thom's megalithic yard and traditional measurements

Thom's Megalithic Yard and Traditional MeasurementsAuthor(s): Ronald HicksSource: Irish Archaeological Research Forum, Vol. 4, No. 1 (1977), pp. 1-7Published by: Wordwell Ltd.Stable URL: http://www.jstor.org/stable/20495250 .

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IRISH ARCHAEOLOGICAL RESEARCH FORUM IV (1), 1977

THOM'S MEGALITHIC YARD AND TRADITIONAL MEASUREMENTS

Ronald Hicks

In a series of writings over the past two decades (see especially 1955; 1962; 1967, 34-55),

Alexander Thorn has argued for the use in ancient times of units of measurement that he has

termed the megalithic fathom (5.44 ft or 65.28 in.) and megalithic yard (2.72 ft or 32.64 in.).

He has also suggested the existence of a rod (Thorn & Thorn 1972, 13), a half yard (1962, 251),

and a megalithic inch (0.816 standard inch or one forteith of a megalithic yard ?

1968, 1969).

His conclusion concerning these that "there must have been a headquarters from which standard

rods were sent out" (1967, 43).

In support of his argument for a megalithic yard, Thorn (1967, 36-39) has provided a table of

diameters for 145 stone circles and rings, indicating for each the multiple of yards and fathoms

involved as well as the residuals (i.e., the amounts by which each diameter differs from an exact

multiple of the proposed megalithic units). As has been pointed out by Hammerton (1971), the

actual range of values for the megalithic units is considerable when these residuals are taken into

account, raising some doubt concerning the existence of a standardized unit. Figure 1

summarizes the lengths of these "nonstandard'. megalithic yards, calculated on the basis of the

site diameters and yard multiples supplied on Thorn's table1. The range is from 2.54 ft to

3.00 ft and in only two cases do these yards exactly match Thorn's standard value of 2.720?

0.003 ft. The corresponding range for the fathom is 5.08 ft to 6.00 ft. In a complex statistical

re-analysis of Thorn's data, D. G. Kendal (1974, 249) has concluded that if data from both circles

and "eggs" are used, the existence of the standard fathom is indeed supported by the evidence,

but only just barely; it is neither proven nor rejected at the 7% level if only the 112 accurately

measured circles are used as a data base. He goes on to point out that the evidence for a standard

quanta is shakier in the English and Welsh sites than in those of Scotland. The existence of the

megalithic rod has also been questioned, in the pages of this journal by Patrick & Butler

(1974,32-34).

Despite the problems with the theoretical standard megalithic yard or fathom, the data

nonetheless strongly suggest the existence of some commonly used, although perhaps non

standardized, unit in megalithic construction. What other alternatives can be offered?

Dr. Hammerton, in the note referred to earlier, proposed the use of the height of the person in

charge of construction or of some local dignitary as a standard, which for the postulated fathom

would require an average stature among those used of 65.3 inches, somewhat less than that of

modern males. Another alternative, that the measurements were done by pacing, has been

offered by H.L. Porteous (1973; Hodson, ed., 1974, 270), Kendal (1974, 258) has also admitted

the feasibility of pacing, as has Thorn himself (1974, 149-150) in the case of the earlier circles,

although he feels it inconveivable that such constructions as Avebury, the Le Menee alignments, or the Ring of Brodgar could have been laid out in that way. It must be admitted that the use

of pacing, the height of an individual, or even yardstick would involve a number of practical difficulties in the laying out of complex ovals or ellipses or even of simple circles. By far the

earliest method would have been to use a line fastened at the centre ? in effect a giant compass.

Rope or cord does tend to stretch, but this is likely to have been less of a problem than pacing off

a straight line in many different directions from a common centre and far less than using a

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yardstick for that purpose. Of course a combination of these methods may have been used,

e.g., measuring off a desired length of line against a yardstick or even against a local dignitary

(who will doubtless have been honored to stretch him ? or herself out neatly on a nearby slab

for the purpose!).

In all these discussions what seem to have been overlooked are traditional nonstandardized

measuring methods other than pacing. These are usuaily based on various bodily proportions,

many of which have formed the basis for later standardized units (see, for example, the

discussion in Hallock & Wade 1906). In some regions (such as the Indiana countryside where I

grew up) they are still used for measuring line or cloth when a yardstick is not available. Very

similar sets of body-based measurements have been found by metrologists, classical arch

aeologists, and ethnographers to be used not only in Europe and the Mediterranean region but

also throughout much of the world, including Melanesia and among the American Indians. This

suggests either their very great antiquity or their obviousness. In either case it seems highly

likely that similar measurements were used in prehistoric Britain.

The traditional measures include, among others, the inch (a phalange of one of the digits),

hand (still used for horses), foot (hence the name), span, cubit, yard, and fathom. The last

three of these are most relevant for this discussion. The cubit (length of the forearm) is

equal to approximately half the yard (distance from the nose or midline of the body to the

thumb or palm) which in turn equals approximately half a fathom (distance between extended

hands); for example, repeated measurements of myself provided a cubit equal to 0.25 fathom

and a yard equal to 0.53 fathom. Tradition claims that the length of the standard English yard

was established by Henry I in exactly this way (with the king himself as standard).

Whether or not a standardized megalithic yard existed (which I doubt), it seems to me nearly

certain that the measurements used in the construction of the stone circles were based ultimately on some variant of this system. As a test of this hypothesis, I recently conducted a simple

experiment using a sample of 91 students (64 male, 27 female), from whom were obtained

statures plus measurements of the natural yard and fathom2. Even before the experiment was

begun it was clear that a wide range of variation could be expected for any given height not only

because of variations in bodily proportions but also because of individual variations in performing

the measurements. In addition, available anthropom?trie data suggested that we could expect

the measurements to reflect a noticeable difference between the male and female volunteers

(Olivier 1969, 25-26), with the males having arms slightly longer in proportion to their statures

than the females. The results amply bore out these expectations. It is probable that slight differences also exist between different geographical populations (Olivier 1969, 23) but the

sample (composed primarily of students of Afro-American, Eastern European Jewish, and mixed

Western European ancestry) was much too small for this to be evident. One further caution

concerning my data should also be mentioned. Despite urgings that they carry out the

measurements in a relaxed, natural way, there was an observable tendency for the volunteers to

see how far they could stretch for the yard (though much less so for the fathom). This almost

certainly caused the average for this measurement to be higher than it should have been, probably

by 1.5 inches or more.

Figure 2 presents the results of the experiment, showing for each height (by 1/2-inch intervals)

the range of values obtained. A summary of the resulting averages is presented in Table 13, where it can be seen that the average "yard" for females was slightly below Thorn's figure and

that for males somewhat above, although both are within the range shown by Figure 1. The

2



o ?o o

Length of "Yard" (ft)

Figure 1. "Megalithic yard" lengths based on the site diameters and

yard multiples supplied in Thorn 1967: 36 ? 39.

YARDS FATHOMS

Statur e ( inch? & )

Figure 2. Lengths of traditional yards and fathoms plotted against

stature for sample of 27 females (top) and 64 males (bottom).

3



average fathom for males is within an inch of Thorn's figure. Using the average proportions of

yard to stature and fathom to stature calculated from these data, it was possible to calculate

the necessary average statures required for Thorn's megalithic yard and fathom to have been

derived in this way (Table 2). The sizable difference between the projected statures for the

yard and for the fathom may be traceable at least partly to the tendency to stretch mentioned

in the preceding paragraph. I suspect a more accurate figure for the yard would be on the order

of 67.35 inches (5.61 ft) only slightly less than the required stature for females. This would

provide an average required stature (col. 3) for males of 68.21 inches (5.68 ft).

How do these results compare with what it known of the statures of prehistoric and historic

peoples? Hammerton's suggestion that height provided the standard for measurement would,

as noted, require an average stature of 65.28 inches as well as the validity of the usually accepted

view that average statures have gradually increased through time to the present higher figure.

However, this second requirement has been challenged by Huber (1968), who on the basis of

available archaeological samples argues that the mean stature of males in the past (at least in

Europe) did not differ substantially from today's average of 68.70 inches recorded for U.S.

white males4. In his view, studies seeming to show an increase over the past century, based

primarily on measurements of military inductees and students, reflect instead a higher

proportion of immature individuals in the earlier samples (i.e. a decrease over the past century

in the age at which skeletal maturity is reached, suggested by other data as well). To support

this view he offers estimated mean maximum statures for nine skeletal populations, as shown

in Table 3. To these perhaps we can add the small Iron Age sample from Dunbar reported by

Brothwell S Powers (1964/66?8) males, mean stature 66.59 inches or 5.55 ft). The average

stature indicated by these ten samples from northwestern Europe is 68.26 inches (5.69 ft).

Unfortunately, comparable data is not available for females; however, on the basis of my

small sample it appears that for females to have been exclusively responsible for a traditional

yard equivalent to Thorn's megalithic yard they would have had to be unusually tall. This

does not rule out the possibility, on the other hand, that the observed measurements were

the result of a mixture of male and female sources. The figure of 68.26 inches (68.45 inches

if the Dunbar sample is omitted) compares quite well with that needed to produce the observed

measurements provided by Thorn.

While my sample was too small for really good results and there were various other problems, as noted, I believe there can be little doubt that the megalithic units, standardized or not, could

indeed have been based on the same bodily measurements as the traditional units. This system seems more practical than Dr. Hammerton's suggestions; while it has the advantage over pacing of allowing the simple measurement of lengths of line. The half yard proposed by Thorn could

be the cubit, and this system would produce a distribution of lengths roughtly comparable to

that actually found in Thorn's data. Given these points and the knowledge that this method

of measurement is widely attested both historically and ethnographically, it seems to me to

provide altogether the most satisfactory explanation for the observed regularity in the diameters

of the megalithic rings.

4



Notes

1A table showing the lengths, to three decimal places, on which Figure 1 is based will be

provided on request. It is omitted here as being too space consuming and expensive to set into

type.

2 I would like to acknowledge with thanks the assistance of David Armstrong, Mary Hediger,

and the students in their and my own introductory anthropology classes at the University of

Pennsylvania, Community of College of Philadelphia, and Spring Garden College who volunteered

to participate.

3The actual data will be provided to any interested parties on request. It is omitted here as

being nonessential to the argument (since displayed in Figure 2) as well as for the reasons in

note 1, above.

4 It should perhaps be noted that college males, as in my sample, tend to be taller than the

average for any given population (Huber 1968:95).

Table 1

Summary of Data Averages

Male

Female

All

Stature

69.91 (5.83)

65.12 (5.43)

68.49(5.71)

Averages (In./ft) Yard

35.38 (2.95)

31.52(2.63)

34.24 (2.85)

Fathom

66.09(5.51)

61.63(5.14)

64.65 (5.39)

Ratios

Yard/Stature Fathom/Stature

0.506

0.484

0.500

0.946

0.935

0.943

Table 2

Average Statures Required for Thorn's Megalithic Units

(in inches)

Male

Female

All

Yard

64.49

67.43

65.29

Fathom

69.06

69.55

69.15

Average

66.70

68.47

67.17

5



Table 3

Mean Maximum Statures for Nine Skeletal Populations

(after Huber 1968:93)

Mean

Population Stature (in.)

Late Neolithic Danes 69.92

Bajuvar, row-graves 69.09

Th?ringer, row-graves 68.66

Saxons, row-graves 68.39

Alemanns, row-graves 68.19

Anglo-Saxons 68.19

Medieval Swedes 68.15

Medieval Norwegians 67.80

Medieval English Midlands 67.64

Brothwell, D. and

Powers, R. (1964/66)

Hallock, and

Wade, HT. (1906)

Hammerton, M. (1971)

Hodson, F.R., ed. (2974)

Huber, M. (1968)

Kendall, D.G. (1974)

Oliver (1969)

Patrick, J., &

C.J.Butler (1974)

Bibliography

'The Iron Age people of Dunbar, Part II." Proc. Soc.

Antiq. Scotland, 98, 1964-1966, 184-198.

The evolution of weights and measures and the metric

system, New York (Macmillan), 1906.

"The Megalithic fathom: a suggestion" Antiquity 45,

1971,302.

"The place of astronomy in the ancient world".

Phil. Trans. Roy. Soc. London. A, 276, 1974, 1-276.

"The problem of stature increase: looking from the

past to the present" In D. R. Brothwell, ed., The skeletal

biology of earlier human populations, Oxford

(Pergamon Press), 1968,67-102.

"Hunting quanta" In Hodson, Ed., 1974, 231-266.

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Charles C Thomas (French edition 1960).

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Porteous, L. (1973)

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(1962)

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