Tuesday, April 17, 2018

The Baptist Church of Streetsboro, Ohio



This is the Old Baptist Church at Streetsboro, Ohio, built about 1820.




Here are the HABS drawings.


 I wondered about its geometry. What framing traditions had the master builder brought with him to Ohio?
It looks linear, simple, obvious. Is it?



I explored the plan and elevation. While many forms of the Lines created by circles and squares worked pretty well, nothing quite fit.  
I went back to the basics, the construction: What did the carpenter do? In what order?


He was asked to build a church about 'so big'  - here about 36' x 50'. He laid out a rectangle using the 3/4/5 Triangle.  The HABS drawings are blurry and tiny. The dimensions appear to be 38'-4.5" wide by 51' long,  3 units wide by 4 units long. (The length is about an inch too short.)

The triangles are ABC and ADC. They could also be ABD and BCD. The 2 layouts cross in the center.
The carpenter could check his diagonals, just as workers do today. When they match the floor is square.




 The bents for the frame were naturally the same width as the floor. It seems possible that the framer used the floor of the church for his layout. I had seen this in an upstate NY barn. I wrote about it here: https://blog.greenmountaintimberframes.com/2014/12/04/geometry-in-historical-frames-a-guest-blog/

The elevation of the front of the church was 2 squares wide. But the pediment did not come easily from that form - slightly too big.

However when I laid out the frame based on Lines laid on the inside edge of the sill and posts, everything fit and the peak of the bent, the location of the ridge of the church was the center of the rectangle. So simple, so easy!


How was it to the framer's advantage to lay out the frame from within the frame, not outside?  
He needed at least 3 bents . He needed consistent marks for lengths and widths of all members and for each mortise and tenon. The Lines laid inside the frame would not be disturbed while the frame was laid out and marked. The timbers could  be moved off the floor to cut the joints; another bent could be laid out. 
 Modern framers using timber and dimensional lumber stand within their work, measure, mark, and check from inside. Then they cut the lumber someplace else. Why not this earlier framer too?




After the bents came the walls and the windows.
The spacing of the windows and their width comes from the rectangles that are within the original larger rectangle. 
The green lines are 2 of those rectangles, the dashed lines with arrows on the left show the window frame locations.  The green dashed line with an arrow on the right ( top left) is the width. 

The outside dimensions of the church plan seem to have been used to place the windows. This makes sense: the wall needed to be flush with the outside of the posts. Pockets for the studs would be cut in the sill and plate in relationship to the outside surface.

  



The geometry of the bents determined the shape of the facade, the height of the pediment. The front elements of the church - the  pilasters and a grand door -  were designed after the frame. The front window were in place, therefore the pilasters needed to be equidistant on each side.
The door went in the middle, that's custom. Then there was the left over space in between. (See more about this below.)





The framers also had to provide support for the steeple. As I have no drawings of the side elevations, nor do I know the location of the bents. I do not know quite where the steeple sat: directly on the front wall? a few feet back?  I would assume a bent supported the front and back walls of the steeple. The diagrams do show how the width of the tower and the size of the clipped corners were determined: it was a square with its corners cut off.

The steeple grew from the proportions already in use for the church itself. The 2 rectangles made up of the 3/4/5 triangle were laid out.


Look at the left side rectangle first.
The lines of the Rule of Thirds*  - the diagonal and the line from the upper corner to the middle of far side cross under the steeple outer edge.
The lines cross just above a pilaster; the dashed red line with arrow labeled A locates the inside of the tower wall.

Now to the rectangle on the right side: On the right if the rectangle is divided into its 4 internal rectangles, the center of the small upper left rectangle determines the outer edge of the tower front corner. 
The cross sections of the tower were drawn on the original HABS drawings. They show the clipped corners. 

This change from delineating the inside of the frame to the outside clapboard and molding of the church is probably due to who was in charge: the framer for the construction, the joiner for the visual effect, the finish carpentry.  The joiner was responsible for making that central left over space fit!


The door and the steeple use the square for layout and design, not the 3/4/5 triangle. This diagram is to remind us that the triangle is just one way of dividing the square, that it is part of the same vocabulary.

The next post will show the front door and the steeple.   








Saturday, April 14, 2018

Of Course Geometry is Magic!


I am often told that daisy wheels used in Practical Geometry are magic.  Here is my response

Yes, geometry is magic.

The technical word is 'apotropaic': these shapes are protective symbols.





The basic shapes of geometry are perfect. They never change.
So is it any wonder that we think these perfect shapes that we humans can not just imagine but also draw, are paths to the supernatural? Of course we see them as holy, sacred, mystical.






Consider:
A circle of any size always comes back upon itself. Its radius, diameter, and circumference are always in the same ratio to each other. If they aren't  - it's something else, NOT a circle.
 Pi (the ratio between the circle and its diameter) is real and easy to see. Its arithmetic equivalent is infinite; it has been computed to more than 1 million digits with no end yet. (Google the number, just for fun!)

A triangle with sides 3, 4 and 5 units in length always has a 90*, square corner - seen here on the lower right side.


The square is always made up of 4 sides of equal length with 90' right angles. If any of those definitions is not present, it's not a square.







These shapes are part of each other: Here I've drawn a circle, some of its triangles, the squares that come from it.  These are the simplest forms, combined they can become endlessly varied and complex.





Geometry is science. On the grand scale geometry is the double helix of our DNA, the rotation of the planets.
It is a basic in our natural world, the small scale: the bee's honey comb, the crystals in a geode, the reflection in a mirror, the ripples of a pebble in a pond.
The Golden Section seen in the sun flower and conch shell is the expansion of these basic forms.

Too many of us found only relentless logic in our high school geometry class. We didn't twirl compasses, make daisy wheels, stars, hexagons, pentagons, octagons... using just arcs, points, and lines.
We rarely delighted in learning the magic of this world of patterns, proportions, rhythms that we are part of, that does not need words or numbers. Ionic volutes, daVinci's man, the tile in the Alhambra didn't grace our walls.


Practical Geometry is the use of geometry for construction: the arch of a Roman aqueduct or the cantilever of a suspension bridge, the vaulted ceiling and the rose window of a cathedral, the timber frame of a barn, the placement and size of architectural elements. It was used to build the pyramids, noted in the Bible. It is ancient, now mostly forgotten due to the Industrial Revolution.


















I study and blog about this practical geometry, part of our heritage which we no longer perceive, to help us recover it.
I hope we will learn again to see it and use it.





For more on this c. 1830 house see: http://www.jgrarchitect.com/2014/09/how-to-construct-square.html

For the use of geometry in the past several thousand years see: http://www.jgrarchitect.com/2017/04/the-bible-and-vitruvius-know-about.html

Monday, April 9, 2018

A Little Bit of the Geometry of MIT





 This is the curtain wall of the Mass Ave entrance at MIT,  the Massachusetts Institute of Technology, Cambridge, Mass.
The picture arrived in my mail box last week.



Immediately I saw the geometry. I knew what geometry the designer used and how it was manipulated.





I am currently writing three separate posts for this blog, one for my local blog. None has quite come together. Each has parts which require more drawing, thinking, and better choice of words.
Frustrating.
Then the latest MIT mailing to alumni/ae showed up with this picture.
I laughed. I walked beneath that wall of glass and columns for 4 years. In that time I paid a lot of attention to how we used the space it sheltered, how the shape and size of that 'entrance' directed what we did. The curtain wall was not part of my thinking, although the light it allowed into the rotunda was.
The wall's pattern, rhythm, proportions - or even just the idea that it was geometry - was not part of my analysis, nor was it ever alluded to by others. 


Here is the pattern.
Upper left : A square and its diagonals.
Upper middle: The circle that comes from using the diagonal of the square as the circle's diameter.
Upper right: The square that fits around the circle.

How the pattern grows:
Top row: Overlap a circle of the same size, so that the perimeter of each circle touches the square inside the other.
Second row: This pattern can grow sideways as well as up and down.
4 squares on the right: Once established leave out the circle, continue the squares, add the diagonal, horizontal, and vertical lines.


The pattern could have started with the circle and the 2 squares fitted around it.
Using the circle as the unit  - the 'module' or 'diameter' in classical terms - is the traditional way to begin a design. (See Palladio through Asher Benjamin.)

From a photograph I cannot judge the diameter of the column.  Does it taper? have entasis? The pilaster in the corner on the right appears to be the same width as the unit I chose: the original square.
If instead the column is the unit, the module,  the circles of the curtain wall might be 3/4 or 2/3 of the module.

I have been told that the main buildings at MIT - dedicated in 1916, designed by William Wells Bosworth -  were designed using geometry. The drawings of those buildings would be well worth studying.

Practical Geometry has become an integral part of how I see buildings.  I was surprised to find that it has become a practical design tool for me as it was for those who used it for construction.

Meanwhile, this little bit of geometry was just plain fun.