Friday, June 14, 2019

Corn Cribs for the Indiana Barn Foundation Workshop and Keynote

July 19-20, 2019, I will give a workshop and the keynote address on Practical Geometry for the Indiana Barn Foundation at the Oakwood Retreat Center in Selma, Indiana.
Their website is :

The picture they used for their announcement is the one I use on my website: It's a farm house north of Boston built about 1830 which was designed using a wonderful combination of circles and squares. I hadn't planned to include it in the talk but now think, of course, I will.

One post about this house is here:

I might have chosen this picture of my corn crib as it is a barn out-building - and because it is red!

My post about the corn crib here:

2 more corn cribs will be part of the lecture and probably the workshop.
They are from different construction traditions in different parts of the States. utilitarian buildings, built without frill, their forms easy to understand and read. They all use geometry differently.

The front of the Knight corn crib in Flatbrookville, Sussex County, NJ, shown here, is one of 3 HABS photographs of the crib. taken in 1969.

This is the quote which accompanies the photographs and drawings.
"Within this farm group that developed between 1826 and 1910, two significant structures are the corn crib and hog barn. The corn crib is an excellent example of early corn cribs in the Delaware River Valley, featuring a frame that is hewn and pegged."
This corn crib in New Jersey is therefore about the same age as mine in Vermont; they are not the same.

Here are the HABS drawings.

 It is so different from  my Vermont corn crib that if the sides did not slant I would have thought it just a shed.

The layout is governed by its width. The posts are placed  by 2 red squares and the arc of the squares' diagonals.
The same sized  2 red squares and the arc of the diagonal determine the height of the crib and its roof.
A crew could lay out the plan on site with twine,
then layout the section of the crib on a framing floor with twine,  cut the frame and assemble it on site.

The slope of the walls is set by the square: the sills - noted in red - are located inside the lower corners of the square, the mid-plates - also red - are located on the outside of the upper corners. the slope continues up to the height of the upper square.  The red line on the right indicates that the height of the wall is divided in half by the center girt.
 The crib design could have begun with a line and its perpendicular. The line could be the width; the perpendicular could have been one wall. Then with twine the arcs - in red - could have located the posts - also in red.

The upper brace in the section falls on the point where the diagonals crosses the arcs of the side of the square - noted in red. 
I have seen this only once in New England. The center brace is on the line of the squares.
The lower brace is not located on the arcs. Instead it is centered between the floor and the mid-brace.

To see the HABS photographs and drawings, type the name and location "Knight corncrib... " into your browser.

Sunday, June 9, 2019


 June 9, 2019
subject to updating

This bibliography was first complied to accompany a lecture on Practical Geometry in 2016. It is now available whenever I present.

A list of books by and about builders and architects who used Practical Geometry; many are primary sources.
At the end are other sources, websites, and credits.
It does not include books I refer to in a specific post. For example: Audel's Carpenters and Builders Guide, Theo Audel & Co. Publisher, NYC, 1923, is footnoted at the end of that post:

A few are books on architectural history and technology which I reference regularly:  Bannister Fletcher's History and Knight's American Mechanical Dictionary.


Benjamin, Asher. The Country Builder’s Assistant, 1797, Dickman, printer, Greenfield, MA –
     reprint by Applewood Books, Bedford, MA.
                     *The American Builder’s Companion, 6th edition, RP &C Williams, Boston, 1827
Biddle, Owen. *Young Carpenter’s Assistant, published by Benjamin Johnson, Philadelphia,
Charles, FWB, The Great Barn of Bredon, Its Fire and Reconstruction, Oxbow Monograph 76,
     1997, Oxford Books, Oxford, UK.
Fletcher, Bannister, A History of Architecture on the Comparative Method, Charles Scribner’s
      Sons, NY, 17th Ed. 1967.
Gibbs, James. *Book on Architecture, London, 1728
                       Rules for Drawing the Several Parts of Architecture, printed by W. Bower for the
      author, London, 1732, ECCO print edition  
Green, Bryan Clark. In Jefferson’s Shadow, the Architecture of Thomas R. Blackburn, Princeton
       University Press, NY, 2006
Harris, Leslie. Robert Adam and Kedleston, The National Trust, London, 1987.
Knight, Edward H. American Mechanical Dictionary, Vol I, II, III; J.B. Ford & Co. NY, 1874.
Nicholson, Peter. The Carpenter’s New Guide, 1793, London; 10th ed., Philadelphia, 1830.
Palladio, Andreas. *The 4 Books of Architecture, 1570, translated and published by Isaac Ware,
      London, 1738.
Serlio, Sebastian. On Architecture, Lyon, France 1530, translated in1611, available on-line. 
       Translated by Vaughan Hart and Peter Hicks, 1996, Yale University Press, New Haven
Shaw, Edward. *The Modern Architect, Dayton & Wentworth, Boston, 1854
Smith, Laurie, The Geometrical Design of St. David’s Cathedral Nave Ceiling, A Geometer’s
      Perspective, The Geometrical Design Works, 2017, printed Exeter, UK.
Vitruvius, Marcus. *The Ten Books on Architecture, c. 10 BCE, translated by Morris Hicky
      Morgan, Harvard University Press, 1914.

*Reprinted by Dover Publications, Inc., Mineola, NY

     HABS drawings, Library of Congress, Washington, DC
     Denison Bingham Hull, Old First Church, Bennington, Vermont, c. 1935.
     James Platteter, barn frame for Green Mountain Timber Frames, 2014
     All others: Jane Griswold Radocchia
Web sites: (you are here!)  and
for Laurie Smith: and  


Tuesday, May 14, 2019

The Cabins on Magnolia Plantation in Louisiana

8 small brick cabins sit in 2 rows facing the Cane River in Natchitoches Parrish, Louisiana.
Built about 1845, each originally housed 2 enslaved families.
They were in use until the 1950's. Now they are part of the NPS  Magnolia Plantation. 

The red diamonds are the plates for tie rods added by the Park Service to stabilize the  walls.

When I was in Natchitoches, Louisiana, in April, presenting Practical Geometry workshops for, we explored the geometry of the cabins.  I had not seen the cabins yet so we focused on the geometry of the end elevation.

Cabins were utilitarian, built using ordinary construction. Studying these simple structures helps us understand what geometries the local carpenters understood and used.

The brick walls, fireplaces, chimneys, and hearths were made with local clay  - probably by the enslaved people who lived in the cabins. The cabins had dirt floors. Wood was reserved for plates, rafters, sheathing, and doors; the hardware made by the plantation blacksmith.

I used HABS drawings for these cabins. Having not seen the cabins I thought the drawings might not be accurate. I was wrong. In the last 170+ years a lot of updating has happened, including floors, windows, replaced roofing.

The end walls are 2 squares wide. The size of the square was determined by the height of the cabin to the plate for the roof - see the arrows on the elevation.

The diagonals locate the ridge. The section makes this clear: the height of the square is the height of the brickwork.
The squares begin at  grade, not at the floor. The plate and the roof frame are above the square.

The diagonals of the squares becomes the radius for arcs; the point where they meet is the cabin's ridge.  Follow the  black  line and arc with arrows and the red line and arc with arrows.

The brick wings allow the roof to be set between the ends, not overlap. The bricks are turned, the ends flat, to make the wall weatherproof and neat. The end windows are not original.

The plan laid out the inside edge of the brick walls. This is common and intelligent; the  
line is there as a reference as the wall is built.
The cabin room is a 3/4/5 rectangle - see the left side.

The location of the hearth and fireplace is determined by the square - see the right side in the plan. This was not easy to check on site as the floors were added, but as  a hearth is an essential part of a fireplace, especially one used for cooking, this makes sense.


The window on the long wall is centered on the floor plan 3/4/5 rectangle. It is also called out by the geometry of the side elevation. 
I have drawn the square on the left with its sides all 3 units. On the right side is the 3/4/5 rectangle with its units. 
Below I have overlaid both. 
The black squares mark the location of the window and the beginning of the masonry for firebox and chimney. The red 3/4/5 rectangles mark the width of the window as well as crossing to lay out the location of the firebox and chimney. 

3/4/5 rectangles ensure a square, true, brick wall. This use of the 3/4/5 rectangle and square together is not a geometry I've seen before. The records show that the enslaved people at Magnolia came from the 'Gold Coast', now Ghana, along the Atlantic Ocean. Possibly they brought this geometry with them.

The use of the diagonal of the square to locate the ridge was also used, in a slightly different way, for a barn in upstate NY. See This is the floor plan - a  root 2 rectangle - with the end elevation coming from its geometry.

Many people migrated north of Albany after the Revolution, included Huguenots who has come from France to  Pennsylvania and New York, in the 17th Century. Could this geometry be French in derivation?

The website for Magnolia Plantation is: