Books, Prehistory, Historical Views of Devonshire

Its form, on a superficial view, has been commonly considered as that of an irregular Trapezium, two of whose 4 sides are partly curv'd, another wholly so, and only one appears to be in a right line; but even this is not strictly so. This, some would have to be the shape in which it happen'd to be form'd in its quarry, with little or no alteration by the hand of a workman; but on a nicer examination it appears to form an hexagonal figure, three of whole sides are straight lines (saving a very small curvature at the extremity of one of them), and the other three, curves; and these described with the utmost regularity and exactness: Wherefore, tho' we may sometimes occasionally call it a Trapezium, it must not be so strictly understood as having that kind of figure to which geometers confine that name. The upper part of this trapezium or table-stone, is as usual in other Cromlechs, bulging and gibbous, or, as the countrypeople express it, saddle-backed; but its under surface, tho' not smoothly polish'd, is, or originally was, almost every-where a plane, and free from irregular knobs or bunches. This plane makes an angle with the plane of the horizon of about 3 degrees and 55 minutes: For it is to be observ'd, that its three supporters are of unequal heights, and consequently the plane they support cannot be horizontal, but inclines a little downward, as is the case in most other Cromlechs we have any account of, at least of those in the British isles that have been with any degree of precision described. Among other seeming irregularities, the inequality of the heights of the supporters, which occasions this inclination or declivity, and gives ours a dip towards the south-west, was not accidental, but designedly chosen as most expedient to answer the purposes for which the Cromlech was erected. The thickness of the table-stone is different in different parts of it. In the part over the middle supporter, which most bulges or swells upward, it has been found, on a late careful mensuration of it, to be not less than 3 feet and seven inches: From thence this thickness diminishes more or less every way towards the sides of the trapezoid respestively, where the thicknesses also vary. For, towards the north-west, it is from 20 inches to a feet thick: the arch'd part at the north-east is rounded off to a blunt edge, both above and below: the south-east side (where its thickness would otherwise be 17 inches) is under-cut inward, so as to form a reclining plane 22 inches in the slope back, or 14 inches horizontally; and this reclining continues for 7 feet and 7 inches in length, to that point where the curvilinear boundary begins. Between this point and that part which projects over the eastern edge of the lower prop, there has been an excavation of its upper surface, and a seeming abruption of some part of it whether originally so design'd, or the effect of violence since, we may hereafter have occasion to enquire. On the whole, the average thickness of this covering stone may be estimated at one foot and 9 inches, or near half the greatest thickness of its bulging part. But more of this, and of the nature and length of the curves which form three on its sides, when we come to specify its dimensions and properties more minutely. This may suffice at present, with regard to its general dimensions and form; of which latter however, the View of it prefix'd to this tract will give those who have not seen it a more perfect idea than any verbal description. But as, among other dimensions, having repeatedly survey'd it, in order to have a perfect plan, I took care (by girthing and otherwise) to have sufficient to determine its solidity also; and from thence, and the known specific gravity of the moor stone of which it wholly consists, to be enabled to ellimate its weight; it may be more proper here to give the result of those measures, than to interrupt our intended enquiries into its geometrical construction by introducing it there. The areas of the several parts into which the plane of its under surface was to be divided, as the different thicknesses required, in order to obtain their respective solidities, being requisite to be first ascertain'd; I thence found the sum of those areas, or the whole superficial area of this undermost surface or plain part of the table-stone, to be 125 square feet; being not quite half of a square perch, tho' very little short as wanting not a 12th part of it. And this is the quantity of ground it covers, or rather overshadows, at about 6 feet and 3 or four inches, on an average, in height from the surface of the ground: which height is meant of the under part of the stone only; that of its upper (as may be gathered from the above dimensions) being from 6 to at least 9 feet and half. The different thicknesses being carefully distinguish'd as above, with the superficial areas under each, and the bulging upwards allowd for; I thence found the whole solidity of the said stone (disregarding a very small fraction of a foot) to be 216 cubic feet very nearly. Now a cubic foot of water weighing 62 lb ½ a'voirdupois, and the specific gravity of moorstone being found, by the experiments of Mr. Labelye the Westminster Bridge Engineer, to be to that of water, as 2.656 to 1; from the above solidity we have 216 x 62,5 x 2.656 = 35856lb. avoirdupois, for the neat weight of the covering stone of this Cromlech: that is, in gross weight (reckoning as usual 112lb. to the hundred, and 20 such hundreds to make a tun), sixteen tun, with an addition of 16 pounds avoirdupois.

The use of the Cromlech has been a subject of much conjecture. An ingenious writer says, that the Cromlech is the Bith he ram of the Canaanites and that its name declares it to have been a temple dedicated to there god, the heavens, under the attribute of the projector, eye mover of thin projetected. Mr. Chapple was of opinion, that the Cromlech was designed for the apparatus of an astrononiical observaton. So numerous were the scientific properties which he ascribed to the Drewsteignton Cromlech, that he could have written (as he often said) in describing them. The first thing he mentioned was a most exact meridian line, made by the coincidence of the three supporters — that is, the outside edges of two, and the inside edge of the third, are so truly fixed on the meridian as could possibly be done by the most accurate astronomer. The next was the latitude of the place, which was shewn by some part of the Cromlech, even to the nearest minute; as were the sun's greatest meridian altitude in summer, the least ia winter, and consequently the obliquity of the ecliptic — which last article afforded a most curious circumstance; for, by allowing the known diminution of the obliquity, he found that upwards cf two thousand two hundred years had elapsed since the Cromlech was erected. After describing these, and many other astronomical properties, he said he had lastly discovered, that the cover-stone was inscribable in an ellipsis. And that the Cromlech served also for gnomonical purposes, he had the most positive proof. For by its construction, he found that there was a certain point under the Cromlech, whence reflections should be cast; and, by removing the earth from that spot, he discovered a curious little triangular stone, which must have been placed there for that purpose. All this is wonderful indeed! But though I have the highest opinion of Mr. Chapple's diligence and integrity, yet I am apt to believe that his curious hypothesis, which might first be suggested by some fortuitous polition of the stones, will not bear the test of cool and impartial examination. Were there any regular planes cut on the surface of these stones, we might suppose them designed to point out difierent phenomena of the sun and planets: but, as there is no mark of a tool on any of them (which, indeed, would profane them in the opinion of a Druid) I would as soon believe that the earth was formed by a concourse of atoms, as that four rude and shapeless stones, to all appearance selected only for their magnitude, should exhibit an exact correspondence with every circle in the heavens.