matters, for they include not only most of the vegetable dye-stuffs, e.g.
madder, logwood, fustic, &c., but also many valuable fast coal-tar colours,
commonly known as the _alizarin dyes_, after their typical representative,
alizarin. These mordant dyes have by themselves very little colouring
power, as a rule, and if employed alone in dyeing give little or no result.
If applied, however, in conjunction with metallic salts, notably those of
chromium, aluminium, iron, tin, and copper, they each yield a variety of
colours, according to the metallic salt employed. In employing them two
distinct operations are usually involved: first, that of applying the
metallic salt or _mordant_, called the _mordanting process_; and second,
that of _dyeing_ proper, in which the mordanted material is boiled in a
solution or decoction of the dye-stuff. During the dyeing operation the
colouring principle of the dye-stuff combines with the metallic salt
already upon the material, and the colour is thus produced and fixed upon
the fibre. The method of mordanting varies with the fibre and the metallic
salt employed. The vegetable dye-stuffs of this class include _Madder_,
_Sapanwood_, _Camwood_, _Barwood_, _Old Fustic_, _Young Fustic_,
_Quercitron Bark_, _Persian Berries_, _Weld_, _Logwood_ (see these separate
articles). _Madder_ was formerly the most important and highly valued of
the dye-stuffs of this class, being especially employed to produce the fine
'Turkey-red' dye; but it is now entirely superseded by the coal-tar colour
alizarin. Similarly, the employment of _cochineal_ (an insect dye) has also
greatly diminished through the introduction of the cheaper colours.
_Camwood_ and _barwood_ are almost entirely used in wool-dyeing, either in
conjunction with the indigo-vat or for the purpose of dyeing various shades
of brown. _Old fustic_ is the most important of the yellow mordant
dye-stuffs, and the colours are fast although not very brilliant.
_Quercitron bark_ is an excellent dye-stuff employed by wool-dyers for the
production of bright orange and yellow colours. _Persian berries_ and
_weld_, a species of wild mignonette, are both excellent dye-stuffs, but
their employment is now limited. _Logwood_ is largely employed by wool,
silk, and cotton dyers for dyeing black and dark-blues, which, although
fast to washing, are only moderately so towards light. The important
vegetable dye _catechu_ (q.v.) is used in dyeing cotton and wool brown. On
wool, catechu yields _khaki_ browns in single bath by using copper sulphate
as the mordant. On silk, it is largely employed for weighting purposes in
the process of dyeing black. Although dyewoods are still much employed,
they are being steadily replaced by coal-tar colours. The _vat dyes_ are
insoluble in water, but yield reduction products which are soluble in
aqueous alkali, and can be readily reoxidized to the dye-stuff. In this
class may be included the _sulphur dyes_, substances of uncertain
composition obtained by fusing certain compounds containing nitrogen with
sulphur and sodium sulphide, which are now extensively and increasingly
employed, especially as direct dyes for cotton. _Indigo_, a typical vat
dye, is prepared both artificially and from natural sources. It is a
dark-blue powder quite insoluble in water, but when reduced it yields
_indigo-white_ which dissolves in aqueous alkali, the solution thus
obtained being called an _indigo-vat_. Cotton, wool, or silk steeped for
some time in the clear yellow solution of such a vat, and then exposed to
the oxidizing influence of the air, is dyed a permanent blue. The
indigo-white absorbed by the fibre loses its acquired hydrogen, and thus
insoluble indigo-blue is regenerated within and upon the fibre.
In the classification adopted above, the following _mineral colours_
employed in cotton dyeing belong to the group of developed dyes, since they
are formed on the fibre: _chrome yellow_, obtained by immersing cotton
successively in solutions of acetate of lead and bichromate of potash;
_iron buff_ (oxide of iron), produced by the successive application of
sulphate of iron and carbonate of soda; _Prussian blue_, developed by
passing the buff-dyed cotton through an acidified solution of potassium
ferrocyanide; _manganese brown_ (oxide of manganese), deposited similarly
to iron buff. The mineral colours are very useful for certain purposes, and
are very fast to light.--BIBLIOGRAPHY: Crookes, _A Practical Handbook of
Dyeing and Calico-printing_; W. P. Dreaper, _Chemistry and Physics of
Dyeing_; Knecht, Rawson, and Loewenthal, _Manual of Dyeing_; Rawson,
Gardner, and Laycock, _A Dictionary of Dyes, Mordants, &c._
DYER, John, English poet, born in Carmarthenshire about 1700, died in 1758.
Educated at Westminster School, he became a painter, but, not succeeding in
that vocation, took orders and was appointed to a small living. In 1727 he
published his poem of _Grongar Hill_, in 1740 _The Ruins of Rome_, and in
1757 _The Fleece_, a didactic poem in five books.
DYER'S-BROOM, a European and now also N. American shrub (_Genista
tinctoria_), formerly used with woad for dyeing green.
DYER'S-WEED, _Res[=e]da Lute[)o]la_, a British plant of the same genus as
mignonette, otherwise called _Yellow-weed_, _Weld_, or _Woad_, nat. ord.
Resedaceae. This plant grows in waste ground; it affords a beautiful yellow
dye, and is cultivated for that purpose.--_Dyer's Greenweed_ is _Genista
tinctoria_.
DYING DECLARATION, a deposition made by one who is in prospect of death.
Such declarations are as a general rule admissible as evidence only in
criminal and not in civil cases, and must be made, according to English,
though not Scottish law, in the full consciousness of the danger of death.
DYNAM'ICS is the science which deals with the laws of force in their
relation to matter at rest or in motion, and as such it is differentiated
from _kinematics_, which considers motion mathematically, and apart from
the forces producing it. Dynamics is divided into two great branches:
_statics_, which treats of solid bodies at rest under the action of forces;
and _kinetics_, which treats of the action of forces in producing motion in
solid bodies. Formerly the latter alone was called dynamics, and to this,
in conjunction with statics, the general name _mechanics_ was given. In the
wide sense dynamics includes also hydrodynamics. It is to Newton that we
owe the clear statement of the three primary laws of force on which the
science of dynamics is based. These are: (1) that every body remains in a
state of rest, or of uniform motion along a straight line, unless it is
compelled by force to change that state; (2) that rate of change of
momentum is in proportion to the force employed, and occurs along the
straight line in which the force acts; (3) that, as the result of every
action, there is always an equal and opposite reaction. These laws, which
were formulated from experiment, involve the conception of force as a
primary influence or action expressed in terms of space, time, and matter.
Now, in dealing with the laws of force, a standard of measurement is
required which shall be applicable to all forces at all times, and we
therefore require to begin by establishing units of space, time, and mass.
There are two systems of units in use, the one British, the other French.
In the British system the foot is taken as the unit of length, and the
second as the unit of time. In the French the centimetre is the unit of
length, the second the unit of time; the unit velocity in the one case
being that of one foot per second, in the other one centimetre per second.
The British unit of mass is the pound (the mass of a certain lump of
platinum deposited in the Exchequer Office, London); the French the gramme;
and accordingly the French units of space, mass, and time are commonly
known as the C.G.S. (centimetre, gramme, second) units. As the weight of a
pound (or a gramme) is not the same at all parts of the earth's surface, it
cannot give us of itself an absolute or dynamical unit of force, that is,
an invariable unit; but taking it in conjunction with unit time and unit
velocity, we do obtain such a unit. Two absolute units of force are in
common use in dynamics, the _poundal_ and the _dyne_, the latter being the
absolute unit in the C.G.S. system. The former is _that force which, acting
on the mass of one pound for one second, generates in that mass a velocity
of one foot per second_. The latter is _that force which, acting on the
mass of one gramme for one second, generates in that mass a velocity of one
centimetre per second_. It is important in dynamics to distinguish between
_mass_ and _weight_. The _mass_ of one pound is the quantity of matter
equal to a certain standard quantity (a certain lump of metal) and is quite
independent of force. The _weight_ of one pound is the force with which the
mass of one pound is attracted to the earth's surface by the force of
gravity. Another important term is _momentum_: the momentum of a body in
motion at any instant is the product of the mass of the body and the
velocity at that instant. See _Couple_; _Elasticity_; _Energy_; _Force_;
_Hydrodynamics_; _Kinematics_; _Kinetics_; _Statics_; _Thermodynamics_;
_Waves_.--BIBLIOGRAPHY: Kelvin and Tait, _Natural Philosophy_; A. Gray,
_Dynamics_; P. G. Tait, _Dynamics_; S. L. Loney, _Mechanics and
Hydrostatics for Beginners_.
DYN'AMITE. See _Explosives_.
DY'NAMO. See _Generator_.
DYNAMOM'ETER, an apparatus for measuring the power or rate of working of a
machine. There are two types, the transmission dynamometer, which measures
the power of the machine without sensibly diminishing it; and the
absorption dynamometer, which measures the power by using it all. The
instrument is generally employed to determine the horse-power transmitted
by a shaft or by belting.--Cf. Aspinall Parr's _Electrical Engineering
Testing_.
DYRRHACHIUM. See _Durazzo_.
DY'SART, a royal and municipal burgh of Scotland, in Fife, on the Firth of
Forth. It is an old place, and is a member of the Kirkcaldy district of
parliamentary burghs. Pop. of royal burgh, 4197.
DYS'ENTERY is a disease of an acute type, due to the action of a bacillus,
characterized by pain and frequent passage of blood and mucus. Owing to
improved sanitation, dysentery has become less frequent. In temperate
countries sporadic cases occur from time to time, and occasional epidemics
break out, but in the tropics widespread epidemics occur, and the disease
is a serious menace. It is a very frequent camp disease, and has been the
scourge of all armies in tropical and semi-tropical regions. The bacilli
are widely spread by the faeces of infected persons, and usually the
infection takes place by the mouth. The onset is rapid, and marked by
fever, pain in the abdomen, and frequent stools. At first mucus only is
seen in the stools, but soon blood appears. In very acute cases the patient
is seriously ill in forty-eight hours, and may die on the third or fourth
day. Moderate cases may go on for several weeks, with resulting
convalescence. Some cases become chronic in type, and a person may have
chronic dysentery for years. Bismuth in large doses is given, and morphia
is a most useful drug to relieve the pain and quieten the bowel. Normal
saline solution is given by rectum after the acute stage, whenever
possible. Chronic dysentery requires dietetic treatment for the persistent
dyspepsia and irritability of the bowel. Amoebic dysentery, due to the
_Amoeba dysenteriae_, is a distinct disease.
DYS'ODILE, a yellowish or greenish foliated carbonaceous substance found in
Sicily originally, and derived from the decay of minute organisms. When
ignited, it burns and emits a very unpleasant smell.
DYSON, Sir Frank Watson, F.R.S., LL.D.(Edin.), British astronomer, born at
Ashby 8th Jan., 1868, the son of a Baptist minister. Educated at Bradford
Grammar School and Trinity College, Cambridge, he became chief assistant at
the Royal Observatory, Greenwich, in 1894, and secretary of the Royal
Astronomical Society in 1899. Astronomer Royal for Scotland in 1905, he was
appointed Astronomer Royal for England in 1910. He was knighted in 1915.
DYSPEP'SIA, or GASTRITIS, may be either acute or chronic. _Acute dyspepsia_
may follow when more food is taken than the stomach can digest, or when
unsuitable articles are taken. The symptoms are headache, depression,
nausea, vomiting, with pain, varying from a feeling of discomfort in the
abdomen to marked tenderness. The tongue is furred, and usually there is
diarrhoea, while in the more severe attacks the onset is marked by chill
and a rise of temperature. An attack may last from one day to four days.
Treatment for mild cases is simply a dose of castor-oil (children) or blue
pill (adults), but in severe cases vomiting should be promoted by warm
water, or the stomach tube if necessary, and a dose of calomel (3 grains),
followed by salts, should be given. Absolute rest to the stomach is
necessary, and only small quantities of water allowed. Repeated attacks
lead to the establishment of the chronic form. _Chronic dyspepsia_ is a
condition of disturbed digestion due to the prolonged use of unsuitable, or
improperly prepared, foods. Hot cakes, excess of tea, coffee, or alcohol,
rapid and irregular meals are all common causes. It may also arise in the
course of diseases like anaemia, chronic tuberculosis, gout, Bright's
disease, chronic heart disease, cirrhosis, and in diseases of the stomach
itself, as cancer, gastric ulcer, and gastric dilatation. The most common
symptoms are a feeling of oppression after food, tenderness over the
stomach, headache, nausea, flatulence, constipation, and occasionally
vomiting. Treatment consists of dietetic measures, regulated exercises,
change of air and surroundings, and avoidance of depression. Milk should be
used freely, and in severe cases should be given alone till improvement
sets in. Fats and greasy dishes should be avoided. Fruits are sometimes
well borne, and at other times the reverse. Drugs do not play so important
a r[^o]le, but bitter tonics, like nux vomica, quassia, gentian, &c., are
the best. Constipation should be treated when necessary.
DYSPHO'NIA is difficulty in speaking, and is the result of some forms of
laryngitis. The condition is aggravated by attempts to use the voice, and
complete rest is necessary to bring about an early and satisfactory
recovery. Tonics, moderate exercise, and a holiday hasten recovery.
DYSPNOEA (dis-pn[=e]'a) is difficult or laboured breathing. It is a symptom
of diseases of the heart or lungs, and is produced by any condition which
interferes with normal respiration. It is sometimes present in nervous
disturbances.
DZE'REN, or DZE'RON, the Chinese antelope, a remarkably swift species of
antelope (_Procapra guttur[=o]sa_) inhabiting the dry arid deserts of
Central Asia, Tibet, China, and Southern Siberia. It is nearly 4-1/2 feet
in length, and 2-1/2 feet high at the shoulder.
DZIG'GETAI, or KIANG (_Equus hemi[)o]nus_), a species of wild ass native to
Central Asia, allied both to the horse and ass. Its head is large like that
of the ass, but in form resembles that of the horse. The ears also resemble
those of the horse. It runs with a rapidity exceeding that of the best
Arabian horses.
DZOUNGARIA, or SUNGARIA, a Chinese territory in Central Asia, stretching
from about 43deg to 48deg N. lat. and from about 82deg to 86deg E. long. It
has an area of 147,950 sq. miles, and pop. 600,000. It is administratively
connected with Kuldja, and since the surrender of Kuldja by the Russians in
1880 is again under Chinese rule. Dzoungaria, once the centre of an
independent empire, was first conquered by the Chinese in 1757.
* * * * *
E
E, the second vowel and the fifth letter of the English alphabet. It occurs
more frequently in English words than any other letter of the alphabet. Its
long or natural sound in English coincides with the sound of _i_ in the
Italian and French languages, as in _here_, _mere_, _me_. It has also
another principal sound, a short one, heard in _met_, _men_. It has besides
a sound like _a_ in _bare_, as in _there_, _where_, &c., and the obscure
sound which is heard in _her_. As a final letter in English it is generally
silent, but it serves to indicate that the preceding vowel is to have its
long sound, as in _mane_, _cane_, _plume_. When two _e_'s come together the
sound is generally the same as that of the single _e_ long, as in _deem_,
_esteem_, _need_ (compare, however, _pre-exist_, &c.).
E, in music, is the third note or degree of the diatonic scale, answering
to the _mi_ of the Italians and French.
EADIE ([=e]'di), John, D.D., a Scottish preacher and theologian, born 1810,
died 1876. He was educated at Glasgow University, and entered the ministry
of the Secession Church, becoming in 1843 professor of biblical literature
in the Divinity Hall of the Church, a post which he continued to hold after
the Secession body was merged in the United Presbyterian Church (in 1847).
Among his works are _Biblical Cyclopaedia_; _Analytical Concordance to the
Scriptures_; _Ecclesiastical Cyclopaedia_; _Commentary on the Greek Text of
Ephesians_, and similar works on _Colossians_, _Philippians_, and
_Galatians_; and _The English Bible_. He was one of the scholars engaged on
the Revised Version of the New Testament.
EAD'MER, an English monk, the friend and biographer of St. Anselm. In 1120
he was chosen Bishop of St. Andrews; but as the Scottish king refused to
recognize the right of the Archbishop of Canterbury to consecrate him, he
returned to England and died a simple monk about 1124. Besides the life of
St. Anselm, Eadmer wrote lives of St. Wilfrid, St. Dunstan, St. Odo, and
other English saints, as well as a valuable history (_Historiae Novorum_)
of events in England and the English Church from 1066 to 1122.
[Illustration: Imperial Eagle (_Aqu[)i]la mogilnik_)]
[Illustration: African Sea-eagle (_Halia[=e]tus vocifer_)]
EAGLE (Lat. _aquila_, Fr. _aigle_), the general name of raptorial birds
that form a group or sub-family (Aquil[=i]nae) of the great family
Falconidae, which includes the eagles, falcons, and hawks. The eagle is
popularly regarded as the noblest and most courageous of the rapacious
birds. It soars to a greater height than any other European bird, from
which circumstance the ancients considered it as the bird or messenger of
Jove. The genus Aqu[)i]la, which includes the most typical eagles, is
distinguished by its long and powerful bill, the curve commencing at the
cere, by its wings reaching to the tip of the tail, and by its tarsi being
feathered to the toes. The imperial eagle (_A. mogilnik_) of Central
Europe, North-East Africa, India, and China is probably the species to
which the popular belief in the courage, strength, and nobleness of eagles
is to be traced. _A. chrysaetus_, the golden eagle, is the chief British
species. It measures over 6 feet from tip to tip of the expanded wings, and
3 feet from the beak to the end of the tail. The adults have the body
brownish, becoming darker with age; the feathers of the head and neck
pointed, and of a golden-red hue. This species is found all over the
northern hemisphere. It was once common in the Highlands of Scotland, but
is now becoming rare. The Kirghis and other tribes of Central Asia use the
golden eagle to kill antelopes, foxes, and even wolves. Another British
eagle is the erne or sea-eagle (_Haliaetus albicilla_) found near the
sea-coast or lakes, and feeding largely on fish. The general colour is
greyish-brown, the head pale-coloured, the tail white. The bald eagle
(_Haliaetus leucoceph[)a]lus_), found in North America and North-East Asia,
is the symbol of the United States, though Franklin deplores the selection
on account of his mean and dishonest habit of robbing the industrious
osprey of the fish caught by him. Like all members of the genus, his diet
is less restricted than that of the true eagles; and he even takes carrion.
See also _Harpy Eagle_.
[Illustration: Roman Standard]
EAGLE, as a symbol. The eagle first appears as a war standard amongst the
Persians, through whom it reached the Egyptians. As the standard of the
Roman armies it was first used by Marius, and afterwards took the place of
all the other emblems at the head of the legions. It was first made of
wood, then of silver, and finally, under Caesar and his successors, of
gold. In the Mediaeval Ages the eagle became the heraldic emblem of the
Holy Roman Empire, and was made double-headed in the fourteenth century.
When the Holy Roman Empire fell to pieces in 1806, the double-headed eagle
was retained by Austria. The double-headed eagle was assumed by Tsar Ivan
III in 1472, and became the national military symbol of Russia; the
single-headed eagle was assumed by the modern German Empire in 1871, and by
the United States of America. The American eagle stands with outspread
wings guarding a shield, with the motto _E pluribus unum_. The eagle was
also the badge of several orders, the chief of which were the order of the
_Black Eagle_, founded by the Elector of Brandenburg in 1701, and the
highest order in Prussia; the order of the _Red Eagle_, also a Prussian
order, and founded in 1705; and the Russian order of the _White Eagle_,
originally Polish, and instituted in 1325.
EAGLE, a gold coin in the United States of the value of ten dollars, or L2
sterling, first coined in 1795. There are also half-eagles, quarter-eagles,
and double-eagles.
EAGLE-HAWK, a name sometimes applied to small South American eagles (genus
Morphnus), with short wings and long legs.
EAGLEHAWK, a gold-mining town in Victoria, Australia, 4 miles from Bendigo.
Pop. 8130.
EAGLE-OWL, a name for several large horned owls, such as _Bubo ignavus_
(the great horned owl), little inferior in size to the golden eagle, found
in many parts of Europe and sometimes in Britain. An allied species, the
Virginian horned owl (_B. virginianus_), is common in the United States.
EALING, a municipal and parliamentary borough of Middlesex, the former a
few miles west of London. Pop. 61,222.
[Illustration: Diagrammatic Section of Outer, Middle, and Inner Ear
P, Concha. E.C., External canal. D, Drum. H, Hammer. A, Anvil. E,
Eustachian tube. S. Stirrup, S.C, Semicircular canals. C, Cochlea. Arrows
denote the direction of vibration.]
EAR, the organ of hearing. In the higher vertebrates it is divided into the
outer, middle, and inner ear. The external ear, which is a cartilaginous
funnel for collecting the sound waves and directing them inwards, is
composed of the _concha_, or projecting part, and of the _auditory canal_,
which extends from the _concha_ to the membrane of the _tympanum_ or
_drum_. This membrane is a partition stretched obliquely across the bottom
of the auditory canal, which it separates from the middle ear or tympanum;
it is semi-transparent and very delicate. It vibrates with the waves of
sound which strike against it, and transmits the vibrations to certain
little bones of the cavity of the tympanum. These bones, which have been
named respectively the hammer (_malleus_), the anvil (_incus_), and the
stirrup (_stapes_), transmit the vibrations to the internal ear, forming a
chain communicating at one end with the membrane just mentioned, and at the
other with the inner ear. The internal ear consists of a complicated system
of tubes known as the _membranous labyrinth_, containing fluid in which
waves are set up by the vibrations transmitted to it by the little bones
from the drum membrane. The lower part of the labyrinth is coiled like a
snail shell, and is called the _cochlea_. It is the real organ of hearing.
The upper part consists of three _semicircular canals_, the function of
which is to record the position and movements of the body in space. The
middle ear communicates with the pharynx by the Eustachian tube, through
which air from the mouth may be introduced into the tympanic cavity, so as
to permit vibrations of the drum membrane. In the external auditory canal
of the ear is produced the cerumen or ear-wax. The cut shows P the concha,
E.C. the external canal, D the drum membrane partly removed, S the stirrup,
A the anvil and H the hammer, the small bones communicating with the drum
and vestibule, C cochlea, S.C semicircular canals, E Eustachian tube.--Cf.
Sir Thomas Wrightson, _An Enquiry into the Analytical Mechanism of the
Internal Ear_.
EAR-COCKLE, a disease in wheat caused by the presence in the grain of worms
belonging to the genus Vibrio. It is called in some parts of England
_purples_.
EARL (A.Sax. _eorl_; Dan. _jarl_), a degree of the British nobility between
marquess and viscount, the title of highest antiquity in England. The title
was made hereditary by William the Conqueror, and for a time was used
interchangeably with that of _count_, the corresponding title on the
Continent. The wife of an earl is still called a _countess_. The earl was
the highest in rank of the nobility until Edward III created a duke in
1357, and Richard II a marquess in 1385. The first earl of England is the
Earl of Arundel. An earl's coronet is composed of eight pearls raised upon
points, with small leaves between, above the rim. See _Peer_.
EARLE, John, English bishop and writer, born about 1601, died 1665. He was
educated at Oxford, and, after writing some short poems, gave to the world
anonymously in 1628 _Microcosmographie, or a Piece of the World discovered
in Essays and Characters_--a work full of wit, humour, and admirable
character-painting. He was tutor to Charles II, accompanied him during his
exile, and was held by him in the highest esteem. In 1662 he was
consecrated Bishop of Worcester, and next year was translated to Salisbury.