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French

The barrel vault of the Roman style (Roman/Greek) is very heavy and requires very thick walls, reinforced significant buttresses, because the weight of the stones of the vault, presses this one downwards by gravity and so lengthens its arc so that the walls are pushed outside at the top (see the dotted lines which simulate displacement); only the weight of the walls and the buttresses makes it possible to oppose  these forces ; openings are thus very few and small bus one should not introduce any brittleness (the port-holes of planes are small and round not to weaken the structure); height and width are limited.

PICTURE, French translation ; arc rond: barrel vault - murs épais : thick walls - poussée : push - poids : weight - contreforts : buttresses

 

 Gothic architecture brings the broken arc  (pointed at the top and not round); leaning on groups of pillars (4, 6 ..), these arcs are connected at their top on a stone known as keystone. they form an intersecting rib. This basic module is repeated then throughout the nave; gothic also creates the flying buttress, which takes support themself on a strong pillar, known as abutment, whose is toped by an arrow or turret (pinnacle) wich weighs down  (and not for the aesthetic, although they are worked).

It's a very complex architecture in the connection of the forms, very daring, inventive and contemporary, comparable with our modern constructions if both steel and tconcrete had been known. Because a Gothic cathedral is a skeleton formed with lots of pillars supporting a great deal of stone arcs (ogives crossings), the whole being reinforced by external jambs (flying buttresses) which will stand the forces pushing  towards outside, these forces coming from  the stone arcs of the top between which the stones of the ceiling will be posed. It is necessary to adding a whole reinforcement of staples and plugs between the arcs (in particular for the rosettes), and also heavy iron belts of Tolede which connect the pillars between them (Reims, Amiens and all the large ones); run lead ensures the cohesion between  iron and stone. The remainder would be only filling if the walls also did not have a blocking effect, without omitting the wings of the transept (cross shaped), nor the frontage, which also brought rigidity.

 Arches of the Gothic envolve reducing the weight of the stones of the vault, increasing both the width and height, the whole finally leading to large openings in thinned walls. But the efforts remain the same as the Roman vaults (drawing of left) and pillars and walls are pushed towards outside for the same reasons. At the beginning, before the invention of the external bracket, heavy galleries were built inside to pull in to some extent both pillars and walls. External buttresses supplement the action of this device (left part of the drawing below).

After the invention of the flying buttresses, one removes the galleries.

PICTURE, translation French/ English ; ici, 4 piliers portent 4 arcs brisés : here, 4 pillars bear/hold 4 broken arcs - pierre clef de voûte : keystone - arc-boutant : flying buttress - pilier contrefort "dit de culée" : abutment - croisée d'ogive : intersecting ribs.

In spite of the lightening of both walls and vault of the ceiling (*), forces exerted by the vault are such that pillars and walls lean outside at the top to some extend   making a kind of small visible swelling at the top if one can find a vertical reference mark in the vicinity, like the pipes of orgues for example, or the wire of a gloss. Fortunately, the skeleton of such a building has an astonishing elasticity (relative of course, for a few centimetres).

(*) it is obviously quite relative because they are great quantities of stones which still weigh very heavy; it is known that the only keystone weighs from 400 to 600 kilos !


The archbishop is the work Master and chooses the Builder. In order to assemble the vaults, one build huged forms of wood reaching the top and one poses the stones onto; the wood is then removed and that holds itself. Lastly, not always. At the end of the XIII th century, the forests had suffered from these enormous taking away for of structural timber.

Originally, there were neither chairs nor benches in the cathedrals which were free open places, where people came to chatter, often in gallant company, or to deal some businesses, to rest (travelers, peasants.. coming from the countryside picnicked in there and cathedrals were also the town hall.

Cathedrals were painted colors sharp, inside like outside.

The end of the cathedrals coincides, in France but not in England or Germany, with the beginning of the hundred year old war (French against English); after the fortified castles, came castles and palates. The cathedrals were forgotten and considered as a bit outdated and monstrous ; they were given the  name of Gothic, from the Goth, barbarian (ostrogoths, barbarians from east, Visigoths from west). Note; Barbar means "stranger" nothing more.


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