Message #170:
From: AzTeC SW Archaeology SIG
To:   "'Matthias Giessler'" 
Subject: VARA -- A Spanish Unit of Measure in the American Southwest
Date: Sun, 26 May 1996 16:18:23 -0700 (MST)
Mime-Version: 1.0

Smoke Pfeiffer asked a question on the SASIG a while back, and now, Rolf
Sinclair and Clive Ruggles have come through with an interesting answer and
some additional information for consideration!  Any other takers...??

Original SASIG Question --

From: Smoke Pfeiffer:

VARA  --  Spanish unit of measurement used in American southwest until ca.
1846 and offical in Mexico until the 1890s, equaling 83.5cm or 32 5/8ths
inches. It was an oak stick divided into 4 sections of 21cm called a
handsbreadth, by brass studs. These were again divided into two 10.5cm
sections and the outer ones into 5.2cm sections called the two
fingers'breadth.  (Boyd, E., 1954, The Vara, A Unit of Measurement. El
Palacio 61(2):46-47). Does anyone know anything more about this???  Please
E-mail me with additional details.  Thanks, Smoke Pfeiffer

Answer -- Spanish Unit of Measurement in the American Southwest

From: Rolf Sinclair, NSF Physics Division 

I had meant to reply to Smoke's question earlier, and am doing so now as
part of spring cleanup in my office. What I quote below is open to question,
so form your own conclusion. Alexander Thom surveyed hundreds of the stone
circles and similar constructions in Great Britain and Brittany (these date
from a few thousand BC). From his careful surveys he concluded that these
constructions were laid out using a common unit of measure -- the
"megalithic yard" = MY = 2.720 +/- 0.003 feet. See his "Megalithic Lunar
Observatories", 1971, p. 9. In "Megalithic Sites in Britain" (1967), Ch. 5
he derived this in some detail. He refers briefly there to the history of
the vara in Spain (= verge in France),  and speculates that its origin is
this megalithic unit of length. This does push the origin of the vara back 
quite a way! Trouble is that Thom's work has been criticized. Clive Ruggles 
(U. Leicester) has re-done a lot of Thom's surveys. I asked Clive about the 
MY, and got the following reply. I don't know how far you want to push this, 
but I thought you might find this interesting.
Rolf Sinclair

Memo to/from Clive Ruggles:
Date: Thu, 1 Feb 96 08:19:45 GMT
To: (Rolf Sinclair/NSF Physics Division)
From: Clive Ruggles
Subject: Re: The "Megalithic Yard"

Hi Clive --
In Thom's "Megalithic Sites in Britain" he devotes Ch. 5 to the megalithic
unit of length, and argues for a "megalithic yard" = 2.72 +/- 0.003 ft. He
also wrote on this subject in statistical journals, and he sent me a couple
of reprints of such papers in the 60's/70's, but I can't lay my hand on them
at the moment. What is the present thinking on this subject? Has anyone
looked anew at this idea, either using Thom's surveys or later re-surveys?
Have you found any evidence in your own work for a unit of length of this
size (or any other size)? Plz advise. Rolf

Hi Rolf
The original paper by Thom on this was in JRSS, A118, 275-95. Statistical
reassessments of Thom's data both from classical (Kendall, PTRS, A276,
231-66, 1974) and Bayesian (Freeman, JRSS, A139, 20-55, 1976) viewpoints
reached the conclusion that the evidence in favour of the MY was at best
marginal, and that even if it does exist the uncertainty in our knowledge of
its value is of the order of centimetres, far greater than the 1mm precision
claimed by Thom. In other words, the evidence presented by Thom could be
adequately explained by, say, monuments being set out by pacing, with the
'unit'  reflecting an average length of pace. But not everyone agrees (e.g.
Davis, Glasgow Arch J, 10, 7-11, 1983). The statisticians only accepted
evidence from circular stone rings, thus severely reducing Thom's own (1967)
data set. The reason was that Thom linked his arguments about geometrical
shapes to the proposed unit of measure. Thus geometrical constructions were
fitted to sites by assuming an MY value, while data for the analysis seeking
to establish the reality of the MY included the lengths of constructors in
these same geometrical models. From a statistical point of view mensuration
and geometrical design are formally independent hypotheses, requiring
separate testing. Any help? Clive
* Clive Ruggles                                                             *
* School of Archaeological Studies, Leicester University, Leicester LE1 7RH
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* TLT Support Network: Leicester Centre                                     *
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