Life in a Medieval City
Page 12
Cathedral of St.-Pierre, Troyes. Begun in the early thirteenth century, its construction, like that of most cathedrals, was interrupted for long periods by lack of funds, and was not finally completed until the sixteenth century. (Touring-Club de France)
The names of builders are well known to prospective employers. William of Sens was hired in 1174 to rebuild Canterbury Cathedral on the strength of his reputation as the builder of the Cathedral of Sens. Builders are well paid, with a liberal daily stipend supplemented by a clothing allowance, a food allowance, fodder for their horses, a fur-trimmed robe, and often special privileges, such as freedom from taxes for life. Typically rising from the ranks of the masons, they are remarkably versatile. Not only do they habitually combine the functions of engineer and architect, but some are adept sculptors and painters, or even poets. They are expert at every kind of construction—castles, walls, bridges, secular buildings. One architect, John of Gloucester, not only supervised the works at Westminster Abbey, but undertook at Westminster Palace to repair a chimney and a conduit supplying water to the king’s lavatory, and to build a drain to carry off refuse of the kitchen to the Thames, “which conduit the king ordered to be made on account of the stink of the dirty water which was carried through his halls which was wont to affect the health of the people frequenting them.”
The builders’ plans2 are skilfully drafted on parchment, to explain their intentions to bishop and chapter: ground plans for each part of the nave, choir and transepts, sketches of portals with sculpture indicated, scale drawings of bays and ambulatories, variant possibilities for roofing and drainage. Accomplished mathematicians, especially strong in geometry, they determine proportions by supplementing measurements in feet and inches with modules, based on squares, equilateral triangles, and other regular polygons. This knowledge is so esoteric that it remains a professional secret.
The master builder is not only well paid but highly respected, as are the master masons. A preacher cannot restrain his indignation in describing the lordly status of these elite commoners: “In great buildings the master-in-chief orders his men about but rarely or never lends his own hand to the work; and yet he is paid much more than all the others…The master masons, with walking sticks and gloves, say, ‘Cut here,’ and ‘Cut there,’ but they do no work themselves.”
The flying buttress, a key element in the revolutionary Gothic system of construction, drawn by Villard de Honnecourt at Reims Cathedral.
The master builder is the general of a skilled, and consequently expensive, army of workers. Pilgrims and other faithful sometimes contribute voluntary labor, usually in the transport department. Occasionally a long line of penitents hitch themselves to a wagonload of stone, doing the work of oxen. On the whole, oxen do the work better. A more efficacious form of volunteer labor is the peasant with ox and wagon who receives an indulgence from the bishop in return for his help. Even so, moving a large quantity of stone a long distance overland is a serious problem. Troyes imports some of its stone from Tonnerre, only twenty-five miles south, but without a connection by water. The stone quintuples in cost on the journey. Water transport is much cheaper. The marble for the columns of the great abbey church at Cluny was moved ten times as far, down the Durance from the Alps and up the Rhône. When they can, bishops cannibalize pagan monuments, as at Reims, where an early archbishop obtained permission from Louis the Pious to dismantle the Roman ramparts so that he could build the old Romanesque cathedral.
But a convenient quarry is even better than an old Roman wall. Suger’s discovery of the quarry at Pontoise was regarded as miraculous. The bishops of Troyes have a quarry which is worked by masons from the cathedral work gang.
Never do volunteers figure as an important element of the labor force. They cannot dress stone, or set it in courses, or make mortar and tile, or lay lead roofs and gutters, or construct arch ribs, or sculpture stone, or carve wood, or fabricate stained glass, or assemble it into windows. Cathedral labor is necessarily professional.
In the terminology of construction workers of a later day, the masons are “boomers.” They go where the job is, living in barracks in the cathedral yard, collecting their pay, saving it if they are prudent, spending it on drink and girls if they are not. Many own their own valuable tools, which are passed from father to son. Others depend on tools supplied by the employer, who is normally responsible for repair and maintenance. Keeping soft iron points and edges sharp is a problem. Besides picks, hammers, wedges and points, basic to stone dressing, masons need hatchets, trowels, spades, hoes, buckets and sieves for mortar, and lines for laying out walls.
Masons are free men, skilled at their profession, capable of rising in the world. There are several categories with varying wage rates: plasterers and mortarers, stonecutters, master masons, and unskilled laborers. They usually spend their first years in the quarry, learning to cut stone. A mason in the quarry may be paid twenty-four deniers a week plus his meals and lodging, though in winter his wage is automatically cut to match the shorter working day. A summer wage may reach thirty deniers. There is plenty of work for an expert mason; from eight to ten churches a year are going up in France alone.
On a summer day, the workyard before a cathedral hums with activity. Masons are clustered in twos and threes. One man hammers while a comrade holds the point to the stone, cutting a voussoir, one of the wedge-shaped stones that form the ribs of an arch. Most difficult to fashion is the keystone, whose projections must fit into cuts made in the four rib stones that meet it, to pin the vault securely at the top. Some workers are dressing stone blocks for the exterior masonry. The Master of the Works, or one of his aides, may construct wooden “molds” against which the stone blocks are measured to insure uniformity and accuracy. A master mason marks each finished block with a number, to facilitate assembly of the great jigsaw puzzle. Some men are at work on more delicate pieces, sections of pier capitals or portal frieze borders. Some are busy making mortar with buckets, sieves, hoes, and trowels. They have the valuable assistance of a recent invention—the wheelbarrow. Two blacksmiths are sharpening tools, one turning the grindstone as the other hones the cutting edge of a hatchet. One shed shelters a forge where the iron clamps3 and dowels are wrought. Another is the carpenters’ shack, near which is the pit where the heavy beams for the timbering are sawed by the big two-handed pit saw. The plumbers also have their shed, where they fashion lead fittings for eaves and gutters.
An exceptionally skilled craftsman at work in the yard may be the bell founder, really a brass founder, who makes brass pots, washbasins, and mortars when there are no bells to be cast. He has a large pit dug, and in it he constructs a mold with a clay core which supports a wax model of the bell, in turn encased in a clay “cope.” The mold will be dried by kindling a fire in the brickwork of the core, which will at the same time melt the wax, leaving a space to be filled in with bell metal. This is a mixture of copper and tin. Experience has shown that the best proportion is thirteen parts copper to four of tin; a higher percentage of tin improves the tone of the bell but makes the metal brittle. The bell is “long-waisted”4 (longer in proportion to its diameter than bells in later centuries). It will be rung with a simple lever; later bells will be operated with a half wheel, three-quarter wheel, and finally a complete wheel. The founder casts his bells so that they will have a “virgin ring” and will need no further tuning. Tuning is a laborious and noisy process of chipping around the inside of a bell.
When the metal is poured and the bell mounted, the bishop baptizes it as if it were a child, with salt, water, and holy oil. He prays that when it is sounded faith and charity may abound among men, that all the devices of the devil—hail, lightning, winds—may be rendered vain by its ringing, and all unseasonable weather be softened.
The bell founder signs his work with the mark of a shield with three bells, a pot and a mortar, and sometimes with an inscription such as “Iohannes Sleyt Me Fecit” or “Iohannes De Stafforde Fecit Me in Honore Beate Marie,” or a
bit of bell ringer’s verse: “I to the church the living call, and to the grave do summon all,” or “Sometimes joy and sometimes sorrow, marriage today and death tomorrow.”
Dominating the scene is the great incomplete shell of the cathedral itself. The rising wall is covered with scaffolding fashioned of rough-hewn poles lashed together in trusses, with the diagonals cinched by tourniquets. Inside the walls a giant crane stands on a platform, its long arm reaching over the wall, dangling a line to the ground. When the line is secured around a building stone, word is passed from the ground outside via the men on the scaffold to the crane operator inside. The “engine” is started—a yoke of oxen harnessed to walk in a circle around the crane platform, winding the line on a windlass. The driver commands, the whip snaps, the oxen shove, the windlass turns, the line moves, the block rises, till it reaches the scaffold where the men are waiting. Cries go back and forth over the wall, the “engine” is halted, the men on the scaffold grasp the block, maneuver it in, call for another lift of a foot or so, then for a back-off to lower the stone in place, and amid shouts, commands and perhaps a few curses, the block is securely bedded in the prepared mortar course. Smaller stones are lifted by a lighter windlass, which is turned by a crank—another invention of the Middle Ages.
Most of the masonry work consists of old, long-practiced technique. The Romans maneuvered bigger blocks into position than any that medieval masons tackle. On the Pont du Gard there are stones eleven feet in length. But medieval masons are steadily improving their ability to handle large masses of stone. In the bases of piers, monoliths weighing as much as two tons are sometimes used. The Romans habitually built without mortar, dressing their stones accurately enough so that walls and arches stood simply by their own weight. Some builders are beginning to essay this, but by and large medieval masonry relies on mortar.
Thirteenth-century timbering is also less daring than Roman. The entrance to the choir at present is a veritable maze of heavy crisscrossing timbers supporting the work in progress on the first bay of the choir vault.5 The rough-hewn timbers stand in a network of Xs and Vs, supporting a rude ogival arch of timber on which the stone ribs are laid. The timber arch does not meet the stone accurately at all points, and where it fails to do so, chips or blocks are driven into the interstice.
In the early Middle Ages, the problem of fireproofing a church was reduced to the question of how to support a masonry vault with something less expensive than a thick wall. Roman engineers actually had a solution, the groined vault, contrived by making two of their ordinary semicircular “barrel vaults” intersect. The weight of the resulting structure was distributed to the corners, permitting it to be supported by piers, and so providing architectural advantages. But the groined vault, though used by the Romans in the Baths of Caracalla and by some builders since, presents a difficulty. The variously-shaped stone blocks must be meticulously cut; in other words, they are expensive.
Medieval machinery, sketched by Villard de Honnecourt: top, mechanical saw for splitting beams; upper right, crossbow with sighting device; middle, hoisting machines; lower left, a mechanical eagle.
When medieval engineers found another way to mount a vault on piers they opened the door to Gothic architecture.6 The Romans, acquainted with the pointed arch, found as little use for it as had the Greeks or Persians. It was French engineers of the twelfth century who made the discovery that two pointed arches, intersecting overhead at right angles, created an exceptionally strong stone skeleton, which could rest solidly on four piers. The stones were easy to cut and the spaces between could be filled with no exceptional skill on the part of the mason. And once mounted on its piers, the new vault could be raised to astonishing heights at moderate cost. The higher the vault, the more room for windows, and the better illuminated the church. A problem remained. As the vault rose, the piers required reinforcement to contain the thrust from the ribs, which threatened to topple them outward.
At first this difficulty was met by buttressing, that is, by giving an extra thickness to the exterior wall at the point where the rib connected. But this made it impossible to put side aisles in the church. The spectacular answer to the problem was the flying buttress, a beam of masonry that arched airily over the low roof of the side aisle to meet the point where the rib supporting the main vault connected with the top of the pier.
By 1250 the intricate combination of piers, ribs, and flying buttresses has become an established, functioning system, one which would have opened the eyes of Roman engineers.
Medieval builders have a better theoretical grasp of structural relationships than had their Roman predecessors, who often used unnecessarily heavy underpinnings. But there is still no such thing as theoretical calculation of stress, or even accurate measurement. Gothic churches are full of small errors of alignment, and sometimes a vault crashes. But with or without a grounding in theory, the new technology usually works, and works so well that though originally conceived in a spirit of economy, it has had a history similar to that of many other engineering advances. It has opened such social and aesthetic possibilities that in the end it has raised the cost of church construction. A hundred years ago the nave of one of the first Gothic cathedrals, at Noyon, soared to a height of eighty-five feet. Notre-Dame-de-Paris then rose to a hundred and fifteen feet, Reims to a hundred and twenty-five, Amiens to a hundred and forty, and Beauvais, just started, is aiming at over a hundred and fifty. Spires above the bell towers reach much higher, that of Rouen ultimately holding the championship at four hundred and ninety-five feet, higher than the Great Pyramid.
It is no accident that the development of Gothic architecture coincides with growing affluence. The bishop of Troyes could not have undertaken the new Cathedral of St.-Pierre two hundred years ago, not merely for want of engineering technique but for want of cash.
Money to pay for a cathedral comes from a number of sources. Added to the steadily growing revenues of the chapter and its dependencies are the profits from indulgences, which are the bishop’s monopoly. Many an avaricious baron has made peace with God by a handsome gift to a cathedral building fund. Deathbed bequests7 are an especially fruitful source. The Church has campaigned long and shrewdly in favor of wills. Relics, which are part of the reason for building a cathedral, help raise money long before its completion. They attract pilgrims to the site, and since they are portable, they can be sent on mission to the surrounding countryside. Those of Laon journeyed as far south as Tours and north and west to England, where they visited Canterbury, Winchester, Christchurch, Salisbury, Wilton, Exeter, Bristol, Barnstable, and Taunton, performing miracles all along the way.
Even with all the resources of guilty consciences and psychological cures few cathedrals would be completed without the assistance of an entirely different factor: civic pride. The cathedral belongs to the town as well as to the bishop and is often used for secular purposes, such as town meetings. The burghers can be counted on to give it financial support, not merely through private contributions by the wealthy, but through corporate contributions by the guilds. Proud, devout, and affluent, the guilds compete with each other and with the great lords and prelates in endowing the pictures in glass of Bible stories and lives of the saints which are the chief glory of the cathedral, and which represent no less than half its total cost. For at least one cathedral, Chartres, we have precise figures: of one hundred and two windows, forty-four were donated by princes and other secular lords, sixteen by bishops and other ecclesiastics, and forty-two by the town guilds, who signed their identities with panels representing their crafts.
Windows are not all installed at once. A cathedral’s glass may be incomplete a hundred or two hundred years after the masonry is begun. The installation of a window in the clerestory of the choir is an event. The mosaic of colored glass is passed up from hand to hand and eased onto the projecting dowels of a horizontal iron saddle bar, the ends of which are buried in the masonry. A second narrow bar with openings that match the dowels fits parallel
to the first bar and is fastened to it with pins. Together these bars, and the vertical stanchions, hold the glass in place and brace it against wind pressure.
Glass is not manufactured at the site of the cathedral, nor indeed even inside the city. The glassmakers locate their hut in a nearby forest, which supplies fuel and raw materials. Glassmaking is a very ancient art, and “stained” (colored) glass is at least several centuries old, but not until recently has it been in great demand. The new technology and the new affluence have created this major industry.
The glassmaking process, brought to the West by the Venetians, has changed little through the ages—two parts ash (beechwood for best results) to one part sand in the mixture, a hot fire in a stone furnace, blowing and cutting. Blowing is done with a six-foot-long tube, creating a bubble of glass in the form of a long cylinder closed at one end and nearly closed at the other. The cylinder is cut along its length with a white-hot iron, reheated, and opened along the seam into a sheet. The result is a piece of glass of uneven thickness, full of irregularities—bubbles, waves, lines—not very clear, of a pale greenish color. Medieval glassmakers, like their predecessors, cannot turn out a good transparent, colorless pane. One consequence has been that glass never had much appeal as material for the small windows of the Romanesque buildings.
The vast Gothic window spaces have changed the situation. Imperfections in the glass are unimportant, as coloring becomes not only acceptable but desirable. Colors, apart from the indeterminate green of “natural” glass, have always been readily obtainable by adding something to the basic mixture—cobalt for blue, manganese for purple, copper for red. As the big new church windows came into fashion the glaziers took to cutting up sheets of colored glass and leading bits together to make a design. Almost at once the idea occurred of making the designs not merely geometric but pictorial, and the art of stained glass was born. Art begets artists, and the function of assembling the pieces of glass into pictures that the sun turned into miracles of radiant color devolved on those who were skilled at it.