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image SM (15) volume 74/97

Reference number

SM (15) volume 74/97


Design for the construction of the dome


15 Ground floor plan; section; and rough details of the masonry


bar scale


(Soane) allow for finishing / on the cones about / ½ Inch, Inch / 3, Tieback inch, Q[uer]y one course / of (Cones cancelled) brick under / the last step / except in part / where the stone / step might be / continued thro', No 6 equal part, 1, 2, 3, 4, 5, 6 In / 3, one / piece of / stone, lettered A to G, Make B C / equal / to / C D / Make E F equal to F G, plan labelled: A, Stone, Chain bar, Brick (twice), Cones (three times), Vano (sic), some dimensions given, (Bailey) The Bank of England, Plan and Section shewing the mode of Construction of the Dome of the Rotunda


Soane office and Soane


Drawing 15 shows the use of paving brick, hollow bricks (or cones, as Soane refers to them) and stone in the construction of the Rotunda. The drawing shows seven stepped courses of stone strengthening the springing point of the dome. Square iron rods, connected with single links, were sunk in the stone to bind the material together. The inscription in drawing 15 indicates that the second stepped course of the springing point should be at a height exactly between the base of the lunettes and the peak of the dome, points labelled respectively D and B. From the springing point, the dome was constructed of alternating rows of three courses of paving bricks and four courses of cones.

The cones and brick provided a fire-proof, yet light, construction material. The cones were square and closed at one end, but basically circular in cross-section with the other end containing a small opening. Hollow bricks were used in Roman buildings for light-weight courses in domes and arches, and their popularity was revived in France in the 18th century. The cones were also employed in the vaulting of the Bank Stock Office and the Consols Transfer Office. It was the first time such construction had been employed in an English public building. For more on cones, see M. Richardson & M. Stevens (ed.), John Soane architect: master of space and light, Royal Academy of Arts, 1999, p. 237, cat. 145-146 and S. B. Hamilton, 'The History of Hollow Bricks', Transactions and Journal of the British Ceramic Society, vol.58, 1959, pp.41-43. See (SM) M 609 and M 610 for full scale terracotta models of the cones.



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Sir John Soane's collection includes some 30,000 architectural, design and topographical drawings which is a very important resource for scholars worldwide. His was the first architect’s collection to attempt to preserve the best in design for the architectural profession in the future, and it did so by assembling as exemplars surviving drawings by great Renaissance masters and by the leading architects in Britain in the 17th and 18th centuries and his near contemporaries such as Sir William Chambers, Robert Adam and George Dance the Younger. These drawings sit side by side with 9,000 drawings in Soane’s own hand or those of the pupils in his office, covering his early work as a student, his time in Italy and the drawings produced in the course of his architectural practice from 1780 until the 1830s.

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