James Gibbs was the Surveyor of the Work for the design and construction of St. Martin in the Field, Trafalgar Square, London, begun in 1722, completed in 1726.
His pattern book, On Architecture, published in 1728, had 150 plates. 7 were engravings for St. Martin's. He writes that Plate II is "The Geometrical Plan of the Church and Portico, shewing the Disposition of the whole Fabrick." (Introduction - i)
Plate III, shown here, is "The West Front and Steeple"
Many churches and steeples are included in Gibbs' book. Plates 29 and 30 show 6 images of steeples, all drawn for St. Martin's but not chosen. Plate 31 has 5 draughts of steeples for St. Mary le Strand.
In 1775, the Providence (RI) Gazette, writing about the Baptist Meetinghouse, comments on the use of the "middle Figure in the 30th Plate of Gibbs designs" * for the church steeple.
This engraving is the draught (the architectural drawing) of the Geometric Plan of that steeple. Gibbs writes that while steeples are Gothick, "...they have their Beauties, when their parts are well dispos'd, and when the plans of the several Degrees and Orders of which they are compos'd gradually diminish and pass from one form to another without confusion, and when every Part has the appearance of a proper Bearing." (viii)
The Master Builder for the Baptist Meetinghouse was Joseph Brown. How did he know what to do from those instructions?
He was not only a builder but an astronomer, a scientist and a professor. He knew his Geometry.
How would the parts be 'well dispos'd' or well ordered. That could refers to the pattern of 'base, column and wall, architrave' for each section.
Or it might be how the parts are all the same height. I have marked on the engraving where each part begins and ends. Each provides physically and visually 'a proper Bearing' for the next level.
How did the parts 'gradually diminish'?
Below each steeple on Plates 29, 30 and 31 is a cartouche, a diagram: the plan for each steeple, showing the outlines of each steeple part.
This is the diagram for the middle steeple which was copied for the Baptist Meetinghouse.The image in the book is 1.5" square. It is the size of the image Joseph Brown, Master Builder, would have worked from.
I have labeled the outlines of each part of the tower to correspond with my numbers on the steeple drawing above. (5) is the base of the 8 sided spire. The innermost circle is the cap where the weather vane is attached.
The parts layer one on the other following a diagram, a pattern - which I refer to as the square and
its circle. This geometry was well known. It goes back in construction
to at least the 7th c. in Constantinople. Serlio placed it on his
This variation of the square and its circle, uses only the diagonals and adds the division of the square into quarters. As the design has 8 sided Parts (#3 and 4) and an octagonal spire, perhaps this diagram was used.
Where the Lines cross the square locates a smaller square, rotated. And those Lines locate the next. They determine the size and location of each Part of the steeple
The diagram is not meant to be a working drawing. Instead it directs the builder. It does not matter if it is not quite accurate. When the builder lays out the work he will adjust and refine the shapes to fit his frame.
What happens when the first square is rotated - creating an 8 pointed star?
And the squares that fit inside that square are added? Drawn here in black over the first diagrams drawn in red.
The octagons of the Parts are laid out. Drawn on a framing floor the lengths for each wall would be easy to measure and set correctly.
It's done with just a length of twine and the knowledge of geometry.
The Providence, RI, Baptist Meetinghouse - with its steeple, drawn c. 1800. The image is now in the Library of Congress with the HABS drawings of the Meetinghouse.
* quote from American Architects and Their Books to 1848, ed: Hafertepe and O'Gorman, UMASS Press, 2001, Abbott Lowell Cummings' essay, The Availability of Architectural Books in Eighteenth-Century New England, p. 2.
The lower right corner of Sebastiano Serlio's frontispiece of his On Architecture: a cube with its diagonals, the circle and the next square that fits within that circle. As can be seen in the steeples drawn by James Gibbs, these circles and squares can grow in and/or out.
James Gibbs' diagram using Serlio's square and circle. It also 'works' and could have informed the design.
Currently, as I research, I think the 8 Pointed Star was easier and was more likely to have been used .
All books referenced without complete attribution are listed in my bibliography.