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The Tuckahoe Cabin Geometry

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 This is the double slave cabin at Tuckahoe Plantation, Thomas Jefferson's childhood home in Virginia.
I have written about it before:  http://www.jgrarchitect.com/2014/06/cabin-tuckahoe-plantation-goochland.html


The simplicity of the cabin and its HABS drawing make it an easy building to use when I teach hands-on Practical Geometry.




The beautiful hand drawn lines and details of HABS drawings fascinate students. And they get a little history.
Here the elaborate paneled front door for the plantation house, its ceiling pattern, and columns are shown with the little, uncomplicated cabin.
Craft, wealth, slavery c, 1750,  are visible side by side.


Remember that you can click the drawings to enlarge them.





The cabin illustrates the Rule of Thirds.
Students unused to geometry can grasp the basics quickly as they discover the design simplicity of the floor plan.They explore the geometry of the elevations with curiosity, not in trepidation.

For a tutorial on the Rule of Thirds:
http://www.jgrarchitect.com/2016/10/practical-geometry-drawing-diagrams.html




BUT -  This is academic.
How did a carpenter actually use this knowledge?

I wasn't there. So, I am guessing? No.

I've read the written documents, 'read' the drawings that have no words - from that period and the more recent era of HABS. I've measured and documented these buildings, participated in repairing and framing them as well as their deconstruction.
I make connections to the old ways of laying out a frame from the way we lay out today using the same tools our ancestors had - a line, a square, a plumb bob, a pencil - and  a compass.


Here is a construction scenario for this cabin.

The carpenter plans to build a 2 room cabin with a loft, 2 doors, 2 windows, back to back fireplaces on this site.
The size is standard, each room about 16' x 16'. He either builds right here, or he uses a framing floor. In either case it is a flat, level surface. His geometry will establish his points and keep his frame square.
 He measures off 16' with twine, using his own handmade rule. He then stretches out his twine another 16-20 ft, pulls it taut.
He now has a straight Line.
Maybe he has chalk and snaps it, making a line.  Maybe he pegs it.
Modern carpenters snap and set lines regularly. We still call them 'lines'.


1 - On his Line he marks his first point (A).

2 - He chooses a radius and draws 2 arcs, one with its center at (B), one with its center at (C).  He now has 2 points where his arcs cross and can draw a line perpendicular to his Line.

3 - He chooses his dimension -  here, 16 ft -  puts his compass - perhaps a string with a knot at 16' -  at (A) and draws a semi-circle (D-E).
Now he has a new point (F). His cabin is now 32' long; its width is 16' (A-F)

4 - Using (F) as his center he draws another semi-circle.

5 - Then he draws 2 quarter circles using (D) and (E) as his centers. Where the arcs cross (G) and (H) are the upper corners of his cabin.

6 - He swings the other arcs, and now has 4 internal points in each room of the cabin. He marks those points.

7 - Just to be sure, he trues up the space by checking that his diagonals are equal (G-A, D-F etc.).

8 - The interior points give him the centers for the doors, windows, and fireplaces. The plan of the cabin is done.

The end elevation, or  the 3 bents of the frame:
 9 - He sets up the 16' square with its arcs.

10 - The interior points give him the location for the 2nd floor joists.

11 - The points also give him the center of his elevation. He can draw his Lines and use the Rule of Thirds to find the upper third of his square (J-K). 

12 - (J) and (K) mark the eaves for the roof. He extends the sides of the square, draws his arcs to find the upper corners ( L) and (M), adds his diagonals  (J-M) and (L-K). Ahh - there's the roof!







 The window in the eaves is placed and sized:













A carpenter before the Industrial Revolution would not need my description. He would have learned the geometry as an apprentice. If he needed a reminder he would practice a bit with his compass. He probably didn't have a drawing for such a simple cabin.

However, books with instructions to builders (not architects) did exist. Here are 2 examples.





Batty Langley in The Builder's Director, London, 1751, draws moldings "Proportioned by Minutes and by Equal Parts".  He writes that his little book is to be available to "Workmen" and "any common Laborer."

These window and door 'Weatherings' are all composed of squares and arcs of circles. Langely lays out the parts; the Workman can read the rest.





 Asher Benjamin in The Country Builder's Assistant, Greenfield, MA, 1797, says his book "will be particularly useful to Country Workmen in general".
 He assumes the Workman knows geometry.
Plate XXIX  says only
 "C, is a roof; divide the width of the building into 4 parts, one of which will be the perpendicular height. Divide Fig. D, into 7 parts,give 2 to the perpendicular height.
Fig. E, is intended for a roof to a Meetinghouse; divide the width of the building into 9 parts; give 2 to the perpendicular height; the ends of the Beams, a, a, are to be supported by columns."




My first post on Tuckahoe Plantation is here:    http://www.jgrarchitect.com/2014/05/tuchahoe-planatation-richmond-virginia.htm











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brico
44 minutes ago
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Some of this stuff is achievable by modern grid systems (the plan here, for example) and it's easy to be skeptical that carpenters actually used these techniques that seem so foreign today. But then she does something like place the window in the gable with arc intersections... boom, dead on. That's circle math for sure, not module math.
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Gentle Reminder: Still No Public Email

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LAP_logo2_940In 2015, I closed my public email address to preserve my sanity, though some would question whether I succeeded in my goal.

Lately, a lot of people have attempted to seek advice, feedback or whatever through my personal site: christophermschwarz.com and through help@lostartpress.com. I’m up to about five messages a day now.

Please don’t waste your breath, your fingers or your 1s and 0s. These messages are all simply deleted.

I know deleting them might seem rude. And some of you have told us how rude you think it is in long rants… which get deleted.

Trust me. It’s not you. It’s me. I had multiple public email addresses for 17 years and answered every damn question sent to me – no matter how odd or how much research it required. I helped lazy students with their papers on hand craft. I found links for people too lazy to use a thing called Google. I answered sincere but incredibly time-consuming emails from people who wanted to tell me their life story and get detailed advice on the steps they should take to become a woodworker.

And those weren’t even the ridiculous requests. It’s too early in the morning for me to even think of those.

It was all too much. I was spending hours each day answering emails. It cut into my time researching, building, editing and writing (not to mention time with my family). And then one message snapped my head in two. Out of respect for the individual who sent it, I won’t go into detail because he would be identifiable.

The email he sent was longer than my arm. It was going to take me hours to formulate even a half-a$%ed reply.

I deleted it. Then I deleted my inbox and my old email address.

So now I’m half-sane.

— Christopher Schwarz

 

P.S. If you really want to ask me detailed questions, the best way to do that is to visit our Covington storefront on the second Saturday of every month. I’m happy to talk to anyone about anything. I know some of you will whine that you are too poor to travel (while typing on your $2,000 computer…), but people have made the trip from almost every state in the country.


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11 hours ago
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Trump's presidency is the result of decades of structural problems in the US, not a brief Moscow campaign. If we can't or don't reckon with that, then Trump is the lighthearted intro to the much darker era that will follow him.

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Trump's presidency is the result of decades of structural problems in the US, not a brief Moscow campaign.

If we can't or don't reckon with that, then Trump is the lighthearted intro to the much darker era that will follow him.


Posted by pwnallthethings on Friday, November 17th, 2017 11:24pm


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Saturday Morning Breakfast Cereal - Specialization

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Click here to go see the bonus panel!

Hovertext:
People who say we'll become one with the machines should really specify the machines they're talking about.

New comic!
Today's News:

Tomorrow we will return to my low-quality scribbling. If you enjoyed Abby's style (you did), click here for more.

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brico
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jlvanderzwan
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This is now my headcanon Borg Origin story

Richard Sachs Seat Lug Survival Kit

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Keeping things tight is part of the task. Around here that includes the seat post. After 45 years at the bench, having tried countless brands and designs, my own is now a reality. My desire was to produce a seat lug bolt assembly whose quality and precision matched the frames I make. Not a part […]
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Should-Read: Ta-Nehisi Coates: Ta-Nehisi Coates has an incredibly clear explanat...

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Should-Read: Ta-Nehisi Coates: Ta-Nehisi Coates has an incredibly clear explanation for why white people shouldn’t use the n-word - Vox: "When you’re white in this country, you’re taught that everything belongs to you...

...You think you have a right to everything.… You’re conditioned this way. It’s not because your hair is a texture or your skin is light. It’s the fact that the laws and the culture tell you this. You have a right to go where you want to go, do what you want to do, be however—and people just got to accommodate themselves to you.

So here comes this word that you feel like you invented, and now somebody will tell you how to use the word that you invented. ‘Why can’t I use it? Everyone else gets to use it. You know what? That’s racism that I don’t get to use it. You know, that’s racist against me. You know, I have to inconvenience myself and hear this song and I can’t sing along. How come I can’t sing along?’... The experience of being a hip-hop fan and not being able to use the word ‘ni--er’ is actually very, very insightful. It will give you just a little peek into the world of what it means to be black. Because to be black is to walk through the world and watch people doing things that you cannot do, that you can’t join in and do. So I think there’s actually a lot to be learned from refraining...

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