BORGIA, LUCREZIA BOULOGNE-SUR-SEINE
BORGLUM, SOLON HANNIBAL BOULTON, MATTHEW
BORGOGNONE, AMBROGIO BOUND
BORGO SAN DONNINO BOUNDS, BEATING THE
BORGU BOUNTY
BORIC ACID BOURBAKI, CHARLES DENIS SAUTER
BORING BOURBON
BORIS FEDOROVICH GODUNOV BOURBON, CHARLES
BORISOGLYEBSK BOURBON-LANCY
BORKU BOURBON L'ARCHAMBAULT
BORKUM BOURBONNE-LES-BAINS
BORLASE, WILLIAM BOURCHIER, ARTHUR
BORMIO BOURCHIER, THOMAS
BORN, IGNAZ BOURDALOUE, LOUIS
BORNA BOURDON, FRANCOIS LOUIS
BORNE, KARL LUDWIG BOURG-EN-BRESSE
BORNEO BOURGEOIS, LEON VICTOR AUGUSTE
BORNHOLM BOURGEOIS
BORNIER, HENRI BOURGES
BORNU BOURGET, PAUL CHARLES JOSEPH
BORODIN, ALEXANDER PORFYRIEVICH BOURIGNON, ANTOINETTE
BORODINO BOURKE
BOROLANITE BOURMONT, LOUIS AUGUSTE VICTOR
BORON BOURNE, VINCENT
BOROUGH, STEVEN BOURNE (town)
BOROUGH BOURNE (stream)
BOROUGHBRIDGE BOURNEMOUTH
BOROUGH ENGLISH BOURNONITE
BORROMEAN ISLANDS BOURREE
BORROMEO, CARLO BOURRIENNE, LOUIS ANTOINE FAUVELET DE
BORROMINI, FRANCESCO BOURRIT, MARC THEODORE
BORROW, GEORGE HENRY BOURSAULT, EDME
BORSIPPA BOURSE
BORT BOURSSE, ESAIAS
BORY DE SAINT-VINCENT, JEAN BOUSSINGAULT, JEAN BAPTISTE
BORZHOM BOUTERWEK, FRIEDRICH
BOS, LAMBERT BOUTHILLIER, CLAUDE
BOSA BOUTS-RIMES
BOSBOOM-TOUSSAINT, ANNA LOUISA BOUTWELL, GEORGE SEWALL
BOSC, LOUIS AUGUSTIN GUILLAUME BOUVARDIA
BOSCAN ALMOGAVER, JUAN BOUVET, FRANCOIS JOSEPH
BOSCASTLE BOUVIER, JOHN
BOSCAWEN, EDWARD BOUVINES
BOSCH, JEROM BOVEY BEDS
BOSCOVICH, ROGER JOSEPH BOVIANUM
BOSNIA AND HERZEGOVINA BOVIDAE
BOSPORUS BOVILL, SIR WILLIAM
BOSPORUS CIMMERIUS BOVILLAE
BOSQUET, PIERRE FRANCOIS JOSEPH BOW
BOSS BOWDICH, THOMAS EDWARD
BOSSI, GIUSEPPE BOWDITCH, NATHANIEL
BOSSU, RENE LE BOWDLER, THOMAS
BOSSUET, JAQUES BENIGNE BOWDOIN, JAMES
BOSTANAI BOWELL, SIR MACKENZIE
BOSTON, THOMAS BOWEN, CHARLES SYNGE CHRISTOPHER BOWEN
BOSTON (Lincolnshire, England) BOWEN, FRANCIS
BOSTON (Massachusetts, U.S.A.) BOWEN, SIR GEORGE FERGUSON
BOSTON (game of cards) BOWER, WALTER
BOSTONITE BOWERBANK, JAMES SCOTT
BOSTROM, CHRISTOFFER JACOB BOWIE, JAMES
BOSWELL, JAMES BOW-LEG
BOSWORTH, JOSEPH BOWLES, SAMUEL
BOTANY BOWLES, WILLIAM LISLE
BOTANY BAY BOWLINE
BOTHA, LOUIS BOWLING
BOTHNIA, GULF OF BOWLING GREEN (Kentucky, U.S.A.)
BOTHWELL, JAMES HEPBURN BOWLING GREEN (Ohio, U.S.A.)
BOTHWELL (town) BOWLS
BOTOCUDOS BOWNESS-ON-WINDERMERE
BOTORI BOWRING, SIR JOHN
BOTOSHANI BOWTELL
BO-TREE BOWYER, WILLIAM
BOTRYTIS BOX
BOTTA, CARLO GIUSEPPE GUGLIELMO BOXING
BOTTESINI, GIOVANNI BOXWOOD
BOTTICELLI, SANDRO BOYACA
BOTTIGER, KARL AUGUST BOYAR
BOTTLE BOY-BISHOP
BOTTLE-BRUSH PLANTS BOYCE, WILLIAM
BOTTLENOSE WHALE BOYCOTT
BOTTOMRY BOYD, ANDREW KENNEDY HUTCHISON
BOTZARIS, MARCO BOYD, ROBERT BOYD
BOTZEN BOYD, ZACHARY
BOUCHARDON, EDME BOYDELL, JOHN
BOUCHER, FRANCOIS BOYER, ALEXIS
BOUCHER, JONATHAN BOYER, JEAN PIERRE
BOUCHER DE CREVCOEUR, JACQUES BOYLE, JOHN J.
BOUCHES-DU-RHONE BOYLE, ROBERT
BOUCHOR, MAURICE BOYLE (town)
BOUCHOTTE, JEAN BAPTISTE NOEL BOYNE
BOUCICAULT, DION BOYS' BRIGADE
BOUCICAUT, JEAN BOZDAR
BOUDIN, EUGENE BOZRAH
BOUDINOT, ELIAS BRABANT (duchy)
BOUE, AMI BRABANT (Belgium)
BOUFFLERS, LOUIS FRANCOIS BRABANT, NORTH
BOUFFLERS, STANISLAS JEAN BRACCIANO
BOUGAINVILLE, LOUIS ANTOINE DE BRACCIOLINI, FRANCESCO
BOUGHTON, GEORGE HENRY BRACE, CHARLES LORING
BOUGIE BRACE, JULIA
BOUGUER, PIERRE BRACE
BOUGUEREAU, ADOLPHE WILLIAM BRACEGIRDLE, ANNE
BOUHOURS, DOMINIQUE BRACELET
BOUILHET, LOUIS HYACINTHE BRACHIOPODA
BOUILLE, FRANCOIS CLAUDE AMOUR BRACHISTOCHRONE
BOUILLON BRACHYCEPHALIC
BOUILLOTTE BRACKYLOGUS
BOUILLY, JEAN NICOLAS BRACKET
BOULAINVILLIERS, HENRI BRACKET-FUNGI
BOULANGER BRACKLESHAM BEDS
BOULANGER, GEORGE ERNEST BRACKLEY, THOMAS EGERTON
BOULAY DE LA MEURTHE, JOSEPH BRACKLEY
BOULDER (Colorado, U.S.A.) BRACQUEMOND, FELIX
BOULDER (large stone) BRACTON, HENRY DE
BOULDER CLAY BRADAWL
BOULE BRADDOCK, EDWARD
BOULEVARD BRADDOCK
BOULLE, ANDRE CHARLES BRADDON, MARY ELIZABETH
BOULOGNE BRADFORD, JOHN
BOULOGNE-SUR-MER
BORGIA, LUCREZIA (1480-1519), duchess of Ferrara, daughter of Cardinal
Rodrigo Borgia, afterwards Pope Alexander VI. (q.v.), by his mistress
Vanozza dei Cattanei, was born at Rome in 1480. Her early years were
spent at her mother's house near her father's splendid palace; but later
she was given over to the care of Adriana de Mila, a relation of
Cardinal Borgia and mother-in-law of Giulia Farnese, another of his
mistresses. Lucrezia was educated according to the usual curriculum of
Renaissance ladies of rank, and was taught languages, music, embroidery,
painting, &c.; she was famed for her beauty and charm, but the corrupt
court of Rome in which she was brought up was not conducive to a good
moral education. Her father at first contemplated a Spanish marriage for
her, and at the age of eleven she was betrothed to Don Cherubin de
Centelles, a Spanish nobleman. But the engagement was broken off almost
immediately, and Lucrezia was married by proxy to another Spaniard, Don
Gasparo de Procida, son of the count of Aversa. On the death of Innocent
VIII. (1492), Cardinal Borgia was elected pope as Alexander VI., and,
contemplating a yet more ambitious marriage for his daughter, he
annulled the union with Procida; in February 1493 Lucrezia was betrothed
to Giovanni Sforza, lord of Pesaro, with whose family Alexander was now
in close alliance. The wedding was celebrated in June; but when the
pope's policy changed and he became friendly to the king of Naples, the
enemy of the house of Sforza, he planned the subjugation of the vassal
lords of Romagna, and Giovanni, feeling his position insecure, left Rome
for Pesaro with his wife. By Christmas 1495 they were back in Rome; the
pope had all his children around him, and celebrated the carnival with a
series of magnificent festivities. But he decided that he had done with
Sforza, and annulled the marriage on the ground of the husband's
impotence (March 1497). In order to cement his alliance with Naples, he
married Lucrezia to Alphonso of Aragon, duke of Bisceglie, a handsome
youth of eighteen, related to the Neapolitan king. But he too realized
the fickleness of the Borgias' favour when Alexander backed up Louis
XII. of France in the latter's schemes for the conquest of Naples.
Bisceglie fled from Rome, fearing for his life, and the pope sent
Lucrezia to receive the homage of the city of Spoleto as governor. On
her return to Rome in 1499, her husband, who really loved her, was
induced to join her once more. A year later he was murdered by the order
of her brother Cesare. After the death of Bisceglie, Lucrezia retired to
Nepi, and then returned to Rome, where she acted for a time as regent
during Alexander's absence. The latter now was anxious for a union
between his daughter and Alphonso, son and heir to Ercole d'Este, duke
of Ferrara. The negotiations were somewhat difficult, as neither
Alphonso nor his father was anxious for a connexion with the house of
Borgia, and Lucrezia's own reputation was not unblemished. However, by
bribes and threats the opposition was overcome, and in September 1501
the marriage was celebrated by proxy with great magnificence in Rome. On
Lucrezia's arrival at Ferrara she won over her reluctant husband by her
youthful charm (she was only twenty-two), and from that time forth she
led a peaceful life, about which there was hardly a breath of scandal.
On the death of Ercole in 1505, her husband became duke, and she
gathered many learned men, poets and artists at her court, among whom
were Ariosto, Cardinal Bembo, Aldus Manutius the printer, and the
painters Titian and Dosso Dossi. She devoted herself to the education of
her children and to charitable works; the only tragedy connected with
this period of her life is the murder of Ercole Strozzi, who is said to
have admired her and fallen a victim to Alphonso's jealousy. She died on
the 24th of June 1519, leaving three sons and a daughter by the duke of
Ferrara, besides one son Rodrigo by the duke of Bisceglie, and possibly
another of doubtful paternity. She seems to have been a woman of very
mediocre talents, and only played a part in history because she was the
daughter of Alexander VI. and the sister of Cesare Borgia. While she was
in Rome she was probably no better and no worse than the women around
her, but there is no serious evidence for the charges of incest with her
father and brothers which were brought against her by the
scandal-mongers of the time.
See the bibliographies for ALEXANDER VI. and BORGIA, CESARE; and
especially F. Gregorovius's _Lucrezia Borgia_ (Stuttgart, 1874), the
standard work on the subject; also W. Gilbert's _Lucrezia Borgia,
Duchess of Ferrara_ (London, 1869), which, while containing much
information, is quite without historic value; and G. Campori's "Una
Vittima della Storia, Lucrezia Borgia," in the _Nuova Antologia_
(August 31, 1866), which aims at the rehabilitation of Lucrezia.
(L. V.*)
BORGLUM, SOLON HANNIBAL (1868- ), American sculptor, was born in
Ogden, Utah, on the 22nd of December 1868, the son of a Danish
wood-carver. He studied under Louis F. Rebisso in the Cincinnati art
school in 1895-1897, and under Fremiet in Paris. He took as his chief
subjects incidents of western life, cowboys and Indians, with which he
was familiar from his years on the ranch; notably "Lassoing Wild
Horses," "Stampeding Wild Horses," "Last Round-up," "On the Border of
White Man's Land," and "Burial on the Plains." His elder brother, Gutzon
Borglum (b. 1867), also showed himself an artist of some originality.
BORGOGNONE, AMBROGIO (fl. 1473-1524), Italian painter of the Milanese
school, whose real name was Ambrogio Stefani da Fossano, was
approximately contemporary with Leonardo da Vinci, but represented, at
least during a great part of his career, the tendencies of Lombard art
anterior to the arrival of that master--the tendencies which he had
adopted and perfected from the hands of his predecessors Foppa and
Zenale. We are not precisely informed of the dates either of the death
or the birth of Borgognone, who was born at Fossano in Piedmont, and
whose appellation was due to his artistic affiliation to the Burgundian
school. His fame is principally associated with that of one great
building, the Certosa, or church and convent of the Carthusians at
Pavia, for which he worked much and in many different ways. It is
certain, indeed, that there is no truth in the tradition which
represents him as having designed, in 1473, the celebrated facade of the
Certosa itself. His residence there appears to have been of eight years'
duration, from 1486, when he furnished the designs of the figures of the
virgin, saints and apostles for the choir-stalls, executed in _tarsia_
or inlaid wood work by Bartolommeo Pola, till 1494, when he returned to
Milan. Only one known picture, an altar-piece at the church San
Eustorgio, can with probability be assigned to a period of his career
earlier than 1486. For two years after his return to Milan he worked at
the church of San Satiro in that city. From 1497 he was engaged for some
time in decorating with paintings the church of the Incoronata in the
neighbouring town at Lodi. Our notices of him thenceforth are few and
far between. In 1508 he painted for a church in Bergamo; in 1512 his
signature appears in a public document of Milan; in 1524--and this is
our last authentic record--he painted a series of frescoes illustrating
the life of St Sisinius in the portico of San Simpliciano at Milan.
Without having produced any works of signal power or beauty, Borgognone
is a painter of marked individuality. He holds an interesting place in
the most interesting period of Italian art. The National Gallery,
London, has two fair examples of his work --the separate fragments of a
silk banner painted for the Certosa, and containing the heads of two
kneeling groups severally of men and women; and a large altar-piece of
the marriage of St Catherine, painted for the chapel of Rebecchino near
Pavia. But to judge of his real powers and peculiar ideals--his system
of faint and clear colouring, whether in fresco, tempera or oil; his
somewhat slender and pallid types, not without something that reminds us
of northern art in their Teutonic sentimentality as well as their
Teutonic fidelity of portraiture; the conflict of his instinctive love
of placidity and calm with a somewhat forced and borrowed energy in
figures where energy is demanded, his conservatism in the matter of
storied and minutely diversified backgrounds--to judge of these
qualities of the master as they are, it is necessary to study first the
great series of his frescoes and altar-pieces at the Certosa, and next
those remains of later frescoes and altar-pieces at Milan and Lodi, in
which we find the influence of Leonardo and of the new time mingling
with, but not expelling, his first predilections.
BORGO SAN DONNINO, a town and episcopal see of Emilia, Italy, in the
province of Parma, 14 m. N.W. by rail from the town of Parma. Pop. (1901)
town, 6251; commune, 12,109. It occupies the site of the ancient
Fidentia, on the Via Aemilia; no doubt, as its name shows, of Roman
origin. Here M. Lucullus defeated the democrats under Carbo in 82 B.C. It
was independent under Vespasian, but seems soon to have become a village
dependent on Parma. Its present name comes from the martyrdom of S.
Domninus under Maximian in A.D. 304. The cathedral, erected in honour of
this saint, is one of the finest and best-preserved Lombardo-Romanesque
churches of the 11th-13th centuries in north Italy. The upper part of the
facade is incomplete, but the lower, with its three portals and
sculptures, is very fine; the interior is simple and well-proportioned,
and has not been spoilt by restorations. For the _benitier_, a work of
the early 11th century, see _Rassegna d'Arte_, 1905, 180. Not far from
the town is the small church of S. Antonio del Viennese, a 13th-century
structure in brick (_ib_., 1906, 22). The Palazzo Comunale, in the
Gothic-Lombard style, is a work of the 14th century. Borgo S. Donnino is
an important centre for the produce and cattle of Emilia. (T. As.)
BORGU, or BARBA, an inland country of West Africa. The western part is
included in the French colony of Dahomey (q.v.); the eastern division
forms the Borgu province of the British protectorate of Nigeria. Borgu
is bounded N.E. and E. by the Niger, S. by the Yoruba country, N.W. by
Gurma. The country consists of an elevated plain traversed by rivers
draining north or east to the Niger. The water-parting between the Niger
basin and the coast streams of Dahomey and Lagos runs north-east and
south-west near the western frontier. In about 10 deg. N., below the
town of Bussa, rapids block the course of the Niger, navigable up to
that point from the sea. The soil is mostly fertile, and is fairly
cultivated, producing in abundance millet, yams, plantains and limes.
The acacia tree is common, and from it gum-arabic of good quality is
obtained. From the nut of the horse-radish tree ben oil is expressed.
Cattle are numerous and of excellent breed, and game is abundant. Borgu
is inhabited by a number of pagan negro tribes, several of whom were
dependent on the chief of Nikki, a town in the centre of the country,
the chief being spoken of as sultan of Borgu. The king of Bussa was
another more or less powerful potentate. In the early years of the 19th
century Borgu was invaded by the Fula (q.v.), but the Bariba (as the
people are called collectively) maintained their independence. In 1894
Borgu became the object of rivalry between France and England. The Royal
Niger Company, which had already concluded a treaty of protection with
the king of Bussa, sent out Captain (afterwards Sir) F.D. Lugard to
negotiate treaties with the king of Nikki and other chiefs, and Lugard
succeeded in doing so a few days before the arrival of French
expeditions from the west. Disregarding the British treaties, French
officers concluded others with various chiefs, invaded Bussa and
established themselves at various points on the Niger. To defend British
interests, the West African Frontier Force was raised locally under
Lugard's command, and a period of great tension ensued, British and
French troops facing one another at several places. A conflict was,
however, averted, and by the convention of June 1898 the western part of
Borgu was declared French and the eastern British, the French
withdrawing from all places on the lower Niger.
The British portion of Borgu has an area of about 12,000 sq. m. Up to
the period of inclusion within the protectorate of Nigeria little or
nothing was known of the country, though there were interesting legends
of the antiquity of its history. The population was entirely
independent, and resisted with success not only the Fula from the north
but also the armies of Dahomey and Mossi from the south and west.
Travellers who attempted to penetrate this country had never returned.
Since 1898 the country has been opened, and from being the most lawless
and truculent of people the Bariba have become singularly amenable and
law-abiding. Provincial courts are established, but there is little
crime in the province. The British garrisons have been replaced by civil
police. The assessment of taxes under British administration was
successfully carried out in 1904, and taxes are collected without
trouble. In south Borgu the people are agricultural but not industrious
or inclined for trade. In the north there are some pastoral settlements
of Fula. The Bariba themselves remain agricultural. Cart-roads have been
constructed between the town of Kiama and the Niger. The agricultural
resources of Borgu are great, and as the population increases with the
cessation of war and by immigration the country should show marked
development. Shea trees are abundant. Elephants are still to be found in
the fifty-mile strip of forest land which stretches between the Niger
and the interior of the province. The forest contains valuable sylvan
products, and there are great possibilities for the cultivation of
rubber. There are also extensive areas of fine land suitable for cotton,
with the waterway of the Niger close at hand. Labour might be brought
from Yorubaland close by, and a Yoruba colony has been experimentally
started. (See NIGERIA and BUSSA.)
BORIC ACID, or BORACIC ACID, H3BO3, an acid obtained by dissolving boron
trioxide in water. It was first prepared by Wilhelm Homberg (1652-1715)
from borax, by the action of mineral acids, and was given the name _sal
sedativum Hombergi_. The presence of boric acid or its salts has been
noted in sea-water, whilst it is also said to exist in plants and
especially in almost all fruits (A.H. Allen, _Analyst_, 1904, 301). The
free acid is found native in certain volcanic districts such as Tuscany,
the Lipari Islands and Nevada, issuing mixed with steam from fissures
in the ground; it is also found as a constituent of many minerals
(borax, boracite, boronatrocalcite and colemanite).
The chief source of boric acid for commercial purposes is the Maremma of
Tuscany, an extensive and desolate tract of country over which jets of
vapour and heated gases (_soffioni_) and springs of boiling water spurt
out from chasms and fissures. In some places the fissures open directly
into the air, but in other parts of the district they are covered by
small muddy lakes (_lagoni_). The soffioni contain a small quantity of
boric acid (usually less than 0.1%), together with a certain amount of
ammoniacal vapours. In order to obtain the acid, a series of basins is
constructed over the vents, and so arranged as to permit of the passage
of water through them by gravitation. Water is led into the highest
basin and by the action of the heated gases is soon brought into a state
of ebullition; after remaining in this basin for about a day, it is run
off into the second one and is treated there in a similar manner. The
operation is carried on through the entire series, until the liquor in
the last basin contains about 2% of boric acid. It is then run into
settling tanks, from which it next passes into the evaporating pans,
which are shallow lead-lined pans heated by the gases of the soffioni.
These pans are worked on a continuous system, the liquor in the first
being concentrated and run off into a second, and so on, until it is
sufficiently concentrated to crystallize. The crystals are purified by
recrystallization from water. Artificial soffioni are sometimes prepared
by boring through the rock until the fissures are reached, and the water
so obtained is occasionally sufficiently impregnated with boric acid to
be evaporated directly. Boric acid is also obtained from
boronatrocalcite by treatment with sulphuric acid, followed by the
evaporation of the solution so obtained. The residue is then heated in a
current of superheated steam, in which the boric acid volatilizes and
distils over. It may also be obtained by the decomposition of boracite
with hot hydrochloric acid. In small quantities, it may be prepared by
the addition of concentrated sulphuric acid to a cold saturated solution
of borax.
Na2B4O7 + H2SO4 + 5H2O = Na2SO4 + 4H3BO3.
Boric acid crystallizes from water in white nacreous laminae belonging
to the triclinic system; it is difficultly soluble in cold water, but
dissolves readily in hot water. It is one of the "weak" acids, its
dissociation constant being only 0.08169 (J. Walker, _Jour. of Chem.
Soc._, 1900, lxxvii. 5), and consequently its salts are appreciably
hydrolysed in aqueous solution. The free acid turns blue litmus to a
claret colour. Its action upon turmeric is characteristic; a turmeric
paper moistened with a solution of boric acid turns brown, the colour
becoming much darker as the paper dries; while the addition of sodium
or potassium hydroxide turns it almost black. Boric acid is easily
soluble in alcohol, and if the vapour of the solution be inflamed it
burns with a characteristic vivid green colour. The acid on being
heated to 100 deg. C. loses water and is converted into _metaboric
acid_, HBO3; at 140 deg. C., _pyroboric acid_, H2B4O7, is produced; at
still higher temperatures, boron trioxide is formed. The salts of the
normal or orthoboric acid in all probability do not exist; metaboric
acid, however, forms several well-defined salts which are readily
converted, even by carbon dioxide, into salts of pyroboric acid. That
orthoboric acid is a tribasic acid is shown by the formation of ethyl
orthoborate on esterification, the vapour density of which corresponds
to the molecular formula B(OC2H5)3; the molecular formula of the acid
must consequently be B(OH)3 or H3BO3. The metallic borates are
generally obtained in the hydrated condition, and with the exception
of those of the alkali metals, are insoluble in water. The most
important of the borates is sodium pyroborate or borax (q.v.).
Borax and boracic acid are feeble but useful antiseptics. Hence they
may be used to preserve food-substances, such as milk and butter (see
ADULTERATION). In medicine boracic acid is used in solution to relieve
itching, but its chief use is as a mild antiseptic to impregnate lint
or cotton-wool. Recent work has shown it is too feeble to be relied
upon alone, but where really efficient antiseptics, such as mercuric
chloride and iodide, and carbolic acid, have been already employed,
boracic acid (which, unlike these, is non-poisonous and non-irritant)
may legitimately be used to maintain the aseptic or non-bacterial
condition which they have obtained. Borax taken internally is of some
value in irritability of the bladder, but as a urinary antiseptic it
is now surpassed by several recently introduced drugs, such as
urotropine.
BORING. The operations of deep boring are resorted to for ascertaining
the nature, thickness and extent of the various geological formations
underlying the surface of the earth. Among the purposes for which boring
is specifically employed are: (1) prospecting or searching for mineral
deposits; (2) sinking petroleum, natural gas, artesian or salt wells;
(3) determining the depth below the surface of bed-rock or other firm
substratum, together with the character of the overlying materials,
preparatory to mining or civil engineering operations; (4) carrying on
geological or other scientific explorations.
Prospecting by boring is practised most successfully in the case of
mineral deposits of large area, which are nearly horizontal, or at least
not highly inclined; e.g. deposits of coal, iron, lead and salt. Wide,
flat beds of such minerals may be pierced at any desired number of
points. The depth at which each hole enters the deposit and the
thickness of the mineral itself are readily ascertained, so that a map
may be constructed with some degree of accuracy. Samples of the mineral
are also secured, furnishing data as to the value of the deposit. While
boring is sometimes adopted for prospecting irregular and steeply
inclined mineral deposits of small area, the results are obviously less
trustworthy than under the conditions named above, and may be actually
misleading unless a large number of holes are bored. Incidentally,
bore-holes supply information as to the character and depth of the
valueless depositions of earth or rock overlying the mineral deposit.
Such data assist in deciding upon the appropriate method for, and in
estimating the cost of, sinking shafts or driving tunnels for the
development and exploitation of the deposit. In sinking petroleum wells,
boring serves not only for discovering the oil-bearing strata but also
for extracting the oil. This industry has become of great importance in
many parts of the United States, in southern Russia and elsewhere. Rock
salt deposits are sometimes worked through bore-holes, by introducing
water and pumping out the solution of brine for further treatment. The
sinking of artesian wells is another application of boring. They are
often hundreds, and sometimes thousands, of feet in depth. A well in St
Louis, Missouri, has a depth of 3843 ft.
Boring is useful in mines themselves for a variety of purposes, such as
exploring the deposit ahead of the workings, searching for neighbouring
veins, and sounding the ground on approaching dangerous inundated
workings. In the coal regions of Pennsylvania, bore-holes are often sunk
for carrying steam pipes and hoisting ropes underground at points remote
from a shaft.
Several of the methods of boring in soft ground are employed in
connexion with civil engineering operations; as for ascertaining the
depth below the surface to solid rock, preparatory to excavating for and
designing deep foundations for heavy structures, and for estimating the
cost of large scale excavations in earth and rock.
Lastly, a number of deep holes have been bored for geological
exploration or for observing the increase of temperature in depth in the
earth's crust; for example, at Paruschowitz, Silesia, about 6700 ft.
deep; at Leipzig, Germany, 6265 ft.; near Pittsburg, Pennsylvania, 5532
ft.; and at Wheeling, West Virginia, nearly 5000 ft. The two last
mentioned were intended to obtain as complete a knowledge as possible of
the bituminous coal and oil-bearing formations.
There are five methods of boring, viz.: by (1) earth augers, (2) drive
pipes, (3) long, jointed rods and drop drill, (4) the rope system, in
which the rods are replaced by rope, (5) rotary drills. The first two
methods are adapted to soft or earthy soils only; the others are for
rock.
1. _Earth augers_ comprise spiral and pod augers. The ordinary spiral
auger resembles the wood auger commonly used by carpenters. It is
attached to the rod or stem by a socket joint, successive sections of
rod being added as the hole is deepened. The auger is rotated by means
of horizontal levers, clamped to the rod--by hand for holes of small
diameter (2 to 6 in.), the larger sizes (8 to 16 in.) by horse power.
Clayey, cohesive soils, containing few stones, are readily bored;
stony ground with difficulty. The operation of the auger is
intermittent. After a few revolutions it is raised and emptied, the
soil clinging between the spirals. Depths to 50 or 60 ft. are usually
bored by hand; deeper holes by horse power. For sandy, non-cohesive
soils, the auger may be encircled by a close-fitting sheet-iron
cylinder to prevent the soil from falling out.
Pod augers generally vary in diameter from 8 to 20 in. A common form
(fig. l) consists of two curved iron plates, one attached to the rod
rigidly, the other by hinge and key. By being turned through a few
revolutions the pod is filled, and is then raised and emptied. For
boring in sandy soils, the open sides are closed by hinged plates.
Fig. 2 shows another type of pod auger. For holes of large diameter
earth augers are handled with the aid of a light derrick.
[Illustration: FIG. 1. FIG. 2. Pod Auger.]
2. _Drive pipes_ are widely used, both for testing the depth and
character of soft material overlying solid rock and as a necessary
preliminary to rock boring, when some thickness of surface soil must
first be passed through. In its simplest form the drive pipe consists
of one or more lengths of wrought iron pipe, open at both ends and
from 1/2 in. to 6 in. diameter. When of small size the pipe is driven
by a heavy hammer; for deep and large holes, a light pile-driver
becomes necessary. The lower end of the pipe is provided with an
annular steel shoe; the upper end has a drivehead for receiving the
blows of the hammer. Successive lengths are screwed on as required.
For shallow holes the pipe is cleaned out by a "bailer" or
"sand-pump"--a cylinder 4 to 6 ft. long, with a valve in the lower
end. It is lowered at intervals, filled by being dashed up and down,
and then raised and emptied. If, after reaching some depth, the
external frictional resistance prevents the pipe from sinking farther,
another pipe of small diameter may be inserted and the driving
continued. Drive pipes are often sunk by applying weights at the
surface and slowly rotating by a lever. Two pipes are then used, one
inside the other. Water is pumped down the inner pipe, thus loosening
the soil, raising the debris and increasing the speed of driving. The
"driven well" for water supply is an adaptation of the drive pipe and
put down in the same way.
[Illustration: FIG. 3. Drill Bit.]
[Illustration: FIG. 4. Rod Joint.]
3. _Drill and Rods._--This method has long been used in Europe and
elsewhere for deep boring. In the United States it is rarely employed
for depths greater than 200 or 300 ft. The usual form of cutting tool
or drill is shown in fig. 3. The iron rods are from 1 to 2 in. square,
in long lengths with screw joints (fig. 4). Wooden rods are
occasionally used. For shallow holes (50 to 75 ft.) the work is done
by hand, one or two cross-bars being clamped to the rod. The men
alternately raise and drop the drill, meanwhile slowly walking around
and around to rotate the bit and so keep the hole true. The cuttings
are cleaned out by a bailer, as for drive pipes.
In boring by hand, the practical limit of depth is soon reached, on
account of the increasing weight of the rods. For going deeper a
"spring-pole" may be used. This is a tapering pole, say 30 ft. long
and 5 or 6 in. diameter at the small end. It rests in an inclined
position on a fulcrum set about 10 ft. from the butt, the latter being
firmly fixed. The rods are suspended from the end of the pole, which
extends at a height of several feet over the mouth of the hole. With
the aid of the spring of the pole the strokes are produced by a slight
effort on the part of the driller. Average speeds of 6 to 10 ft. per
10 hours are easily made, to depths of 200 to 250 ft.
[Illustration: FIG. 5. Sliding Link.]
For deep boring the rod system requires a more elaborate plant. The
rods are suspended from a heavy "walking beam" or lever, usually
oscillated by a steam engine. By means of a screw-feed device, the
rods, which are rotated slightly after every stroke, are gradually fed
down as the hole is deepened, length after length being added. A tall
derrick carries the sheaves and ropes by which the rods and tools are
manipulated. The drill bit cannot be attached rigidly to the rods as
in shallow boring, because the momentum of the heavy moving parts,
transmitted directly to the bit as the blow is struck, would cause
excessive vibration and breakage. It becomes necessary, therefore, to
introduce a sliding-link joint between the rods and bit. One form of
link is shown in fig. 5. On striking its blow, the bit comes to rest,
while the rods continue to descend to the end of the stroke, the upper
member of the link sliding down upon the lower. Then, on the up stroke
the lower link, with the bit, is raised for delivering another blow.
For large holes the striking weight is, say, 800 to 1000 lb., length
of stroke 2-1/2 to 5 ft., and speed from 20 to 30 strokes per minute.
[Illustration: FIG. 6. Kind Free-Falling Tool.]
By using the sliding link the cross-section and weight of the rods may
be greatly reduced, the only strain being that of tension. To deliver
a sharp, effective blow, however, the rods must drop with a quick
stroke, which brings a heavy strain upon the operating machinery. For
overcoming this difficulty, various "free-falling tools" have been
devised. By these the bit is allowed to fall by gravity; the rod
follows on its measured down stroke, and picks up the bit.
Free-falling tools are of two classes: (1) those by which the bit is
released automatically; (2) those operated by a sudden twist imparted
to the rod by the drillman. One of the best known of the first class
is the Kind free-fall (fig. 6). The shank of the bit is gripped and
released by the jaws J, J, worked through a toggle joint by movements
of the disk D. When the rod begins its downward stroke, the resistance
of the water in the hole slightly raises D, thus opening the jaws and
releasing the bit, which falls by gravity. On reaching the end of the
stroke the jaws again catch the shank of the bit and raise it for
delivering another blow. The Fabian free-fall may be noted as an
example of the second class (see Kohler, _Lehrbuch der Bergbaukunde_,
p. 57). Tools are sometimes used for cutting an annular groove in the
bottom of the hole, and raising to the surface the core so formed, for
observing the character of the rock.
4. _Rope and Drop Tools._--This method was long ago used in China.
Because of its extensive application in the oil-fields it is generally
designated in the United States as the "oil-well system." In its
various modifications it is often employed also in general prospecting
of mineral deposits and in sinking artesian, natural gas and salt
wells. One of its forms is known in England as the Mather & Platt
system.
The chief point of difference from rod-boring is the substitution of
rope for the jointed rods. For deep boring it possesses the advantage
of saving the large amount of time consumed in raising and lowering
the rods, as required whenever the hole is to be cleaned out, or a
dull bit replaced, since the tools are rapidly run up or down by means
of the rope with which they are operated while drilling. The speed of
rope-boring is therefore but little affected by increase of depth,
while with rod-boring it falls off rapidly. In its simplest form the
so-called "string of tools," suspended from the rope, is composed of
the bit or drill, jars and rope-socket. The jars are a pair of sliding
links, similar to those used for rod-boring, but serving a different
purpose, viz. to produce a sharp shock on the upward stroke, as the
jars come together, for loosening the bit should it tend to stick fast
in the hole. A heavy bar (auger stem) is generally inserted between
the jars and bit, for increasing the force of the blow. The weight of
another bar above the jars (sinker-bar) keeps the rope taut. The
length of stroke and feed are regulated by the "temper-screw" (fig.
7), a feed device resembling that used for rod-boring. Clamped to it
is the drill rope, which is let out at intervals, as the hole is
deepened. The bits usually range from 3 to 8 in. diameter, the speed
of boring being generally between 20 and 40 ft. per 24 hours,
according to the kind of rock. A great variety of special "fishing
tools" are made, for use in case of breakage of parts in the hole or
other accident.
[Illustration: FIG. 7. Temper Screw.]
5. _Diamond Drill._--The methods described above are capable of boring
holes vertically downward only. By the diamond drill, holes can be
bored in any direction, from vertically downward to vertically upward.
It has the further advantage of making an annular hole from which is
obtained a core, furnishing a practically complete cross-section of
the strata penetrated; the thickness and character of each stratum are
shown, together with its depth below the surface. Thus, the diamond
drill is peculiarly well adapted for prospecting mineral deposits from
which samples are desired. The first practical application of diamonds
for drilling in rock was made in 1863 by Professor Rudolph Leschot, a
civil engineer of Paris.
The apparatus consists essentially of a line of hollow rods, coupled
by screw joints, an annular steel bit or crown, set with diamonds,
being attached to the lower end. By means of a small engine on the
surface the rods are rapidly rotated and fed down automatically as the
hole deepened. The speed of rotation is from 300 to 800 revolutions
per minute, depending on the character of the rock and diameter of the
bit. While boring a stream of water is forced down the hollow rods by
a pump, passing back to the surface through the annular space between
the rods and the walls of the drill hole. The cuttings are thus
carried to the surface, leaving the bottom of the hole clean and
unobstructed. For recovering the core and inspecting the bit and
diamonds, the rods are raised at every 3 to 8 ft. of depth. This is
done by a small drum and rope, operated by the driving engine.
[Illustration: FIG. 8.--Little Champion Rock Drill.]
[Illustration: FIG. 9.]
Diamond drills of standard designs (fig. 8) bore holes from 1-9/16 to
2-3/4 in. diameter, yielding cores of 1 to 1-15/16 in. diameter, and
are capable of reaching depths of a few hundred to 4000 ft. or more.
They require from 8 to 30 boiler horse-power. Large machines will bore
shallower holes up to 6, 9 or even 12 in. diameter. For operating in
underground workings of mines, small and compact machines are
sometimes mounted on columns (fig. 9). They bore 1-1/4 to 1-9/16 in.
holes to depths of 300 to 400 ft., cores being 7/8 to 1 in. diameter.
Hand-power drills are also built. In the South African goldfields
several diamond drill holes from 4500 to 5200 ft. deep have been
successfully bored. Rates of advance for core-drilling to moderate
depths range usually from 2 to 3 ft. per hour, including ordinary
delays, though in favourable rock much higher speeds are often
attained. In deep holes the speeds diminish, because of time consumed
in raising and lowering the rods. If no core is desired a "solid bit"
is used. The drilling then proceeds faster, as it is only necessary to
raise the rods occasionally, for examining the condition of the bit.
[Illustration: FIG. 10. Diamond Drill Bit.]
The driving engine has two inclined cylinders, coupled to a
crank-shaft, by which, through gearing, the drill-rod is rotated. The
rods are wrought iron or steel tubes, in 5 to 10 ft. lengths. For
producing the feed two devices are employed, the differential screw
and hydraulic cylinder. For the _differential feed_ (fig. 9) the
engine has a hollow left-hand threaded screw-shaft, to which the rods
are coupled. This shaft is driven by a spline and bevel gearing and is
supported by a threaded feed-nut, carried in the lower bearing. Geared
to the screw-shaft is a light counter-shaft. By properly proportioning
the number of teeth in the system of gear-wheels, the feed-nut is
caused to revolve a little faster than the screw-shaft, so that the
drill-rod is fed downward a small fraction of an inch for each
revolution. To vary the rate of feed, as suitable for different rocks,
three pairs of gears with different ratios of teeth are provided. The
screw-shaft and gearing are carried by a swivel-head, which can be
rotated in a vertical plane, for boring holes at an angle.
[Illustration: FIG. 11. Core Lifter and Barrel.]
The _hydraulic feed_ is an improvement on the above, in that the rate
of feed is independent of the rotative speed of the rods and can be
adjusted with the utmost nicety. There are either one or two feed
cylinders, supplied with water from the pump. The rod, while rotating
freely, is supported by the feed cylinder piston and caused to move
slowly downward by allowing the water to pass from the lower to the
upper part of the cylinder. A valve regulates the passage of the water
and hence the rate of feed.
The bit (fig. 10 and fig. 11, B) is of soft steel, set with six to
eight or more diamonds according to its diameter. The diamonds,
usually from 1-1/2 to 2-1/2 carats in size, are carefully set in the
bit, projecting but slightly from its surface. Two kinds of diamonds
are used, "carbons" and "borts." The carbons are opaque, dark in
colour, tougher than the brilliant, and have no cleavage planes. They
are therefore suitable for drilling in hard rock. Borts are rough,
imperfect brilliants, and are best used for the softer rocks. As the
bit wears, the stones must be reset from time to time. The wear of
carbons in a well-set bit is small, though extremely variable. Above
the bit are the core-lifter and core-barrel. The core-lifter (fig. 11,
A) is a device for gripping and breaking off the core and raising it
to the surface. The barrel, 3 to 10 ft. long, fits closely in the hole
and is often spirally grooved for the passage of the water and debris.
It serves partly as a guide, tending to keep the hole straight, partly
for holding and protecting the core.
Diamond drills do not work satisfactorily in broken, fissured rock, as
the carbons are liable to be injured, loosened or torn from their
settings. In these circumstances, and for soft rocks, the diamond bit
may be replaced by a steel toothed bit. Another apparatus for
core-drilling is the Davis Calyx drill. For hard rock it has an
annular bit, accompanied by a quantity of chilled steel shot; for soft
rock, a toothed bit is used.
Diamond drill holes are rarely straight, and usually deviate
considerably from the direction in which they are started. Very deep
holes have been found to vary as much as 45 deg. and even 60 deg. from
their true direction. This is due to the fact that the rods do not fit
closely in the hole and therefore bend. It is also likely to occur in
drilling through inclined strata, specially when of different degrees
of hardness. By using a long and closely fitting core-barrel the
liability to deviation is reduced, but cannot be wholly prevented.
Holes which are nearly horizontal always deflect upward, because the
sag of the rods tilts up the bit. Diamond drill holes should therefore
always be surveyed. This is done by lowering into the hole instruments
for observing at a number of successive points the direction and
degree of deviation.[1] If accurately surveyed a crooked hole may be
quite as useful as a straight one.
AUTHORITIES.--For further information on boring see _Trans. Amer.
Inst. Mining Engs._ vol. ii. p. 241, vol. xxvii. p. 123; C. le Neve
Foster, _Text-book of Ore and Stone Mining_, chap. iii.; _Gluckauf_,
9th December 1899, 20th and 27th May 1905; _Scientific American_, 21st
August 1886; _Engineering and Mining Jour._ vol. lviii. p. 268, vol.
lxx. p. 699, vol. lxxx. p. 920; _Trans. Inst. Mining Engs._, England,
vol. xxiii. p. 685; _School of Mines Quarterly_, N. Y., vol. xvi. p.
1; _Zeitschr. fur Berg- Hutten- und Salinenwesen_, vol. xxv. p. 29;
Denny, "Diamond Drilling," _Mines and Minerals_, vol. xx., August
1899, p. 7, to January 1900, p. 241; _Mining Jour._, 26th January
1901; _Mining and Scientific Press_, 28th November 1903, p. 353; _Ost.
Zeitschr. fur Berg- und Huttenwesen_, 21st May, 4th June 1904; _Trans.
Inst. Mining and Metallurgy_, vol. xii. p. 301; _Engineering
Magazine_, March 1896, p. 1075. (R. P.*)