The great eastern stone arch looms above Morningside Heights at the close of the nineteenth century. It was the signature image of the cathedral construction in those days and the culmination of years of excavation and foundation building. The keystone was only half an inch out of position laterally and 3/4 of an inch vertically when the arch completed. Before any of that began however, it is important to understand the significance of the Romanesque arch in the design by Heins and La Farge.
In their design, the number one key feature was a large crossing. The crossing is the intersection of the transepts and the nave. They explain the aim of this crossing plan as follows: “so that the greatest possible number” of people “may be properly so placed as to see and hear.” To accomplish this, four rounded or Romanesque arches create a 96 foot square at the crossing. The typical Gothic crossing using pointed arches is about 47 feet.
Support for the Lantern
Additionally, the design called for a massive 16-sided lantern/tower above the crossing, supported by the four Romanesque arches. The place of hearing was also to be the greatest source of light in the cathedral.
The ground floor plan shows four very large square piers standing at the corners of the crossing. Next to each of these and set at right angles with them, are two smaller piers – eight in all. Between the larger piers spring the four great arches which bound the crossing and carry the central tower. From the outer piers spring buttress arches meeting the great arches at about their point of springing. Both piers and arches are of the most solid granite blocks because of the enormous weight they have to bear. The load upon the base of each of the four corner piers, according to the architect, will be about 35 million pounds.
Architect Grant LaFarge had the following to say regarding the recent use of concrete and steel construction. “As to structure, this quality can be insured only by the use of imperishable materials in visibly massive construction. Any device as the modern steel frame, commercial and of unknown duration, is instantly to be dismissed; so, too the indiscriminate use of the hasty and half understood concrete, treacherous, but dear to the engineer. A building of masonry, with true vaulting, is the only possible thing.” Stone on stone construction was the order of the day.
“A building of masonry, with true vaulting, is the only thing.”
– C. Grant La Farge
Excavation, Foundations, and Piers
The soil and rock lacked stability after the siting and the laying of the cornerstone in 1892. They built St. Luke’s Hospital across the street on bedrock at grade. At the Cathedral, excavation had to go as deep as 72 feet in places, through all rock of poor quality to underlying solid strata no less than 20 feet in thickness.
Once the excavation was down to bedrock, dewatering took place and the workers laid footings of Portland cement. The massive granite blocks for the foundation of the eastern stone arch began to move in. Then the piers began to rise, 38 square feet at the base.
The Eastern Stone Arch and Buttresses
The springing line at each of the great arches will be 16 feet above the top of the 79 foot pier and its span will be 114 feet from tip to tip of the voussoirs. The clear span is 96 feet. The voussoirs are granite and cut to template. The rise was 55 feet. They weighed between 3 and 6 tons each and laid in mortar of Portland cement.
Arch construction depends essentially on the wedge. These wedge shaped blocks are called voussoirs. Each voussoir must be precisely cut so that it presses firmly against the surface of neighboring blocks and conducts loads uniformly. The central voussoir is called the keystone. The point from which the arch rises from its vertical supports is known as the spring, or springing line.
After the deaths of Bishop Potter (1908) and the architect George Heins (1907), the trustees did not renew the contract for architect La Farge (1911). The work on the transepts was not completed nor the great lantern/tower. The Crossing, Choir, Chancel and Apsidal Chapels were complete. The Crypt hosted services. The selection of a new architect was in the works. The love affair with the unique mix of Byzantine, Romanesque and Gothic greatly diminished. The crossing would remain the dimmest place in the cathedral.
- Scribners Magazine, V. 41, 1907
- The Churchman, May 30, 1891, Competitive Design, Heins and La Farge
- Scientific American, Building Edition, October 1900
- Columbia University Library
- New York Public Library