Timber Framers Guild Conference, Manchester, NH, Aug 7-10, 2014

I will be speaking at the TFG  Conference, Friday afternoon, Aug. 8, on geometry in the  States, 1683  through 1850. I will begin with the First Period houses in Topsfield, MA, and end with the 1850's dismantled railroad shed. I will  use the diagrams and photographs from this bog.



The day before, Aug. 7th, the TFG bus tour will stop at the Sandown Meeting House. I will be there to explain the geometry.  I will have the diagrams. I will also encourage people to stand in the pulpit and sense the space. The attic will be open. Will Truax will be up there in the trusses with windows and a roof hatch open. A permanent steep stair leads up to the trusses and a board walk is in place across to a now missing chimney, so it is reasonably safe. No one should go through the 250 yr. old plaster ceiling!
The Sandown historians will be there as will First Period Colonial, Bob Pothier, the carpenter for the last set of repairs.






The recent workshop at Trillium Dell with Laurie Smith brought up lots of ideas and questions which I do not expect to answer before the talk.
Some of the issues are simple:What do we call certain recurring forms and geometries?  We need a common language.

Some more complex:
Is there any indication that the houses I am looking at  begin with circles which laid out that first square?
Were the master carpenters and owners whose houses I have laid out trained in the guilds in England? Is there a record that they studied geometry?
Am I seeing different geometries because of different framing systems? For example: the geometry noting cut lines, not center lines, for interlocked log walls in Virginia - or because the people came from different parts of England with different training? What about the Dutch? the Germans? the French and Swedes?

Am I seeing the length of a rod: 16 feet 6 inches, and not noticing? Laurie Smith finds it to be a common, basic dimension in England and Wales.
Have I missed it because I haven't been thinking about it? If the framers here were not apprenticed to someone trained in the ways of the old country would they have adopted another length?

The Timber Framers have suggested that people who might like to come only to my talk need not pay the fee for the whole day - which includes food as well as all the other sessions - but could simply make a donation.

Sandown, New Hampshire, Meeting House, 1773

UPDATE, July 31, 2025

I substantially revised this post on April 18, 2014.  

11 years later I am rewriting it again. 


Timothy Palmer is listed as the master builder of this meeting house, built in 1773. 12 years later he built the Rocky Hill Meeting House in Amesbury, MA., which I wrote about here:  http://www.jgrarchitect.com/2014/02/rocky-hill-meeting-house-amesbury-ma.html

I was curious to find out if the geometric language used to design the Rocky Hill Meeting House could be seen here as well.
I knew of the Sandown Meeting House but had never seen it.
Luckily HABS drawings of the Meeting House are on-line. This photograph is part of that record. I borrowed it through wikimedia. A detailed history with photographs can be found at http://www.colonialmeetinghouses.com/mh_sandown.shtml.


I thought I'd just see what Timothy Palmer built, and how he evolved as a master-builder - simple.
Instead I found a larger fascinating history.
 But first: the geometry of the Sandown Meeting House.

Start with the simple geometry, the square.
Here is the front elevation - 2 squares side by side. I've crossed the one on the left side with both diagonals, but only drawn one diagonal for the square on the right side. The squares determine the size of the front and the structural dimensions: they include the sill and the top plate


The window placement is also simple:
On the right side I have divided the square - see 'a-a-a-a' - in half vertically and then drawn the diagonals for those rectangles. The intersections are at the edges of the windows - see 'c'.  The windows themselves are 2 squares. See the diagonals in the window upper left corner.
Then I've rotated the square to show how the line determines the location and width of the entrance - see 'b-b-b-b'.

 

I have not yet figured out why the door is off-set. Maybe the space needed for the stairs to the balcony threw things off.
Note how the symmetry of the windows is so strong and the triangular pediment such an 'eye catcher' that one has to pay attention to see that the door really isn't centered! 




Where did Palmer begin his design? The church committee overseeing construction would have told him approximately how big to make the building. How did he determine his layout?

I think he began with the pulpit.
Here, as in the Rocky Hill Meeting House the pulpit with its sounding board is the centerpiece of the church. Not only is it ornate and dramatic, it surrounds, protects and presents the preacher and the Bible. The book would be laid out, open, on the lectern. And the lectern is precisely at the crossing of the squares.   (Here I think I need to add a picture of the pulpit.)

 One square begins on the right of the pulpit and extends to the left; the other begins on the left and extends to the right.

I have blacked in the columns as the design locates them. Here the lower edge of the squares runs through the columns which support the balcony. The center the squares locates the columns in the open space  - both, however, in only one direction.
The left and right sides of the squares are the locations of the posts on the north and south walls and the roof trusses above. See red lines on either side of the main aisle. 





The length of the diagonal of the square is also the width of the meeting house itself.  I have used that diagonal to draw a square inside the frame of the meeting house. It extends outside the building at the entrance and the pulpit. Where it crossed the outside walls is the line which determines the posts on each side of the central aisle. See the green square set as a diamond and its left and right green triangles.
The final columns are those on either side of the east and west entrances. The triangles noted in green also mark off the 2 squares on either side of the central aisle. When those squares are subdivided, the subsequent intersections determine the columns - see the small squares and their diagonals on either side of the left (west) door.

 The West Elevation - Interior shows Palmer again using the crossed squares. The diagonals are also the position of mortises in the roof trusses. The extension of either interior diagonal  lands on the top of the brace.






Timothy Palmer did not use circles with 6 points (the daisy wheel). He did use the square 'flat' and 'rotated', and its 8 points to design the entrance. I just needed to determine his basic length: the radius of the circle.


The first dimension I saw was the distance between the center of one pilaster and the other - the horizontal line in the middle of the circle. I deliberately white washed the extensions of that line to show the circle divided into 8 segments and the distance between the pilasters.
Then I realized that that length is also the height of the columns from the pedestal to the capital. Hmmm....
That length is also the radius of the circle that encloses the entry from the peak of the pediment to the bottom of the door.
The width of the pediment is determined by the circle's upper spokes. The height of the pedestals is set by the lower spokes. Perhaps Timothy Palmer's own history accounts for this.
He was apprenticed to Daniel Spofford, an architect and millwright in Newburyport, MA. Some records say he also learned shipbuilding  from Ambrose Spofford. He seems to have been responsible, at age 23, for building this meeting house. Perhaps he also built the pulpit.
His other responsibility was to span the open interior space of the church. He would have know what was necessary to frame a boat hull - which is in some ways an upside down roof.

At the Rocky Hill Meetinghouse he used other geometry: a circle with 6 spokes or petals: a daisy wheel, a much more complex double square, and the 3-4-5 triangle.
In 1792 he quit building churches and became a bridgewright. He built many bridges including 4 across the Merrimack River, and the Market Street Bridge in Philadelphia. For more information see Frank Griggs' excellent well illustrated article:  http://www.ce.memphis.edu/3121/stuff/general/timothy_palmer.html