Constructing the Nave

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.

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.

The Work Process

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.

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.”

Engineering News Record, 1926

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• Indiana Limestone Company
• New York Public Library, Digital Collections
• Engineering News Record, Vol. 97, No. 13, September, 28, 1926
• The Cathedral of St. John the Divine, Its Progress Pictured, January 1928, Avery Architectural and Fine Arts Library