Backfilling and the Future

Today we will backfill all our units.

The research now transitions into the lab and the library. The blog won't end here. Over the summer, we'll make more entries about the other excavation units. Perhaps some of the students will finally write for the blog and post photographs. Jessica and I will keep updating the blog all next year during the analysis and write up, as we complete artifact analyses, lab tests, and experiments.

These are some of the overall site pictures that we took before sunrise yesterday, when the City of Parowan lent us a cherry-picker bucket truck.

This picture shows the relationship between the kiln, the cellar, and the northern workshop building.

Here is a detail shot of the kiln, showing the fully excavated firebox, flue, and outline:

Another overall shot that shows the relationship between the opening of the trench that leads to the firebox and the opening of the workshop basement door:

A great picture of this great crew on the last day, just before we broke up for our final jobs:

Pictures and Holiday

Today marks just about half way through our field season!  We are in the middle of a break and the students are on holiday, driving among the beautiful landscapes of southern Utah.  We start excavation again on Friday.  I thought this was an opportune time to put up a few pictures of the site showing the total extent of our excavations.  

This picture is of the first kiln we discovered, showing the full extent of recent excavations. Frank and Brandon opened a second unit adjoining the south side of the square that Renée and Samantha have dug.  They have exposed more of the kiln's floor, but we are puzzled because they have not uncovered part of the exterior wall and flue system, and we haven't found the fireboxes or kiln door.  We have more digging to do before we fully understand this kiln!  

The next image looks south over the 6 meter long trench that we've dug north of the first kiln.  You can see a pair of stone foundations that Samantha, Mark, and Mike have exposed.  The foundations are substantial and the artifact preservation in the units is extraordinary.  I have a theory about the purpose of this building, but I'm withholding speculations until we have a little more evidence.  

The final photo shows an overall view looking south toward the mountains.  The wide angle lens distorts the image, making the mountains look small and the site narrow, but it captures the arrangements of the excavation units.

In my next post, I'll describe how the pieces of the puzzle are starting to fit together. Readers might notice that the students have been signing up as coauthors on the blog.  I hope some of them will start making posts next week, telling what they've learned about their discoveries and the process and practice of public archaeology.

Math problem, Part 2

Several people sent me comments about my math word problem.  In the original post, I asked people how to calculate the diameter of a circle when I only had a chord.  I set up the word problem with this diagram of the kiln wall:

We thought about the problem a bit, but couldn't recall any formulas for a circle that didn't require one to know the radius, diameter, or circumference as terms of the equation.  I did remember that the solution involved making two right triangles along the arc.  While eating my peanut butter sandwich, I decided that I could use the two right triangles to get a quick and dirty solution.  I knew I could draw the two triangles at scale and cut them out.  Then I could use a set of circles drawn at the same scale and slide the triangles over the concentric circles until I found the best fit.  This sort of the way we calculate the rim diameters of ceramic fragments.

We all knew that our math friends would remember the equations, however.

Pete and Mark Dice phoned in an answer.  Pete promised to send me his figures by email.

C. Crosse commented on the blog.  She said, "Given that c is a straight line between two points on the circumference of a circle--X and Z--which is called the cord, the curved line would be called arc XZ. Assuming you know c (not XZ) and m--the height of the arc created by the chord--then the formula would be:

r = (m² + ¼c²)/2m

Pete Foss made a comment on the project Facebook page:

"I found a circle calculator here: 

http://www.1728.com/circsect.htm 

that says your kiln was 1.88 meters in radius. 12 feet in diameter."

He added, "Hooray for Google!"  

Indeed.  The page that Pete sent includes a useful illustration:

I'd still like to hear from one of my friends that are math teachers! We have marked out a circle of 12 feet on the ground surface. As we excavate more of the kiln, we will be able to get more accurate measurements.  Family oral history said that the kilns were "about 14 feet across" and that there may be three or four of them all in the back yard.  We'll see what we find out. 

May 28, 2009- update.

I have heard from my friend Kristin Z. Cook, who teaches math at a high school in Milwaukee. She ran the numbers and said: "I am assuming the perpendicular segment you drew bisects the 1.8-meter segment.  If that is the case, then I calculated the radius to be approximately 1.8759 m, the diameter to be 3.7517 m, and the circumference to be 11.7864 m."  She promised to scan and email me her a page that showed her work.  She is a math teacher, after all!

My colleague Steve Walton also worked up a solution, but not to be outdone by others, he formatted a diagram and included it in his email:

So there is pretty wide agreement that the kiln is between 12 and 12.5 feet in diameter.  Pretty close to the 14 feet diameter recorded in oral histories and given the inaccuracies of our measurements, we need to leave a little wiggle room in our conclusions.

If you are curious, here is how I figured out my estimate.  I drew copies of sets of right triangles using a scale.  The right triangles split the chord evenly in half.  I new that I could make a second set of overlapping triangles on a second overlapping chord, then line up both sets on a scale drawing.  If I projected their short side as in the drawing below, I knew they would intersect in the middle of the circle and allow me to measure the radius!  I always liked geometry proofs more than algebraic ones....

Kiln pics

We have dug about as far as we can on the kiln. Before we go any further, we must open up another unit to expose more foundation surface.

In these photos, you are seeing the kiln floor. Beneath the floor, on which pottery sat during firing, there is a system of arched or vaulted flues moving hot air as well as fire boxes where the Davenports could add wood or coal.

We will see.

I promise to write more about the other units soon.











Mobile blog post

We were right...

It is definitely the first pottery kiln.  A major discovery, since this is the first English style kiln excavated by archaeologists from the country between Denver and the Pacific coast of California.  Maybe even as far east as Tennessee, Minnesota, or Kentucky.

Renée and Samantha are still working to expose the arc of brick:

Sam is happy to be cleaning the sidewalls in preparation for a photo!

We spent lunch talking about how to calculate the diameter of a circle when you can only measure a chord along the arc.  This is a particular question for the mathletes out there.  I've worked out a solution in the tradition of pragmatic field archaeology, but if somebody thinks they can be more accurate, let me know!

The chord is 1.80 meters long measured from the outside edge.  Making a 90° angle and measuring at 0.90 meter gives a triangle side that measures 0.23 meter.  A real world word problem!

email or post your solution!  Show your work for partial credit...

A Sharpe Kiln

As I have written in the past, I've been corresponding with archaeologists and researchers in England to get ideas about what Thomas and Sarah Davenport might have known about pottery making, kiln building, clay processing, and other related skills.  I need to know as much as I can about this in order to judge the local adaptations that the Davenport's created to Southern Utah's new landscape.

Most recently, I was tracking down excavations of pottery kilns in the Derbyshire region.  I found the website of the Sharpe's Pottery Museum that included a mention that the kiln had been archaeologically excavated in the 1990s.  Philip Heath answered my email inquiry.  Mr. Heath is the Heritage Officer for the South Derbyshire District Council.  He has put me in touch with the archaeologists involved and also sent me a digital image of one of the interpretive panels at the site.  He said that I could post the image on the blog, and more information about the Sharpe's Pottery Museum is on their website at:

http://www.sharpes.org.uk/

Thomas Sharpe established his pottery in 1821.  The Sharpe's Pottery operated as a company, making Mocha ware and Rockingham-style ceramics. These pottery types are also known as yellow ware because the stoneware body has a strong to pale yellow colored paste.  These ceramics were often decorated with annular banding and the dendritic patterns for which Mocha ware is famous.

The kiln photo above shows one possible configuration with which Thomas may have been familiar.  The picture above shows the archaeological excavation inside the standing hovel-- the bottle-shaped chimney that surrounds a kiln in most English traditions.  In this case, all the bricks were removed, leaving only the stained soil to mark the structure itself.  While a later foundation wall cuts right across the kiln foundation, you can still clearly make out the circular footprint of the kiln and most of the fireboxes that surround it.  In the English tradition, the kiln is round and the fireboxes are generally below the floor surface and evenly spaced around the outside edge.

Academic industrial archaeologists used to talk about "ethnic" or "national" technological styles, which was a way of explaining why the English immigrants to Utah built round, up-drafting kilns, while the Danish immigrants built rectangular, cross-drafting kilns.  I look forward to talking with the students about this and making more posts about this in the future.