As. we close out year three of the Divine Stone Project, we thank all of our readers, supporters and contributors. This year we posted 21 stories, the total for the project is now 90 small dives into the amazing story of the stonework at the Cathedral of St. John the Divine. The archives contain all of these. The stories roll on and we’ll keep them coming.
Looking Back.
With sadness, we celebrated the life of Jose Tapia whose spirit is imprinted on the the Southwest Tower. Robert F. Rodriguez authored a 40th anniversary post along with photos and videos on the dedication ceremony for the tower. Additionally, he produced a unique video interview with Philippe Petit about his memories of that day. Wayne Kempton, Archivist, and Tom Fedorek, Senior Guide continue to bless us with supportive information and insights.
Mark and I presented the stone work history of the Cathedral at the 18th annual Stonework Symposium in October of 2022. This event was sponsored by The Stone Foundation. Additionally, Mark Saxe acquired access to John Barton’s slide image library from his time at the Cathedral. John was the Architect-in-Residence during the Dean Morton era. Stephen Boyle reached back and provided descriptions and methods of setting the stone on the Tower.
Looking Forward
We are rounding the corner on the construction of the majestic Nave which will end with a focus on the West Front. There was some carving activity on the West Front in the 1960’s and we will cover that and some special contributions by Canon West. Shortly, we will be back to the Dean Morton era and more stories about the cutters, carvers and setters of that period.
We always welcome comments, suggestions, guest authors and storytellers. Please help keep the stories roll on.
Scientific American, J. Bernard Walker, November 1927
That is the premise of this article in Scientific American from 1927. The Thirteenth Century French style nave is marked by great simplicity and dignity. It has the fundamental characteristics of the cathedrals of Notre Dame, Chartres, Ameins and Rheims. Among these, the interior of St. John’s nave is unmatched for sheer majesty. A review of the building methodology of the nave goes a long way to answer the question. Will it last 5,000 years?
Both the exterior granite and the interior limestone in themselves will last that long. So, what other factors can determine how long that building will last? The author, an engineer, suggests three: design, poor ancillary materials and workmanship. He suggests that St. John’s greatly surpasses, in its structural strength and workmanship, the cathedrals of the Middle Ages.
The Design Compromised by Material Availability
The drawing above compares a pier in Gloucester Cathedral (1100 A.D.) and one of the intermediate piers of St. John’s. The builders of the Twelfth Century Norman Church, and all the later medieval churches, could not afford to construct their piers of cut stone throughout. They built an exterior shell of fine squared stone, from six to twelve inches thick. They then filled the center with a core of rubble set in lime mortar.
When the load of the upper walls came upon such piers, the rubble core settled more readily than the carefully jointed ashlar casing. With the passage of centuries, the mortar frequently disintegrated and the center rubble core lost its bearing quality. The whole load rested on the thin outer shell, which would bend or bulge, flakes of stone splitting off, and the work threatening an early fall.
The more slender intermediate piers of St. John’s have amazingly slender proportions, a diameter of 5 feet to a length of 98 feet. To guard against any buckling under the load they carry, each course became a single granite block. These blocks weigh up to 4 tons each, set with thin cement mortar joints.
Medieval Churches Limited to Small Stone
In those early days, money was scarce and the world had lost many of the secrets of construction, notably that of the making of the cement. This was the ingredient that made for the lasting work of the Romans. It was an age of small stone and mortar construction. Lack of suitable tools and appliances at the quarries, poor roads and inadequate means of transportation had an impact. This and the lack of capital drove the early builders to the use of small size building stone. In binding this material together, they were restricted to the use of lime mortar. Some of this was good, but much of it, as many a catastrophe proved, of wretched quality.
The Main Piers
The main piers measure 11 feet by 16 feet, 3 inches. They consist of a heavy outer casing of multiple ton Indiana limestone with an inner core of massive squared granite blocks. Each granite block weighs between 5.5 and 7 tons.
Towers Collapse and Piers Buckle in Medieval Cathedrals
In both English and French cathedrals built in the Middle Ages there have been many building problems. Chichester, Ely, Wells, Salisbury and Beauvais have experienced these problems as well as tower collapses, failures and the need for heroic measures to shore up the building. The settlement of the masonry under the thrust and counter thrust of vault and flying buttresses have caused much of this.
Stone vaulting for the nave at St. John the Divine. Keystones weigh up to 5 tons
St. John’s has been designed and built with a careful avoidance of the pitfalls which so often brought disaster to certain medieval churches. The load upon every pier, the thrust against every buttress, has been calculated with close exactness. The crushing strength and the safe limit of loading of each kind of stone are known.
This cross-section illustrates the strength and mass of the abutments. The thrust of the nave vault, great though it may be, will never push these huge masses of out of plumb. They may well be in place for 5,000 years.
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Building for the Ages, J. Bernard Walker, Scientific American, November 1927
All images and drawing are from the above article as is the 5,000 Years question.
Foundations, Basement and Floor of the Nave, approximately 1918
The Cornerstone of the Nave was dedicated by Bishop Manning on November 9, 1925
Jacob & Youngs, contractors for the Nave, had three construction issues to resolve for constructing the Nave. One, to reduce to a minimum the fire hazard of scaffolding; two, the centering of 250 ton stone arches that would crown 120 feet above the floor; and three, a design for the centering system that could adapt itself progressively to an increasing height up to 100 feet, all the while supporting scaffolding and erection derricks. The contractor selected a steel structure to deliver the 90,000 stones.
August, 1925
They erected eight steel towers (4 pairs) to varying heights as needed. These towers would support hoisting rigs, scaffolding and centers. The towers could provide material to the two lines of piers on each side of the Nave, the outside walls, the buttresses and the arch vaulting of the ceiling.
Various passageways and runways honeycomb the steel structure. These are to facilitate transporting material. Six twenty-ton derricks top off the steel towers to move the heaviest material. The derricks have 70 foot booms. The derricks are operated by direct current electric hoists of 50 and 75 horsepower.
Material yards on each side of the building were convenient to the large derricks on the towers. Small hand derricks on the ground move the stones around the yard. A foreman in each yard is responsible for sending up the proper pieces when needed. The limestone arrives carefully wrapped in burlap. Since most of the pieces are small, a number of the them were hoisted on a skip. On the other hand, the large pieces of granite and limestone are hoisted one at a time and deposited in place by the large derricks. Some of the pieces of granite weigh 12 tons. Small hand derricks can place the limestone and smaller granite .
In addition to the two material yards, a shop is maintained on the job where the finishing touches are put upon the carved stone. The cement mortar is mixed by hand in the crypt below the floor. It is placed in wheelbarrows and carried up to the working platform by an elevator operated by a 35-hp. electric hoist.
Image – Indiana Limestone Company
The ordinary masonry gang consists of a stone setter who is gang boss, fitter, and two derrick men. One of the derrick men assist the fitter and the other operates the bell signal rope to the hoist house on the nave floor. The hoist engineer completes the gang personnel. The gang varies slightly where hand hoists are used exclusively. These gangs are distributed one on each pier and at intervals along the walls. The total labor force numbers 175 to 200 men. David Bell is the superintendent in charge.
Constructing the Nave, Opinion from 1926 – Engineering News Record
“Structurally the Cathedral is medieval. It is true masonry, not concrete and tile and steel. Arch and wall, buttress and pillar are cut and carved stone. In its construction there are some modern touches. Where in old cathedrals the stone was shaped by the mallet and chisel, it is now made ready largely by the stone dressing machine and the pneumatic tool. The former mazes of timber staging and centers are replaced by a comparatively simple supporting structure and working platform of steelwork. The electric elevator and derrick now do the work of hand winches and many human carriers.
Today the old methods would have put the cost beyond count. Even by the measure of modern methods and machines, here was a difficult construction task. There are repeated circumstances, as may be observed on the cathedral work, in laying fine architectural stone masonry where old ways and tools cannot be bettered. No power hoist can surpass the hand winch in convenience and precision in lining in, for example, the stones in the clustered columnar piers. But without modern methods the practicability of such a structure would be doubtful. Out of them come speed and safety and a limited need of workmen. Out of this gain came economy and the possibility of reproducing a medieval type structure at present day prices and wages.”
