Choir crypt and basement walls, 1675

WRE/2/1

7 drawings

{\rtf1\ansi\ansicpg1252\deff0\deflang2057{\fonttbl{\f0\fswiss\fprq2\fcharset0 Microsoft Sans Serif;}{\f1\fswiss\fprq2\fcharset0 System;}} {\colortbl ;\red0\green0\blue128;} \viewkind4\uc1\pard\cf1\f0\fs20 These seven drawings are preparatory for two main phases of construction in the eastern arm and crossing that were begun, or contracted to be begun, between June and August 1675.\par \par On 18 June masons Thomas Strong and Joshua Marshall signed contracts to build the the crypt of the eastern arm (or choir) and east side of the crossing from foundation level to the tops of the imposts (or capitals) of the piers which carry the brick vaults of the crypt. The tops of the imposts are level with the ground externally, and construction up to this level comprised the first main phase of work in 1675.\par \par On 17 and 20 August Strong and Marshall contracted to build the masonry of the external basement walls from external ground level to the top of the plinth of the basement. The top of the external basement is level with the church floor internally. By late September construction had risen to the imposts of the crypt (Wren Society 16, pp.7-10, 208-12). Work on the basement walls began in March or April 1676. These walls are level with the brick vaulting of the crypt. Bricklayer Thomas Warren contracted to build these vaults in June that year (Wren Society 16, p.14; and 13, p.79).\par \par The earliest known design for the crypt is a quarter-plan with two sections, WRE/2/1/1. Wren had revised this scheme before the contracts of 18 June 1675, for in the fabric the impost of the pier is lower than shown in this drawing (about 11 ft 6 inches above the original floor level, instead of 12 ft in this drawing). Consequently, the profiles of the vaults as built are steeper than in this drawing. Lowering the piers allowed Wren to heighten the vaults by about 6 inches, while maintaining an overall height of 20 ft 6 inches from the floor of the crypt to the church floor. A drawing by Edward Woodroofe, WRE/2/1/2, shows the section of the aisle vault with a steeper profile than in WRE/2/1/1. A height of 9 ft 2 inches is indicated from the top of the impost to the church floor. Woodroofe marked the same dimension on a drawing for the vaulting in an aisle recess of the crypt, WRE/2/1/3 (developed from a preliminary study in another hand, WRE/2/1/4). \par \par The contracts for the basement walls in August 1675 describe 'Six Courses of Plinth & Rustick Ashler with the Coines and Windows & rustic Arches expressed in the Designe...'. The \lquote designe\rquote in question was a plan, section and elevation drawn by Woodroofe (WRE/2/1/5). Two drawings for the basement of the bastions relate very closely to this one (WRE/2/1/6 and 7). All three drawings show the basement at its built height of 9 ft, instead of the 9 ft 2 inches marked on the vaulting studies. This small difference indicates that the vaulting studies, WRE/2/1/2-4, belong to an earlier phase in the design of the crypt. Confirmation is found in two early sectional drawings for the south-east corner bastion which show the vault and external basement together, the latter not as built, and 9 ft 2 inches high (see WRE/2/2/3 and 4). \par \par After visiting Wren on 5 June 1675, Robert Hooke wrote in his diary that the Surveyor was \lquote making up my principle about arches and altered his module [design or model] by it\rquote . This comment may be a record of a change in the profiles of the vaults of the crypt, illustrated in WRE/2/1/2, for Hooke\rquote s \lquote principle\rquote was that of the catenary-shaped \lquote hanging chain\rquote , whose profile, when inverted, offered an optimum shape for an arch in compression (Higgott 2009, p.164).\par \par Once the height from ground level to the church floor had been fixed at 9 ft, further changes were made to the profiles of the vaults before they were begun in June 1676. A long section through the east end of the choir at crypt and church-floor levels appears to illustrate this phase (see WRE/2/3/6).\cf0\b\f1\par }

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