Geometry of the Cobb-Hepburn House, Part 3, front elevation

Here's the  Cobb-Hepburn c. 1780, in Tinmouth, Vermont, as it was  being dismantled last winter.

This front elevation feels bare and stark, less  sophisticated than similar houses built at the same time  in New England.
The 4 closely paired windows on either side of the facade, and the wide expanse of wall between the windows and the door seems 'not quite right'. As I travel, though, I see the same spacing on other houses near by. Am I seeing a local variation? the same framer working on many houses?

The frame is well built even though it was completed in stages.









The geometry, however, is rudimentary.  The plan for the posts and beams begins with squares, crossed to create a rectangle. The distance they are crossed is based on the arcs used to lay out the square - one of the first manipulations of practical geometry that an apprentice would have mastered.

The first plan shows the posts and beams with the crossed squares in red. The second plan shows how the width the squares are crossed was determined by the crossed arcs - dashed red lines - of the squares. 

(The center beam is off set to allow the chimney to pass and exit the roof at its peak.)

Was the framer never taught the geometry? He was capable of quality timber framing; he must have served a apprenticeship. Was his training interrupted by the American Revolution?
What he uses here are only the very elementary forms of practical geometry.



Here is the first page of  Biddle's Young Carpenter's Assistant. published in 1804. Biddle wrote his book for carpenters like the man who framed this house.
To see the bibliographic information about Owen Biddle's book please see the links at the end of this post.

After explaining how to make a drafting board, fix paper upon it and make a T square  - A,B, and C,  - Owen Biddle lays out solutions "to some of the most useful geometrical problems, which every Carpenter ought to be acquainted with."   
E: how to raise a perpendicular,  F: how to let fall a perpendicular, G:how to add a perpendicular at the end of a line.
And then H:  which I have marked with a red square 
how to layout out a square.
 I shows how to draw a 3/4/5 triangle which will always have a right angle. J  shows how to divide a circle into 12 equal parts.

Very simple work with a compass - and the geometry used in the design  of the Cobb- Hepburn House.




I have labeled the floors, the rooms, and the windows and door on the frame for easier understanding.  





The floor plan used the intersection of the arcs  of the square based on the width of the house for the placement of the interior beams ( BII and BIII).
To read the 2 previous posts which discuss this please see the links at the bottom of this post.

The front elevation uses the same geometry - the intersection of the arcs derived from the height of the house is both the edge of the posts for BII and BIII and the top of the 2nd floor plate. See the black dots where the arcs cross.

The framer next needed to place the windows and the front door. He 'crossed' the rectangles (BI to BII on the right, BIII to BIV on the left) on either end of the front wall. They cross in the center of the shape, which is also the 2nd floor plate. Upstairs and downstairs windows are symmetrical to that  crossing.

 I have outlined the right side with a red dashed line and added the diagonals.

Then it was easy for the framer to 'cross' the lower half of the rectangle. I drew it with black dashed lines. Where the red diagonals and the black diagonals cross is the center of the window frames.

The location of the door is similarly found by dividing the left over center space in half.    

http://www.jgrarchitect.com/2015/06/geometry-for-cobb-hepburn-house-part-1.html
http://www.jgrarchitect.com/2015/07/geometry-of-cobb-hepburn-house-part-2.html

Geometry of the Cobb-Hepburn House, an aside for skeptics

For previous posts on this house please read
http://www.jgrarchitect.com/2015/02/baring-bones-of-house.html
http://www.jgrarchitect.com/2015/06/the-cobb-hepburn-house-frame-tinmouth-vt.html
http://www.jgrarchitect.com/2015/06/geometry-for-cobb-hepburn-house-part-1.html


Here is the basic geometric shape used for the Cobb-Hepburn House.






When the house was built in 1780, the town of Tinmouth was less than 10 years old. It was the frontier. Paper would have been precious, not generally available for drawing house plans.


The master framer probably used dividers to layout the frame. We can see that he used them to draw the 2'  off set marks on the posts. Look to the bottom right of the post - 2 half circles above a line.

Sheathing was commonly used for diagrams.
I describe one such board found in a barn here:  http://www.jgrarchitect.com/2015/01/a-barn-and-its-daisy-wheel.html

Click the pictures to enlarge them.




25 years later when paper mills had become common, pattern books were popular teaching tools - beginning with basic geometry.


Here is Owen Biddle's Plate I in  Biddle's Young Carpenter's Assistant, 1804:


A and B are illustrations of how to attach paper to a board. C is the T Square.
(E,F,G are diagrams for perpendicular lines and right angles.  J is a 3/4/5 right triangle.K is the circle defined by 3 points not on a straight line.)


Just under the T Square is
H -  the layout of a square using the length of one side.


Biddle describes these engravings as " some of the most useful geometric problems which every carpenter ought to be acquainted with."
He explains that a student should have "a bow-pen or compass". 






 Asher Benjamin's  The American Builder's Companion, 1806, Plate II

has similar diagrams on basic geometry for carpenters.

All figures are explained on the accompanying page.
Fig.  12  is the same diagram as Owen Biddle's  H.

Benjamin writes in his Preface to the Third Edition:
"I have first laid down and explained such problems in Geometry, as are absolutely necessary to the well understanding of the subject."
He begins with

                           Plate I.
                  Practical Geometry.
                       Definitions. 

GEOMETRY, is that Science which treats the descriptions and proportions of magnitudes in general. 











Peter Nicholson's Guide, first published in 1792, in England, begins with geometry. It was updated and reprinted many times in London, New York and Philadelphia.
In his Preface  Asher Benjamin writes that he is "indebted to P. Nicholson's excellent books".

Figure 2 matches Benjamin's Fig.12 and Biddle's H.

This a a print of the actual page, Plate 3 - wear, age spots, and water stains included - in the 10th Edition, 1830.

I have the book in my library - on a long term loan.

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I  have written this post because of the skepticism I encounter from academics as well as craftsmen.
The use of geometry in construction is often viewed as somehow made up. I suggest doubters read what the master carpenters themselves wrote.


Owen Biddle, Biddle's Young Carpenter's Assistant, originally published 1805, by Benjamin Johnson, Philadephia. Dover (2006) unabridged republication, Dover Publicatons, Inc., Mineola, NY

Asher Benjamin, The American Builder's Companion, first edition published 1806, This print taken from the 6th Edition, 1827; unabridged republication by Dover Publications, Inc., 1969.

Peter Nicholson, The Carpenter's New Guide: Being a Complete Book of Lines for Carpentry and Joinery, Treating Fully on Practical Geometry... 10th edition, John Griggs, Philadelphia, 1830.

Geometry for the Cobb-Hepburn House, Part 1

When does geometry enter into the design and construction of a building?
Not at first.
Only when the basics are answered can layout and design begin, can geometry be considered.

The design of any building begins with need, ‘What?’ and ‘Why?’.

Next comes, ’How big?’, ‘Where?’

Then, ‘What material?’, ‘What will it look like?’  

Of course people often start with the vision, what they want the space to look like, materials they hope to feature. They may focus on a specific use for the space.

Sometimes they just begin with ‘Bigger than this!’ The planning then must cycle around to answer the other questions.

 

The Cobb-Hepburn House began with most of those questions already answered.

About 1780 the Charles Miles family needed a house on their land in Tinmouth, Vermont.

The house would look like houses they knew: a 2 story box with a gable roof and a center chimney, with a layout that was also familiar: a hall, a parlor on the front and a kitchen with service spaces behind. 

Here is their house after the modern siding was removed. The original house was probably not painted. It would have had small paned windows and a larger chimney.

The house would be framed of wood of which they had plenty. The foundation and chimney of stone – which also ‘grew’ right there. The frame would be 4 bents long and 2 bays wide.  

14 feet square +/- seemed good sizes for the Parlor and Hall. The space for the chimneys needed not be as large.

Here began the geometry.

Please read left to right. I have shown in the first 5 diagrams 2 points for each straight line. After that I have assumed the geometry is reasonably clear. I have also added a description even though I often find it easier just to read the drawings. 

1 -- The width of the house was laid out: 28’-6”: the length of the first bent.
 Just a line:  A -B

2 and 3 -- A square was drawn, using the line as an arc:  A -B - C - D
All the sides are equal.

E marks the intersection of the arcs.

4 -- Diagonals were added: F is the center.

5 -- The square divided in half both ways: the second bent. 

6 -- At E a vertical line was drawn: the third bent.

7 -- E is the center of the second square. The length of the sides of the square could have been stepped off to match the first square or laid out with geometry.

The fourth bent is the right side of the 2nd square.   

8 -- is the plan for the house, showing the locations of the posts - almost.

The as-built plan for the Cobb-Hepburn House, shown here, is not quite symmetrical. 

Here is the plan showing the posts and  beams for the 2nd floor with the 2 crossed squares in red.

I have seen the use of 'Crossed Squares' in many New England floor plans.Before I explored the geometry of this house I had not seen layouts use the intersections of the arcs as determining dimensions.

The framer used his intersections as the outside of the post location for the center bents. He seemed to set the center posts and beams back about 8" so that the chimney could more easily exit at the ridge of the roof. 

Here is an elevation of the bents from front to back for the house.
It fits within a square.

If the square is divided into its 4 smaller squares and the arcs of the length of the smaller square are drawn the intersection is the location of the top of the plate - see the green square on the upper left side and intersection.

Once the height of the house frame was set, the rafters could be laid out.
The second floor location was determined very simply: the top of the beam was located at mid point of the distance from the first floor to the plate  -  shown with a dotted green square on the lower right side.  

In both cases the framer used his intersections as the outside, not center line, of his beams.

The elevations of the house used the same geometry. That's next.

  

The Cobb-Hepburn House frame , Tinmouth, VT

Here is the Cobb-Hepburn House coming down.

Glenn Tarbell recorded its dimensions as he and his crew dismantled the frame this past winter. I drew the framing diagrams. My measured drawings of the house before de-construction served as a reference.

The drawings tell a lot about how the house evolved.

Local records show that Charles Miles came to Tinmouth from western Massachusetts. He built this house about 1780. When he moved to Ohio about 1810, he sold the farm to Amos Brown. In 1821 Brown sold it to his son-in-law, Edward Cole. His daughter, Jane Cobb, inherited the farm and house when Cole died in 1852.
Hod Hepburn was the last owner who lived in the house. After he died the new owner asked Green Mountain Timber Frames to take down the house.
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The house is 28'-6" wide by 39'-0" long, 2 bays (3 bents) wide and 3 bays (4 bents) long.
Its layout is derived from some of the earliest houses built in colonial New England

Center chimney floor plans were rarely built in seacoast New Hampshire and Massachusetts after 1760.  However, the first floor plan often appears in 2 story houses in New Hampshire and western Massachusetts up to 1770 and is a common plan for 2 story houses in Vermont through the 1840's.

The drawing is by William Lawrence Bottomley from his introduction  The Architectural Heritage of the Piscataqua, John Mead Howells, Architectural Book Publishing Company, Inc. 1937. His 10 page essay is one of the best introductions I know on early construction on the New England Seacoast from Salem, MA, to Portland, ME, .

Here is the probable floor plan for the Tinmouth House. I have labeled the rooms to match Bottomley's drawing.

The kitchen and the  pantry/dairy had been divided into smaller spaces by the time I measured the house in 2015. The other rooms still existed.
The first floor joists and sills were too rotted to be saved. The actual location of the original fireplaces is educated conjecture. A bake oven may have been beside the kitchen fireplace - we uncovered a mantle and cabinet door set in that wall.



The frame is massive, 10"x 10" posts rising to 10"x 14" and 10"x 16" gun stocks. The beams are 6"x 9", the plates 12" x 9". This is the 2nd floor SE corner seen from the 1st floor.
The roof rafters are of similar heft. The basic house frame was erected all at one time. Completing the interior frame took about 50 years.

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The way the framer set back the longitudinal center bent -  about 12" from the center - allows the chimney (drawn in red) to rise through the roof at the ridge.



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The frame for the north wall has missing and added studs as well as blocked windows, showing  how the house was changed through the years. The original 1st floor windows were directly below those on the second floor.








The west wall framing also shows window openings where we found no sash.
A door was added at some point and then closed off. A stud pocket remains in the beam above.









Empty joist pockets at the stair opening in the front hall indicate that the frame was reconfigured to allow space for the narrow, steep stair to the 2nd floor.




The second floor joists were made at the same time as the original frame.

The  Parlor, Hall, Bedroom and Kitchen joists are regularly spaced. The pantry/dairy joists aren't.
Quite a few of the joists have bark and wane; those above the parlor and the pantry/dairy are more logs than hewn.
The larger space between joists beside BII may indicate a stair.



Here is a possible explanation:


Charles Miles framed the house. He finished the Hall, Parlor and Kitchen; the Bedroom (which was usually reserved for the infirm or new mothers). Then he ran out of money, time, or energy. He finished the last joists with rougher wood. His family lived on the first floor.
Living in a partially finished house was not uncommon. Sections of a house were often used for storage and then added into the living space, just as we today add dormers to attics and insulation to  porches.



The attic framing was a different pattern: joists 2'-0" oc with intermediate 12" x 9" plates.
The joists all match: 3"x 6", cut by a sash saw at a mill.
The stair was relocated to where we found it.

As the frame was exposed we saw that bedrooms #1 and #2 were once one room, that bedroom #4 had neither lath nor plaster while the other rooms were finished.



Which owner installed the attic floor? The answer might depend on when sawn joists were readily available from a local mill.


The photograph shows the attic floor joist pattern. The window to the right had been blocked, but its outline was visible in the plaster wall. The window to the left was not original:the cut stud above and the lack of a stud on the left side were the signs of later construction.




Probably the Coles eliminated the fireplaces. Cast iron stoves were being manufactured in the 1820's.They were widely used by 1840.

 After stoves came central heat.We dismantled a modern cement block chimney serving a furnace and a modern wood stove.
Soot and char on beams implied that the framing around the chimney coincided with the installation of wood stoves.


For views of the house as dismantling began please see the previous post: http://www.jgrarchitect.com/2015/02/baring-bones-of-house.html