Chapter XVI: Appendix: II

STEEP ROMAN BRIDGES

Young pontists are always eager to know whether the Romans built gabled bridges, setting an example both to the East and to the West. On this topic there is little evidence, for most of the Roman bridges were built of timber. At Rimini, in the famous bridge of Augustus, there is an ascent at each end over the abutment, and at Alcantarilla, near Utrera, in Andalusia, the Roman bridge may be described as hog-backed. It crosses the Salado, a tributary of the Guadalquivir. Recently Mr. Edgar Wigram visited Alcantarilla, and he writes to me as follows:--

“The Roman bridge there is most interesting, almost untouched by restoration, yet it remains serviceable. It is a hog-backed structure of two arches, each about thirty-five feet in span; the width between the parapets may be fifteen feet, but a swarm of bees happened to be merry on the bridge, so I did not try to take accurate measurements. The voussoirs and spandrils are of stone with hammer-dressed faces, while the soffits are formed with wedge-shaped blocks of concrete, and a certain amount of brick is found in the piers. Along the river on one side are remains of an embankment. A tower stands at one end of the bridge, placed centrally to it, so the road has to make a double turn to pass. One wall of the tower is destroyed, but the other three are still about half their original height. The lower courses are of big stone blocks, while the upper part of the faces are filled in with ‘tapia’ concrete; the angles (or at least the two which still remain intact) are grooved with a queer circular recess some twelve inches in diameter. What purpose these grooves can have served I do not know. They look as if they may have been intended to accommodate the hinge-posts of gates; but a gate hung in them would hardly swing through ninety degrees. If a second tower ever existed, its foundations do not appear above ground-level. At Córdova there is only one tower, and it stands in a very similar position. By analogy, then, we may suppose that a second tower was not built at Alcantarilla; yet the grooved angles seem to require a corresponding tower with corresponding grooves, if gates were ever swung from them. Perhaps the grooves formed pivots for some sort of defensive engine, such as the ‘iron hand’ of Archimedes, which seems to have been some sort of great grappling crane. The angles of a tower would be fit places to plant a weapon of this description; but we need help from an expert in ancient military engineering.”

INDEX AND GLOSSARY

INDEX AND GLOSSARY

ABBAS II, Shah of Persia, 1641-66;
the Pul-i-Khaju at Isfahan dates from his time, 215.

ABBOT’S BRIDGE, Bury St. Edmunds, its ecclesiastical workmanship and
its double ring of voussoirs, 305 _footnote_.

ABERYSTWYTH, South Wales, the Devil’s Bridge at, over the Afon
Mynach, its old legend, 66, 67, 68.

ABINGDON BRIDGE, Ballad of, by Richard Fannande Iremonger, dated
1458, its value to pontists, 208, 251-2.

ABUTMENT PIERS, these are so strong that they act as abutments,
and hence the loss of one arch does not overthrow another by
withdrawing a counterbalancing thrust from one side of a
pier. Perronet says: “The piers of bridges ought to be
considered either as performing the duty of abutments, or as
relieved of this duty by the counteraction of the collateral
arches, through which the thrust is carried from abutment to
abutment of the bridge. In the first case, piers should
resist lateral pressure as capably as the abutments
themselves, that they may withstand the side thrust of the
arch-stones which tends to overturn them, and which increases
by so much the more as the arches are flatter and the piers
loftier. In the second case, the piers must have substance
enough to carry the weight of the two half arches raised upon
the two sides of each pier respectively,” together with those
parts of the upper works that lie over each pier. Roman piers
are abutments also, as a rule, their thickness ranging from a
half to a third of the spaces between them; the effect of
this great bulk both on the current of rivers and on Roman
bridge-building is described on page 284. A great many
bridges of the Middle Ages had abutment piers, but in many
cases they were dams rather than bridges; the piers occupied
far too much space in the waterways and caused terrible
floods like those that happened at Lyons in the winter of
1839-40. Old London Bridge was a perforated dam (p. 220); and
after her removal in 1831-2, an improvement was noted in the
drainage, and consequently in the healthiness, of all the
lower parts of London above bridge. So abutment piers, when
they are either too thick or too numerous, are social evils.
This fact was recognised by bridgemen at the beginning of the
sixteenth century, when some diminution took place in the
relative proportion of the piers of bridges to the spans of
arches; and little by little a new routine came into vogue
and displaced the abutment pier from all service. Here was
another social evil, for long arched bridges with no abutment
piers were unmilitary, and therefore at odds with the
strategy of national defence. Not an arch could be cut
without endangering its neighbouring arches. Gabriel and
Perronet, after considering this fact, wished abutment piers
to be revived in a discreetly effective manner (_footnote_ p.
338), but their excellent advice was not followed.
Defenceless bridges became fashionable everywhere, though
they added innumerable anxieties to the perils of military
war. The Valentré Bridge at Cahors should be studied as the
best example of a mediæval battle-bridge, but the abutment
piers might have been improved, 283-4. To-day a new era in
bridge-building is heralded by rapid improvements in airships
and aeroplanes; there should be a congress of architects and
engineers to discuss the urgent questions of national defence
that the piers and footways of bridges bring before our
common sense, 335, 358.

ABUTMENTS, the end supports of a bridge.

ABYDOS, one of the most ancient cities of Upper Egypt;
an early arch there in the temple of Rameses II, 155.

ACARNANIA, the most westerly province of ancient Greece;
early examples of the semicircular arch, 160.

ACCIDENTS, THE, OF CIVILIZATION, they claim as many lives in a
century as do the casualties on stricken fields, 34 _footnote_.

ACCIDENTS TO OLD LONDON BRIDGE, 218.

ADAM OF EVOLUTION, THE, had sense enough probably to lay a flat
stone from bank to bank of a deep rivulet, 60;
his personal appearance, 115-16;
his character, 116, 117;
his attitude to tree-bridges, 116;
and to several other bridges made by Nature, 118-19.

ADDY, SIDNEY O., his book on “The Evolution of the English House,”
139 _footnote_.

ADRIAN IV, Pope, sanctioned in 1156 the building of a chapel on the
Roman bridge over the Vidourle at Pont Ambroise in France, 82.

ÆLIUS, PONS, built by Hadrian in A.D. 13, 194, 324.

AEROPLANES, in their relation to bridge-building and national
defence, vii, viii, 59, 335, 358.

AFRICAN NATIVES, their tree-bridges and their want of initiative,
123, 148.

AFON MYNACH, the cataract in South Wales, 67.

AGOWE DISTRICT, Equatorial Central Africa, a primitive suspension
bridge partly made with very thick vines, 148.

AGRIPPA, son-in-law of Augustus Cæsar, the reputed founder of the
Pont du Gard, about 19 years B.C., 174.

AIRMEN SCOUTS, their relations to future wars, 335, 358.

AIRSHIPS, their influence on bridge-building and on national defence,
vii, viii, 59, 335, 358.

AIRVAULT, DEUX-SÈVRES, Le Pont de Vernay, a famous bridge with ribbed
arches, French Romanesque Period, Twelfth Century;
See the colour plate facing page 96;
and the remarks on ribbed arches, 93-100.

ALAMERI, HALAF, a famous bridge-builder in Spain, 286-7.

ALBARRACIN, in Aragon, its timber bridge with stone piers, 275.

ALBI BRIDGE over the Tarn, famous in the history of pointed arches,
84, 86, 89, 90, 91, 92;
See also the illustrations facing pages 72 and 92.

ALBI, Railway Bridge at, see the colour plate facing page 8.

ALCÁNTARA, in Spain, and the Puente Trajan over the Tagus;
a wonderful Roman bridge, 6, 16, 153, 183 _et seq._, 212, 321.

ALCÁNTARA at Toledo, a famous old war-bridge, 285-7;
and see the two colour prints facing pages 32 and 284.

ALCANTARILLA, in Spain, its most interesting Roman war-bridge, 30,
182, and 367-8.

ALDEGUELA, JOSÉ MARTIN, a great Spanish bridge-builder of the 18th
century, 280 _footnote_.

ALDERSHOT, its vulnerable bridges on a single-line railway that runs
toward Southampton, 336 _footnote_.

ALEXANDER THE GREAT, his possible influence on bridge-building in
India, 272.

ALEXANDRINE AQUEDUCT, the decoration of its wall surfaces with
coloured tufa arranged in geometrical patterns, 190.

ALGERIA, Pont Sidi Rached at Constantine, built between 1908 and
1912, 53.

ALI VERDI KHAN, the Bridge of, at Isfahan in Persia, over the
Zendeh Rud, 212, 268-70.

ALLBUTT, SIR CLIFFORD, on the immaturity of modern science, 7.

ALLEN’S “History of the County of York,” 243 _footnote_.

ALONSO OF SPAIN, in 1258, repaired the Alcántara at Toledo, 287.

ALTAMIRA CAVERN, near Santander, its prehistoric art relics, 62.

AMBROISE, PONT, over the Vidourle, a Roman bridge, now a ruin, 82,
177.

AMERICA, SOUTH, primitive bridges there, as described by Don Antonio
de Ulloa, 135, 146-7.

AMERICA, UNITED STATES OF, their timber bridges, 142-3;
their defenceless modern bridges, 352-4.

AMMANATI, BARTOLOMEO, Florentine architect of the 16th century, his
great bridge over the Arno, 222, 316-17.

AMSTERDAM, the Hoogesluis at, a strumpet of a bridge, 323.

ANGERS, a suspension bridge at, how it gave way when soldiers were
passing across it, 144 _footnote_.

ANCHORAGE OF CHAIN BRIDGES, at Auhsien in China, 346-7.

ANCUS MARCIUS, and the Pons Sublicius, 64, 140.

ANGELL, NORMAN, a firm believer in the illusion called peace, 351.

ANGELO, PONTE SANT’, at Rome, anciently the Pons Ælius, 194, 324.

ANIO VETUS, Roman Aqueduct, its great height, 190.

ANTIQUARIES, their aloofness from public interests, 9, 11;
very often they mistake facts for truths, 9-11;
their pedantry and its results, 11;
their attitude to the Clapper Bridges over Dartmoor rivers, 100,
102, 103.

ANTIQUARY, an old, his bad advice to young pontists, 8-10.

ANTONIO DA PONTE, in 1588, began to erect the Rialto, 212.

ANTS, their intelligence, 110;
they bore tunnels under water and make bridges over running
streams, 122;
the fertility of their minute cerebral ganglia contrasted with the
dullness of the average human brain, 239-40.

APATHY, BRITISH, in matters of national defence, 15, 16, 33
_footnote_, 336 _footnote_, 350, 351, 355, 359, 360.

APOLLODORUS OF DAMASCUS, great Roman bridge-builder, 129-30, 131, 344.

APPENZELL, Canton of, the birthplace of Ulric and Jean Grubenmann,
141.

AQUEDUCTS, ROMAN, the Pont du Gard, 83, 167-75, 321;
at Lyon, 176, 213;
at Luynes and Fréjus, 176;
the Marcian Aqueduct, 189 _footnote_;
Nero’s Aqueduct, 189;
the Alexandrine, 190;
Anio Vetus, 190;
at Minturnæ, 190;
Tarragona, 189;
Segóvia, 183-4, 189, 190;
see also the illustration facing page 184;
Smyrna, 165;
number of aqueducts at Rome in the sixth century A.D., 189
_footnote_;
Sextus Julius Frontinus, Superintendent of the Aqueducts at Rome,
wrote, in the first century of our Era, a treatise on Roman
aqueducts, 189 _footnote_.

AQUITAINE, DUKE OF, William the Great, his attitude to the collection
of tolls on bridges, 240.

ARABIAN ARCHES, their shapes are of three sorts, the horseshoe, the
semicircular, and the pointed. Often they are enriched by a
sort of feathering or foliation around the arch, and this
ornament is closely akin to Gothic work, which it preceded by
a considerable time. The Arabian style, known also as
Saracenic and Moorish, is a fanciful composition in which
details from Egypt and Greece and Rome are alembicated with
“the light fantastic lattice-work of the Persians.” To-day we
find its graceful influence in the greatest bridges at
Isfahan, 213, and also in much Spanish work, 28-9, 285-6,
288. Some writers believe that pointed arches were invented
by the Arabs, yet they were built in Egypt during the Fourth
Dynasty, 155-6, and also by the Babylonians, 275 _footnote_.
The Saracenic pointed arch was a forerunner of the Gothic
pointed style, and it became familiar to the Crusaders,
86-93; but we must draw a wide distinction between the
pointed arch and the pointed Gothic style. Arabian architects
did not achieve an upward flight and rhythm akin to the
vertical principle of inspired Gothic; their buildings
preserved the horizontal line which gave and gives character
to classical traditions, 152, 153, 336. If, then, the pointed
arch in Europe was borrowed from Arabian architects, as many
antiquaries believe, 88, it passed through a great
transformation in technical sentiment, and became an original
inspiration.

ARAGON, 275.

ARCADES cut transversely through the piers of the ruined Roman
aqueduct at Lyon, 213;
and also in the two greatest bridges at Isfahan, 214, 215, 270.

ARCADES, COVERED, in the best bridges at Isfahan, pierced through the
outer walls from one end to the other, 214, 215, 269.

ARC DE ST. BÉNÉZET, in the Bridge of Avignon, 81;
its elliptical shape had a forerunner in the vault of Chosroes’
great hall at Selucia-Ctesiphon, which may have been derived
from Babylonian tradition, 275 _footnote_;
there is even a Roman starting-point for Bénézet’s arch, 196.

ARC DE TRIOMPHE, Chinese, 315;
Roman, 176-7, 183.

ARCHÆOLOGY, PREHISTORIC, why it is tiresome to most people, 119-20.

ARCHERY, EARLY ENGLISH, the Conscription of, how its legal statutes
were imperilled by trade “rings,” 49;
some Elizabethans wanted to see a revival of the archery statutes,
333.

ARCHES made by Nature, the Pont d’Arc at Ardèche, 6, 88, 150;
the Rock Bridge in Virginia, 6;
the Durdle Door at Lulworth, 151;
La Roche Percée at Biarritz, 151;
La Roche Trouée, near Saint-Gilles Croix-de-Vie, 151;
at Icononzo, in New Grenada, 151;
Lydstep Arch on the coast of Pembroke, 150 _footnote_;
on the formation of natural arches, 151-2;
how these arches were copied by mankind, 6, 153, 154, 155, 156, 157;
their significance, 152-4.

ARCHES made by Man, those copied or adapted from Nature’s models, 6,
153-7;
their significance, 152-4;
the symbolism of arches, 154;
arches in art are more suggestive than circles, 154-5;
in some arches the vaults are built with parallel bands of stone,
Roman examples, 82, 83, 174;
mediæval example, 81, 82, 83;
arches made with criss-cross piers of timber, Gaulish, 70, 71;
in Kashmír, 71, 72, 73;
in North Russia, 73;
cycloid arches, in Ammanati’s bridge, 222, 316-17;
elliptical arches, St. Bénézet’s, 81;
in Chosroes’ great hall at Selucia-Ctesiphon, 275 _footnote_;
extra-dossed arches, Roman and mediæval, 282-3;
pointed arches, early Egyptian, 155-6;
Babylonian, 275 _footnote_;
early European, 86-93;
semicircular arches, Babylonian, 275 _footnote_;
in Asia Minor, 160;
in Acarnania, 160;
among the Etruscans, 160;
in Ancient Rome, 161-4;
transverse arches cut through the piers of bridges, 213, 214, 270.

ARCHITECTS, great need of their influence in to-day’s
bridge-building, 357;
and also in the work of British highway boards, 43.

ARCHITECTURE, ARABIAN, see “Arabian Arches.”

ARCHITECTURE OF BIRDS, 112;
the use of mud in the building of walls probably copied from birds,
111.

ARCHITECTURE, GREEK, 152, 157-9; lovers of Greek architecture are
overapt to undervalue the Roman genius, 167-8.

ARCHITECTURE, ROMAN, see Chapter III.

ARCHSTONES, or voussoirs, they form the compressed arc of materials
called the ring; in some bridges they are laid in two or three
sets, forming either a double or a triple ring, 305 _footnote_.
The earliest archstones were arranged in horizontal courses, 6;
as in the temple of Rameses II at Abydos, 155;
in the Porta dell’ Arco at Arpino, 156-7;
and the Lion Gate at Mycenae; but at Gizeh, in the great pyramid of
Menkaura, there is a variation from this horizontal method, 156;
Some Chinese bridges have arches built without keystones, 313-14;
the rings being constructed with a few segmental stones from five
to ten feet long, 314;
The Romans extradosed their archstones, as in their bridge at
Narni, 24;
and this excellent practice was followed often in the Middle Ages,
282-3;
The Romans, again, more often than not, bedded their archstones
dry, without mortar or cement, as in most of the arches in the
Pont du Gard, 175 _footnote_;
but feebler masons have failed to copy with success this Roman
method, notably in the restoration of the vast Roman aqueduct
at Segóvia, 184;
and recently Spanish workmen, after rebuilding an arch of the
Puente Trajan at Alcántara, pointed the joints of the whole
bridge in order to bring the masterpiece into keeping with
their own weakness, 186-7. In a few English bridges the
archstones are moulded like church windows and doorways;
examples, Crowland, 304-5;
and the Abbot’s Bridge at Bury St. Edmunds, 305 _footnote_.

ARDASHIR, of Persian history, 202.

ARDÈCHE, in France, the Pont d’Arc at, a natural arched bridge, 6, 89.

ARGUMENTS, concerning the origin of Dartmoor Clapper Bridges, 100-5;
concerning the introduction of pointed arches into French bridges,
84-93;
concerning the introduction of ribbed arches into English bridges,
93-100;
to excuse the evolution from military bridges into defenceless
bridges, 334;
to prove that every sort of strife is a phase of war, vii, and
section ii, Chapter I, pp. 14-52.

ARMADA PERIOD, THE, Spanish cannon belonging to it used in the
Peninsular War, 334.

ARPINO, in Campania, its Porta dell’ Arco, an ancient gate with a
pointed arch belonging to the so-called Cyclopean style, 156-7.

ARQUEBUSE, and the slow development of hand-guns, 333.

ART CRITICISM, ENGLISH, its defects, 168.

ARTIFICIAL LIGHT AND HEAT, the first missionaries, 58.

ARTISTS, we need their help in bridge-building, 357-8.

ASCOLI-PICENO, and her bridges, 200, 201.

ASHFORD BRIDGE, Derbyshire, the stump of its mediæval cross destroyed
by parapet repairs, 230.

ASIA MINOR, early semicircular arches have been discovered there,
160.

ASKEATON BRIDGE, its military character illustrated in the “Pacata
Hibernia,” 260.

ATREUS, THE TREASURY OF, at Mycenae, its domed and circular chamber,
158-9.

AUGUSTUS, BRIDGE OF, at Rimini, 82, 199, 220.

AUGUSTUS CÆSAR, the bridge at Narni belongs to his time, 23.

AUHSIEN, in Western China, an iron swing bridge is found there, 345-6.

AURELIUS, PONS, another name for the Janiculine bridge in ancient
Rome, 197.

AVIATION, see “Airships” and “Aeroplanes.”

AVIGNON, her famous bridge built by St. Bénézet. See “Bénézet.”

BABYLON, some of her ancient bridges, 127;
the great bridge built by Semiramis, 273-4;
Babylonian arches, semicircular, pointed, and even elliptical, 275
_footnote_.

BABYLONIAN BRIDGES AND ARCHES, 127, 273-4, 275.

BAD DECORATION IN BRIDGES, 320-8;
M. De Dartein, his books and views, 319-20;
see also under “Engineers, Modern.”

BAKEWELL BRIDGE, its ribbed arches, 94.

BÂLE, the old bridge at, over the Rhine, 306-7.

BALLAD OF ABINGDON BRIDGE, its value to pontists, 208, 251-2.

BANBERY, a superintendent of the workmen when Abingdon Bridge was
built by charity, 252.

BAMBOO BRIDGES in Western China, 348;
and in Sumatra, 291.

BAMBOO ROPE, how it has long been made in China, 348 _footnote_.

BAND-I-MIZAN, THE, a famous Dike at Shushter in Persia, 202, 204.

BANDITS, in mediæval England, 207, 208.

BARACCONI, quoting from Sextus Pompeius Festus, proves that in very
early times human victims were thrown into the Tiber, 64.

BARAMULA, in Kashmír, its fine bridge with criss-cross piers, 73.

BARBER, GEOFFREY, contributed a thousand marks to the building of
Abingdon Bridge, 252.

BARDEN BRIDGE, in Wharfedale, its angular pier-shelters for
foot-passengers, 258 _footnote_.

BARING-GOULD, S., on the Devil’s Bridge, twelve miles from
Aberystwyth, 66-9;
on sacrifices anciently offered to the Spirits of Evil, 68;
on Dartmoor bridges, 103;
mentions some of the arched entrances to caves on the coast of
Pembroke, 150 _footnote_.

BARKING, ABBESS OF, the trustee of Queen Mathilda’s endowment of Old
Bow Bridge, twelfth century, 98.

BARNARD CASTLE BRIDGE, a chapel used to grace it, 231;
see also the colour plate facing page 232.

BARONS, LAWLESS, in Mediæval England, 207 _footnote_.

BARROW, English traveller in China, his remarks on some Chinese
arches, 313-14;
and on the bridges of Hang-Cheu, 365-6.

BARROWS, LONG, Prehistoric, 139.

BARRY, E. M., R.A., protested energetically against the bad taste
shown by modern engineers in bridge-building, 77-8.

BARTHELASSE ISLAND, and the Bridge of Avignon, 237.

BARTOLOMMEO, PONTE S., another name for the Pons Cestius, according
to Palladio, 196.

BASLOW BRIDGE, its ribbed arches, 93;
and its shelter-places for passengers, 258 _footnote_.

BATH, William Pulteney’s Bridge at, 221.

BATTLE BRIDGES, see “War-Bridges.”

BATTLE, LAW OF, vii, 4;
its relation to roads and bridges, see sections i and ii of