A study drawing for construction, attributable to Edward Strong, but with some penciled additions probably in Wren's hand. Implied scale, 4 ft to 1 inch.
The drawing shows, in laid-out elevation, the arch and flanking columns of the central bay of the upper apse. The apse-elevation is presented with a profile of the wall and column on the left, and another of the internal attic at centre-left, although not as built, not at the correct level. The drawing can be assigned with some confidence to Edward Strong from the handwriting in the inscription: '30 foot to ye centre of ye Circle'. This compares closely with the hand in several signed notes by Strong in the St Paul's Cathedral Acquittance books, especially in the z-shaped form of the secretary lower-case 'r'.
When Thomas Strong died in 1681, Edward took over his older brother's areas of construction, including the east end of the choir. In May 1686 scaffolding was erected 'on the outside of the east end for the Masons to set the Plinth' (Wren Society 14 p.6). The drawing is datable shortly before the start of work at this level. The plinth course in the drawing is exactly as built, with tiny projections in the courses marked in inches against the left-hand profile. Above this level, the channeled stone courses conform to the fabric. The internal attic, at centre-left, lacks a dentil course in the upper cornice, and panel mouldings on the dado. it, too, was begun in may 1686. Presumably for convenience, this feature is placed about 1 ft higher than it should be in relation to the external order. The profile of the internal cornice below the attic has been summarily sketched at less than its actual height and depth. Details of the architrave and keystone of the central arch have been tried out in pen and pencil. Stone courses for the columns have been added in pencil, although fewer than built.