Thursday, November 30, 2017

A Colonial Clay Pipe Stem Fragment

The opening scene of the first episode of actor and author Mackenzie Crook’s comedy TV series Detectorists is set in a plowed field somewhere in Essex, England.  Our heroes Andy and Lance are working the field with metal detectors, rhythmically swinging them back and forth while listening through headphones for telltale pings signaling metal in the ground.  Lance suddenly stops, drops to the ground, digs out an object which he inspects with a jeweler’s loupe.  Andy asks what he’s found.

Lance:  Ring pull.  ’83.  Tizer.

Lance carefully puts the ring pull into a plastic baggie.  (Some context here:  What he’s found is typically called here in the States a “pop tab” or “pull tab” or, as Jimmy Buffett styled it, “Stepped on a pop top.  Cut my heel.  Had to cruise on back home.”  Tizer is a British red-colored, citrus soda.)

Andy:  What do you do with ’em?

Lance:  Bag ’em up, stick ’em on eBay.  People buy this shit.

Andy:  Sad tits.

Lance:  You said it.

That exchange captures the gently mocking, almost self-deprecating humor of this superb series.

For a couple of reasons, the Detectorists came to mind this past summer while I was on vacation at the North Fork of Long Island, New York.  Not much of a vacation actually as I was trying to cope with nasty back issues that kept me from looking much above eye-level without excruciating pain.  A friend, who is a birding authority, was visiting, so my wife and I ventured out with her to several of the nature preserves that dot the North Fork.  They vary greatly in quality but the impulse behind them is praise worthy.  Armed with binoculars, which I couldn’t raise to look high in tree canopies, I went birding.

The first preserve we visited was alive with birds even at midday.  Despite my clear limitations, in time I saw 14 different bird species including an Eastern Wood-Pewee, a Great Crested Flycatcher, and a Least Tern.  Not too shabby given how limited my field of vision was.

I was compelled for much of this outing to keep my eyes focused on the ground (lifting them only when someone else spotted a bird), but, as an instance of how contingent life is, at one point I spied a small, off-white object pressed into the trail.  It looked for all the world like a piece of heavy duty electrical cable, but once I pried it free, I realized with delight that it was more likely to be a fragment of a clay pipe stem.

That’s what it was; I have since given it to the group that manages this preserve.

This serendipitous find opened a door to the fascinating world of the archaeological study of English colonial clay pipes, particularly stem fragments.  Lance’s Tizer ring pull is analogous, in a very small way, to clay pipe stem fragments.  Were archaeologists on a dig in that same Essex field as depicted in the Detectorists some 200 years hence to come upon several examples of that same ring pull, they might well date the layer of their excavation which give them up to 1983, give or take.  So it is with pipe stem fragments; they have become one important means of dating archaeological sites of colonial America.  And of course their range is much broader than the decade, or decade and a half, during which pop tops were torn from soda cans and discarded like so many cigarette butts.

Though pipe bowls are also used in the dating process, pipe stem fragments are apparently go-to artifacts partly because these pieces are often found in staggering numbers (stem fragments were so plentiful in colonial times they were sometimes used as ballast in ships; one path in Williamsburg was “paved” with some 12,000 stem fragments) and complete bowls are relatively rare.

It was the analysis of the diameters of the bore holes in pipe stem fragments by archaeologist Jean Carl Harrington that apparently launched the widespread use of such fragments in the dating process.  He reported,
In working with the Jamestown pipe collection I had observed that the early pipes have relatively large holes through the stems, while the holes in later specimens are much smaller.  If this represented a definite and consistent trend, then it might possibly be useful as a dating criterion.  (J.C. Harrington, Dating Stem Fragments of Seventeenth and Eighteenth Century Clay Tobacco Pipes, Quarterly Bulletin of the Archeological Society of Virginia, 1954.)
His work showed that there was in fact a “definite and consistent” trend in how the bore hole diameters clustered in five broad time ranges.  Within different ranges, different hole sizes accounted for the majority of stem fragments.  The key element in his article was a graph (below) that showed the clustering across each time period, a graph that could easily be used in the dating process if one had the average bore hole sizes for a sample of stem fragments from an undated site.  The Y-axis for each time period measures the percentage of the stem fragments in that period featuring a specific bore hole measurement.  The X-axis presents the range of bore hole measurements in increments of 64ths of an inch.

The graph can be read as follows:  in the 1650 – 1680 time range (second from the bottom), Harrington found that 57% of the holes were 7/64ths of an inch wide, another 25% were 8/64ths of an inch wide, and the remaining 18% were 6/64ths of an inch wide.  Were the average bore hole size of a cluster of fragments from an undated site to fall somewhere within these sizes, it was a good bet the site was probably from the 1650 – 1680 time period.

One of the most fascinating aspects of Harrington’s work is its unit of measurement – 64ths of an inch.  It’s such a curious standard but one easily explained by the tool that he used to measure the bore hole diameters of the fragments he analyzed – the metal bits for drills.

Pictured above is one of my sets of drill bits.  Note that they are measured in 64ths of an inch (or some factor of 64 – e.g., 1/16ths is 4/64ths).  Harrington, I have to believe, decided early on that calipers wouldn’t do the trick to measure the hole diameters, nor would trying to rest a ruler across the uneven surface of either end of a fragment.  Wondering what to use, he cast his eyes about his lab (workshop?) and spotted his drill bits.  As he wrote,
In making use of this dating device [his graph], the first requirement is a 39-cent set of drills; the second is common sense.  (Dating Stem Fragments.)
The cost of drill bits has risen markedly since the early 1950s.  Common sense?  In short supply today in many areas.  Harrington cautions against using his graph for a single specimen unless one is using common sense and making only rough estimates about the age of the specimen.  Certainly, it would be foolhardy to use a single specimen to date a site.

So what does Harrington’s graph say about the age of the pipe stem I found?  Well, I cannot duplicate his work precisely with that stem fragment because I give it to the preserve administrators before I’d learned enough about his dating process to turn to my drill bits and see which one fit.  So I worked from the crude measurements I had taken.  The 3.3 mm hole diameter shown in the picture above is slightly less than 0.13 inches.  I make the not unreasonable leap that a drill bit of 8/64ths inch size (or 1/8ths inch) would have fit nicely into that bore hole but not any other drill bit sizes (the rest too big or too little).  The numbers bear me out:  3.3 mm is slightly less than 0.13 inches; 8/64ths inch is 0.125 inches.

Given that, I turned to Harrington’s graph and saw that the time period in which the majority (59%) of bore holes are 8/64ths inch in diameter is 1620 – 1650.  In the next youngest time period (1650 – 1680), only 25% are 8/64ths of an inch.  What can I say with confidence?  Only that this pipe stem probably dates from the 1600s, and possibly from the first half of that century.  (These formulas regarding bore hole diameters apply principally to English clay pipes, not Dutch pipes, whose bore hole diameters are more variable.  Distinguishing between these white clay pipes isn’t always easy, though Dutch pipes are reportedly much softer than English pipes – my fragment is quite hard.)  The possible 17th century dates for this fragment square quite nicely with what I know about the history of the particular preserve where I found the stem.

Harrington’s article presented a very useful piece of analysis with a practical application which, in time, apparently prompted archaeologists working colonial sites where pipe stem fragments were present to do field work or lab work armed with cheap sets of drill bits.

There has been a great more work done by archaeologists trying to render data on the hole diameters in pipe stem fragments into a more mathematically precise dating tool.  Archaeologist Lauren K. McMillan turned her masters thesis into a succinct and accessible article that nicely summarizes the work done to date.  An Evaluation of Tobacco Pipe Stem Dating Formulas (McMillan, Northeast Historical Archaeology2016) offers strong evidence for her choice of the best of the analytical methods using these hole diameters to date sites.  She argues in favor of the formula derived by Robert F. Heighton and Kathleen A. Deagan (A New Formula for Dating Kaolin Clay Pipestems, The Conference on Historic Site Archaeology Papers 1971, Volume 6, Part 1, Stanley South, Editor, June, 1972).

Based on their analysis of English pipe stem fragments from an array of sites, the Heighton/Deagan formula reads as follows:


In this formula, Y is the bore hole measurement (the mean of the hole diameters in fragments from a site).  Reflecting the measurement standard set by Harrington, that bore hole measurement is in 64ths of inch.

So, assuming my fragment’s bore hole would be 8/64ths of an inch, the Heighton/Deagan formula gives a date of 1658, a date much too precise to be assigned to this single fragment, but certainly within the range that the Harrington graph suggested.

Later, I came upon a couple of clay pipe bowls in an antique store on the North Fork which I purchased despite their very vague provenience:  “Oh, they were found somewhere around here.”  One of these is pictured below with an image of its bore hole.  A 4/64ths inch drill bit fits perfectly in that hole suggesting this bowl dates from the latter half of the 18th century (using Harrington’s graph) or about 1782 (using Heighton/Deagan).

All of this begs a fundamental question:  Why did the bore holes trend smaller as time went on?  The commonly proffered answer is that stems grew longer and thinner, and so the bore holes had to become smaller.  I don’t find that altogether satisfying.  Why were stems longer?  Other aspects of the pipes changed over time, particularly the size of the bowls which grew larger as tobacco became cheaper.  Might there be something going on with trying to keep the amount of smoke inhaled with each breath roughly constant over time?  A puzzlement.

I turn back to the Detectorists.  During Season 2, Andy, who has completed an archaeological certificate, interviews for a job on a dig that will occur in Botswana (Episode 4).  Seated in a hall outside the room where the interviews are being conducted he notes that some of the other candidates have better beards than his and dirty finger nails to boot.  He momentarily leaves the building to find some dirt to rub into his hands.  While crouched down and rooting in a flower bed he comes upon some objects which he pockets.  At that moment, one of the leaders of the Botswana dig comes by and spots him.  Andy looks up sheepishly, though he has no idea who the man is.  Needless to say he discovers the man’s identity during the interview which is a disaster.  Later, while Andy is standing outside bemoaning the interview experience, the dig leader passes.

Andy:  Sorry, I just wanted to say, I wasn’t picking up cigarette butts.

Dr. Tendai:  Excuse me?

Andy:  Earlier when you saw me, I wasn’t picking up cigarette butts.

Dr. Tendai:  Oh.

Andy:  Clay pipes.

Dr. Tendai:  Pardon?

Andy:  I . . . I saw some bits of clay pipe in the flower bed. . . .  I . . . .

Andy hands the fragments to Dr. Tendai.

Dr. Tendai:  What are they?

Andy:  Broken bits of pipe, you know, that people used to . . . smoke.

Dr. Tendai:  How old are they?

Andy:  Uh . . . These ones are Victorian.  But that one’s early 18th, maybe late 17th century.

Dr. Tendai:  Hmmm.  How can you tell?

Andy:  The older ones are thicker and they had a much smaller bulb because tobacco was so expensive.

Dr. Tendai:  Okay.  And you found these just here?

Andy:  Yeah, just . . . .  Yeah.

Dr. Tendai:  Can I keep these?

Andy:  Yeah.

Ah, the myriad contingencies of life.  I wasn’t picking up cigarette butts, I was bird watching.

Nature Blog Network