ARCHITECTURE. 
126 
elation, they employed mortar of a peculiar quality, made 
tip of roach-lime'and fharp gravel; and with this they 
began to lay the firll courfe, ramming in large flat ftones 
upon it to about a foot thick. On this firll courfe they 
laid a plentiful coat of dry lime and gravel of the fame 
quality, on which they again laid Hones, and then pro¬ 
ceeded to lay mortar as at firll, and continued to do fo al¬ 
ternately till they came to a perfect level with the piles. 
Fattened down to. the end of thefe piles were laid,three 
beams, firetching' the whole length of the pier from fier- 
ling to fterling, the intervals of which being filled up 
with mafonry. On this platform, which w'as four feet lix 
inches under low-water mark, they began to lay the firll 
courfe of Hones for the pier, cramped together, and jointed 
with terrace-mortar as ufual, and went forward till they 
came to a level with the water at ebb-tide. 
About the year 1765, the foundation of a Hone bridge 
acrofs the river Tees, near Stockton, was laid by Mr.-Shout. 
The workmen began with firll making very flrong coffers 
of.folid fir-timber about ten feet fquare, which they piled, 
jointed, and fecured, one upon another, till they had gained 
a fufficient height to exclude the water at its highelt tide. 
The joints of thefe timbers they caulked in the lame man¬ 
ner as (hips are; and, launching them without any bottoms, 
they fixed them down to their refpedlive Hations in the 
river. On the outfide and infide they drove a number of 
piles, which they boarded and rammed with clay, to pre¬ 
vent the water from oozing in at the bottom of the coffers. 
This indeed was their greatefi difficulty, for, owing to 
quickfands and other loofe flrata through which the water 
iprang in, the labour of digging to the proper kind of 
foundation was immenfe. The chain-pumps played incef- 
fantly, and by a refolute perfeverance, the work, which 
at fome periods feemed to bid defiance to human indufiry 
and Ikill, was at length brought above low-water mark. 
The bridge is neat and plain, and continues to the prefent 
time a proof of the folidity of its foundation. 
With refpedl to wooden bridges, there are various me¬ 
thods of confirudting them, fo as to anfvver valuable pur- 
pofes, and even to laH a confiderable time. The inven¬ 
tion of wooden bridges was certainly prior to thofe eredled 
of Hone ; two or three different kinds are deferibed by Pal¬ 
ladio, after the manner of the ancients. Some of thefe 
are one continued frame of wood contpofed of a number 
of parts, and connected together by lap-joints and iron- 
bolts extending quite acrofs the river, without any piles to 
iupport them; depending entirely on the truffed parapets, 
and on the manner of fixing thefe frames on the Hone hut¬ 
ments. The principal and moH effential points of wooden- 
bridge building are two ; firfl, to feafon and prepare the 
wood fo as to make it hilling; and lecondly, to lay a proper 
and durable pavement on the top. 
In feafoning the wood for this purpofe, the following 
particulars fliould be attended to : the Hidden decay of fir 
timber generally is owing to the fappy nature of its exte¬ 
rior furface, which is by no means capable of being reme¬ 
died by any immediate application of paint previous to its 
being feafoned : on the contrary, it has been proved, that 
fuch an application is actually injurious, lince it hinders 
the free admillion of air and heat, which would have the 
property of extracting that fappy quality which fo much 
contributes to decay and rottennefs. In confequence of 
this praClice, the lap firikes inwardly and makes its way 
to the heart of the wood, the fubfiance of which is pre- 
fently contaminated and defiroyed. As a means of pre¬ 
venting this evil, fome burn and fcorch the timber over a 
flaming fire, turning it about till every fide acquires a fort 
of crufiy furface ; and, in doing this, it neceffarily follows 
that the external moiflure is dillipated. After this procefs, 
a mixture of pitch and tar, fprinkled with fand and pow¬ 
dered fiielis, may be advantageoully applied to the parts 
under water. Thole more in fight, after being well fcorch- 
ed, and while the w'ood is hot, fhould be rubbed over with 
’infeed oil mixed with a little tar. This will Hrike deeply 
into the grain of the wood, and will foon harden fo as to 
receive as many coats of paint as may appear neceffary. I* 
has been found that fir-timber thus prepared is nearly equal 
to oak for durability. 
Among the Romans, the repairing and building of 
bridges were committed to the priefis, thence named pon- 
tifices ; next to the cenfors, or curators of the roads; but 
at lall the emperors took the care of the bridges into their 
own hands. Thus, the Pons Janiculenfis was built of mar¬ 
ble by Antoninus Pius; the Pons Cellius was reHored by 
Gordian ; and Arian built a new one which was called af¬ 
ter his own name. In the middle age, bridge-building 
was counted among the acts of religion ; and, toward the 
end of the twelfth century, St. Benezet founded a regu¬ 
lar order of hofpitallers, under the name of pontifices, or 
bridge-builders, whofe office was to allifi travellers, by 
making bridges, fettling ferries, and receiving Hrangers in¬ 
to holpitals, or houfes, built on the banks of rivers. We 
read of an hofpital of this kind at Avignon, where the 
hofpitallers relided under the direction of their firll fupe- 
rior St. Benezet: and the Jefuit Raynaldus has a treatife 
on St. John the bridge-builder. 
Among the bridges of antiquity, that built by Trajan 
over the Danube, it is allowed, is the moH magnificent. 
It was demolilhed by his next fucceffor Adrian, and the 
ruins are Hill to be feen in the middle of the Danube, near 
the city Warhel in Hungary. It had twenty piers, of 
Iqnare Hone, each of which was 150 feet high above the 
foundation, (ixty feet in breadth, 170 feet difiant from one 
another, which is the fpan or width of the arches; fo 
that the whole length of the bridge was more than 1530 
yards, or one mile nearly. 
In France, the Pont de Garde is a very bold flruClure; 
the piers being only thirteen feet thick, yet ferving to fup- 
port an immenfe weight of a triplicate arcade, and joining 
two mountains. It conlills of three bridges one over the 
other; the uppermofl of which is an aqueduCl. The 
bridge of Avignon, which was finiffied in the year 1188, 
confifis of eighteen arches, and meafures 1340 paces, or 
about 1000 yards in length. 
The famous bridge at Venice, called the Rialto, pafles 
for a mafler-piece of art, confifling of only one very flat 
and bold arch, near 100 feet fpan, and only twenty-three 
feet high above the water: it was built in 1591. Poulet 
alfo mentions a bridge of a fingle arch, in the city of Mun- 
fter in Bothnia, much bolder than that of the Rialto at 
Venice. Yet thefe are nothing tea bridge in China, built 
from one mountain to another, conlifling only of a fingle 
arch, 400 cubits long and 500 cubits high, whence it is 
called the flying-bridge. Kircher alfo fpeaks of a bridge 
in the fame country 360 perches long without any arch, 
but fupported by 300 pillars. 
There are many bridges of confiderable note in our own 
country. The triangular bridge at Crowland in Lincoln- 
fhire, it is faid, is the molt ancient Gothic HriuSture re¬ 
maining entire in the kingdom ; and was erected about the 
year 860. London-bridge is on the old Gothic firufhire, 
with twenty fmall locks or arches, each of them only 
twenty feet wide ; but there are now only eighteen open, 
two having lately been thrown into one in the centre, and 
another next one fide is concealed or covered up. It is 
900 feet long, fixty high, and 74 wide ; the piers are from 
twenty-five to thirty-four feet broad, with flerlings pro¬ 
jecting at the ends; fo that the greatefi water-way, whea 
the tide is above the flerlings, was 450 feet, fcarcely half 
the breadth of the river; and, below the Iterlings, the 
water-way was reduced to 194 feet, before the late open¬ 
ing of the centre. London-bridge was firfi built with tim¬ 
ber between the years 993 and 1016; and it was repaired, 
or rather new built, with timber, 1163. The Hone bridge 
was begun in 1176, and finilhed 1209. It is probable there 
were no houfes on this bridge for upwards of 200 years; 
lince we read of a tilt and tournament held on it in 1393. 
Houfes it ieems were erected on it afterwards; but, being 
found of great inconvenience and nuifance, they were re- 
jllQVed in 1758, and the avenues to it enlarged, and the 
whole 
