semitone " = 2^{1/12} = 1.059
Mean " " = 2^{2/12} = 1.123
NOTES OF PERFECT DIATONIC SCALE (WITH THEIR FREQUENCIES)
C,, 64. Ut_1 C, 128. Ut_2 C 256. Ut_3 C' 512. Ut_4
D,, 72 D, 144 D 288 D' 576
E,, 80 E, 160 E 320 E' 640
F,, 85.3 F, 170.7 F 341.3 F' 682.7
G,, 96 G, 192 G 384 G' 768
A,, 106.6 A, 213.3 A 426.7 A' 853.2
B,, 120 B, 240 B 480 B' 960
C'' 1024. Ut_5
PERFECT DIATONIC SCALES (TRANSITION TO KEY OF DOMINANT)
_Example_--Key of C to Key of G
C D E F G A B C' D' E' F' G'
1 9/8 5/4 4/3 3/2 5/3 15/8 2 9/4 5/2 8/3 3
G A` B C' D' E' F'# G'
1 9/8 5/4 4/3 3/2 5/3 15/8 2
A = 10/9 G. F' = 16/9 G.
A`= 9/8 G. F'# = 15/8 G.
A`= 81/80 A. = 15/8 X 9/16 F'.
= (1 + 1/18{2/7}) F'.
* * * * *
ACRI ([=a]'kr[=e]), a town of S. Italy, province of Cosenza. Pop. 4000.
AC'RITA (Gr. _akritos_, undistinguishable, doubtful), a name sometimes
given to the animals otherwise called Protozoa.
ACROCEPH'ALI, tribes of men distinguished by pyramidal or high skulls.
ACROCERAU'NIA (thunder-smitten peaks) (now CAPE GLOSSA or LINGUETTA), a
promontory of Western Greece, in Epirus, running into the Adriatic.
ACROCORIN'THUS, a steep rock in Greece, nearly 1900 feet high, overhanging
ancient Corinth, and on which stood the acropolis or citadel, the sacred
fountain of Pir[=e]n[=e] being also here. This natural fortress has proved
itself of importance in the modern history of Greece.
AC'ROGENS (-jenz), lit. summit-growers, a term applied to the ferns,
mosses, and lichens (cryptogams), as growing by extension upwards, in
contradistinction to endogens and exogens.
AC'ROLITH, an early form of Greek statuary in which the head, hands, and
feet only were of stone, the trunk of the figure being of wood draped or
gilded.
ACROP'OLIS (Gr. _akros_, high, and _polis_, a city), the citadel or chief
place of a Grecian city, usually on an eminence commanding the town. That
of Athens contained some of the finest buildings in the world, such as the
Parthenon, Erechth[=e]um, &c.
ACROS'TIC, a poem of which the first or last, or certain other, letters of
the line, taken in order, form some name, motto, or sentence. A poem of
which both first and last letters are thus arranged is called a double
acrostic. In Hebrew poetry, the term is given to a poem of which the
initial letters of the lines or stanzas were made to run over the letters
of the alphabet in their order, as in _Psalm_ cxix.--Acrostics have been
much used in complimentary verses, the initial letters giving the name of
the person eulogized. They were very popular among French poets of the
sixteenth and seventeenth centuries. In modern times Edgar Allen Poe has
written quite remarkable acrostic verses.
ACT, in special senses: (1) In dramatic poetry, one of the principal
divisions of a drama, in which a definite and coherent portion of the plot
is represented; generally subdivided into smaller portions called _scenes_.
The Greek dramas were not divided into acts. The dictum that a drama should
consist of five acts was first formally laid down by Horace, and is
generally adhered to by modern dramatists in tragedy. In comedy, especially
since the time of Moliere, more freedom is allowed, and a division into two
or three acts is common.--(2) Something formally done by a legislative or
judicial body; a statute or law passed.--(3) In universities, a thesis
maintained in public by a candidate for a degree. See _Act of God_, _of
Parliament_, _of Settlement_.
ACTA DIUR'NA (Lat., proceedings of the day), a daily Roman newspaper which
appeared under both the republic and the empire.
ACTAE'A. See _Baneberry_.
ACTAE'ON, in Greek mythology, a great hunter, turned into a stag by
Art[)e]mis (Diana) for looking on her when she was bathing, and torn to
pieces by his own dogs.
ACTA ERUDITO'RUM (Lat., acts of the learned), the first literary journal
that appeared in Germany (1682-1782). It was started by Otto Mencke, after
the model of the _Journal des Savants_. Among the contributors, the most
distinguished was Leibnitz.
ACTA SANCTORUM (Lat., acts of the saints), a name applied to all
collections of accounts of ancient martyrs and saints, both of the Greek
and Roman Churches, more particularly to the valuable collection begun by
John Bolland, a Jesuit of Antwerp, in 1643, and which, being continued by
other divines of the same order (_Bollandists_), now extends to sixty
volumes, the lives following each other in the order of the calendar.
ACTIN'IA, the genus of animals to which the typical sea-anemones belong.
See _Sea-anemone_.
AC'TINISM, the property of those rays of light which produce chemical
changes, as in photography, in contradistinction to the light rays and heat
rays. The actinic property or force begins among the green rays, is
strongest in the violet rays, and extends a long way beyond the visible
spectrum.
ACTINIUM, an element or elementary substance obtained in minute quantities
in connection with the study of radioactivity. It was discovered by
Debierne in 1899. In 1902 Giesel discovered another substance which he
called _emanium_, and which was considered to be identical with _actinium_.
Marckwald, however, came to the conclusion that these two substances are
not identical but closely related to each other. See _Radium_, _Chemistry_.
ACTIN'OLITE, a mineral nearly allied to hornblende.
ACTINOM'ETER, an instrument for measuring the intensity of the sun's
actinic rays. See _Actinism_.
ACTINOZO'A (lit. ray-animals), a class of animals belonging to the
sub-kingdom Coelenterata, and including sea-anemones, corals, &c., all
having rayed tentacles round the mouth.
ACTION, the mode of seeking redress at law for any wrong, injury, or
deprivation. Actions are divided into civil and criminal, the former again
being divided into real, personal, and mixed.
AC'TIUM (now LA PUNTA), a promontory on the western coast of Northern
Greece, not far from the entrance of the Ambracian Gulf (Gulf of Arta),
memorable on account of the naval victory gained here by Octavianus
(afterwards the Emperor Augustus) over Antony and Cleopatra, 2nd Sept., 31
B.C., in sight of their armies encamped on the opposite shores of the
Ambracian Gulf. Soon after the beginning of the battle Cleopatra escaped
with sixty Egyptian ships, and Antony basely followed her, and fled with
her to Egypt. The deserted fleet was not overcome without making a brave
resistance. Antony's land forces soon went over to the enemy, and the Roman
world fell to Octavianus. In 1538 a victory was gained at Actium by the
Turks over the Spanish and Venetian fleets.
ACT OF GOD, a legal term defined as "a direct, violent, sudden, and
irresistible act of nature, which could not, by any reasonable cause, have
been foreseen or resisted". No one can be legally called upon to make good
loss so arising.
ACT OF PARLIAMENT, a law or statute proceeding from the Parliament of the
United Kingdom passed in both houses, and having received the royal assent.
Before it is passed it is a _Bill_ and not an Act. Acts are either public
or private, the former affecting the whole community, the latter only
special persons and private concerns. The whole body of public Acts
constitutes the _statute law_. An Act of Parliament can only be altered or
repealed by the authority of Parliament. Acts are usually cited in this
way, "13 and 14 Vict. c. (or chap.) 21", which means the 21st Act in
succession passed in year 13th-14th of the queen's reign (that is, 1850).
Short titles, such as "the Merchant Shipping Act, 1854", are also used. Up
to the time of Edward I Acts of Parliament were in Latin; then French was
introduced, and for some time was exclusively employed. It was not till
Henry VII's reign that all Acts were in English.
ACT OF SETTLEMENT, an Act passed by the English Parliament in 1700, by
which the succession to the throne of the three kingdoms, in the event of
King William and Princess (afterwards Queen) Anne dying without issue, was
settled on the Princess Sophia, electress of Hanover, and the heirs of her
body, being Protestants. The Princess Sophia was the youngest daughter of
Elizabeth, Queen of Bohemia, daughter of James I. By this act George I, son
of the Princess Sophia, succeeded to the crown on the death of Queen
Anne.--Another Act of Settlement was that by which, under Cromwell's
government, a new allotment was made of almost all landed property in
Ireland, in 1652.
ACT OF TOLERATION, an Act of Parliament Passed in 1689, by which Protestant
dissenters from the Church of England, on condition of their taking the
oaths of supremacy and allegiance, and repudiating the doctrine of
transubstantiation, were relieved from the restrictions under which they
had formerly lain with regard to the exercise of their religion according
to their own forms.
ACT OF UNIFORMITY, an English Act passed in 1662, enjoining upon all
ministers to use the _Book of Common Prayer_ on pain of forfeiture of their
livings. See _Nonconformity_.
[Illustration: Quilted Acton of the fifteenth century]
ACTON, a kind of padded or quilted vest or tunic formerly worn under a coat
of mail to save the body from bruises, or used by itself as a defensive
garment. Jackets of leather or other material plated with mail were also so
called. _Gambeson_ was an equivalent term.
ACTON, a name of various places in England, one of them a western suburb of
London, pop. (1921), 61,314. Since 1918 Acton gives its name to a
parliamentary division of Middlesex, returning one member to Parliament.
ACTON, John Emerich Edward Dalberg, first Baron Acton, born 1834, died
1902, was son of Richard Acton (seventh baronet) and the daughter of the
Duc de Dalberg, afterwards wife of Earl Granville, Mr. Gladstone's
colleague. As a Roman Catholic he was educated at Oscott, and afterwards on
the Continent, partly under Doellinger, and acquired a special taste for
and profound knowledge of history. He conducted the _Home and Foreign
Review_ from 1862 to 1864, and, in doing so, showed himself a strong
opponent of ultramontane pretensions. He next edited the _North British
Review_, which under him was rather overweighted with learning, and soon
came to an end. In 1869 he was raised to the peerage. He strongly opposed
the papal-infallibility movement, and took the side of Mr. Gladstone in his
attacks on Vaticanism. In 1895 he accepted the professorship of modern
history at Cambridge, delivered lectures, and planned and undertook the
editorship of the great work on modern history, _The Cambridge Modern
History_, comprising a series of contributions by various scholars, and
issued by the university press. Except essays, letters, or articles for
periodicals, he himself wrote little. Since his death have been published:
_Lectures in Modern History_ (1906); _The History of Freedom and other
Essays_ (1907); _Lectures on the French Revolution_ (1910). His library of
60,000 volumes he left to Mr. (now Lord) Morley, who handed it over to the
University of Cambridge.
ACTOR, one who represents some part or character on the stage. Actresses
were unknown to the Greeks and Romans in the earliest times, men or boys
always performing the female parts. They appeared under the Roman empire,
however. Charles II first encouraged the public appearance of actresses in
England; in Shakespeare's time there were none. See _Drama_.--BIBLIOGRAPHY:
C. F. Armstrong, _Century of Great Actors_; H. Simpson, _Century of Great
Actresses_.