THE TREGASEAL CIRCLES (LAT. 50° 8′ 25″ N., LONG. 5° 39′ 25″ W.)
There are two circles situated on Truthwall Common near to Tregaseal and
not far from St. Just; the one is nearly to the east of the other, and
there are outstanding stones, including four holed stones, and several
barrows. The eastern temple has a diameter of 69 feet, and includes, at
the present time, nine erect and four prostrate stones; the original
structure seems to have contained twenty-eight stones according to
Lukis.
My wife and I visited the region in January, 1906, but previously to our
going Mr. Horton Bolitho, accompanied by Mr. Thomas, whose knowledge of
the local antiquities is very great, had explored the region and taught
us what to observe.
The chief interest appears to lie on the N.E. quadrant, where, in
addition to a famous longstone on a hill about a mile away, the nest of
holed stones and several of the barrows are located. Carn Kenidjack, a
famous landmark, lies to the north.
Of the two circles, I confined my attention almost exclusively to the
eastern one, as the other is in a fragmentary condition, though it is
still traceable. It is hidden almost entirely from the eastern circle by
a modern hedge.
Mr. Horton Bolitho, who accompanied us in January, has again visited the
spot, with Mr. Thomas, for the purpose of further exploration, and
determining the angular height of the sky-line along the different
alignments, which I have plotted from the 6-inch and 25-inch maps. My
readers will therefore see that my part of the work has been a small
one, and that they are chiefly indebted to those I have named.
No theodolite survey has as yet been made for determining the azimuths
and the height of the hills. The following approximate azimuths have
been determined by myself from a 25-inch map, and the elevations by Mr.
Horton Bolitho by means of a miner’s dial.
Alignments. Azimuth. Elevation.
1. Apex of Carn N. 12° 8′E. 4′ 0′
2. Barrow 800′ distant N. 20 8 E. 3 50
3. Two barrows 900′ distant N. 50 8 E. 1 50
4. Holed stones N. 53 20 E. 1 15
5. Longstone N. 66 38 E. 2 10
6. Stone N. 76 13 E.
The carn referred to in the above table is Carn Kenidjack, called “the
hooting cairn.” The rocks on the summit, in which there is a remarkable
depression, are still by local superstition supposed to emit evil sounds
by night.
[Illustration: _Photo. by Lady Lockyer._
FIG. 54.--The Eastern Circle at Tregaseal.]
Of the sight-lines studied so far, those to and from the Longstone and
the holed stones seem the most important. The Longstone,[117] 1¹⁄₂ miles
to the N.E., is a monolith 10 feet high on the western side of a hill;
it is visible from the circle though furze has grown round and partly
hidden it.
The meanings of the various alignments seem to be as follows:--
Decl. N. Star. Date.
1. Apex of Carn 42° 33′ 0″ Arcturus 2330 B.C.
2. Barrow 800′ distant 40 29 0 „ 1970 „
3. Two barrows 900′ distant 25 20 21 ? Solstitial
4. Holed stones 23 2 20 ? „
5. Longstone 16 2 0 May sun
6. Stone 9 15 0 Pleiades 1270 B.C.
Regarding the possible solstitial alignments, the declinations obtained
may be neglected until the azimuths and angular heights of the hills
have been determined with a good theodolite. A change of -10′ in the
angular elevation, and hence about that in the resulting declination,
would bring the date given by the barrows to about 2000 B.C.
The position of the Longstone is well worthy of attention. Several very
fine monuments which mark the surrounding horizon are visible from it in
azimuths with which other monuments have made us familiar. They are as
follows:--
Alignment. Az. Hills.
Longstone to Mên-an-tol N. 50° 30′ E. 0° 34′
„ Nine Maidens (Boskednan) N. 54 0 E. 1 0
„ W. Lanyon Quoit N. 67 0 E. 0 0
„ Lanyon Quoit N. 72 45 E. 0 0
These values, of which the angular heights of the hills were determined
approximately from the contours on the 1-inch Ordnance map, lead us to
the following declinations:--
Alignment. Decl. Star. Date.
Longstone to Mên-an-tol 24° 7′ N. Solstitial sun.
„ Nine Maidens 22 37 N. „
(Boskednan)
„ W. Lanyon Quoit 14 3 N. May sun.
„ Lanyon Quoit 10 30 N. Pleiades 1030 B.C.
[Illustration: FIG. 55.--Photograph of Ordnance Map, showing
sight-lines.]
The May-sun alignment, it may be noted, differs from that from the
circle. The heights of hills when determined may give us the same solar
declination; that now used gives the declination for April 28 and August
15 in our present calendar.
Regarding the alignment on Lanyon Quoit, it need only be pointed out
that the Pleiades date obtained is some 200 years after the date
obtained for the analagous alignment from the circle, showing that if
these two monuments--the Tregaseal circle and the Longstone--have any
relationship, the removal to the high plain, now known as Woon Gumpus
and Boswen Commons, was an afterthought improvement.
I next come to the holed stones, not only the nest of them not far from
the circle, but the famous Mên-an-tol itself.
I had heard before going to Tregaseal that the four holed stones shown
on the Ordnance map had been knocked down and set up again (not
necessarily in their old places) two or three times. Mr. Horton Bolitho
and Mr. Thomas, however, in their examination were convinced that the
largest of them has never been moved. They also express the belief that
the others are not more than a foot or so from their original positions,
and that this change is only due to their re-erection by Mr. Cornish
after they had fallen down. So far I have heard nothing of the direction
of the hole in the stone which retains its original position.
Another interesting matter is that the explorers in question were able
to trace an ancient stone alignment from the circle to the holed
stones.
I have long held that these holed stones were arrangements for
determining an alignment. The famous Odin stone at Stenness, long since
disappeared, was, if we may trust the very definite statements made
about its position, used to observe the Barnstone in one direction and
the chief circle in the other.
[Illustration: FIG. 56.--Plan of the Mên-an-tol from Lukis, showing that
it was an apparatus for observing the sunrise in May and August in one
direction and the sunset in February and November in the other. Sun’s
declination, 16° N. or S.]
The azimuths suggest that theodolite measures may show that the
Tregaseal stones might have been used in the same way; they, the
Longstone and Lanyon Quoit, are in nearly the same straight line, the
alignment, holed stones to Longstone and Lanyon Quoit, being N. 67° E.,
so that the May sunrise may have been noted in this way.
[Illustration: _Photo. by Lady Lockyer._
FIG. 57.--The Mên-an-tol.]
Several other monuments, _e.g._, Chûn Castle and Cromlech, are to be
found in the immediate neighbourhood of the Tregaseal circle and the
Longstone, but these will have to await further investigation as to
their character and antiquity before any conclusions concerning their
astronomical use can be deduced.
[Illustration: FIG. 58.--The Mên-an-tol. Front view and section, from
Lukis.
~Front view: D. LOOKING S.W., SCALE 1 INCH TO 1 FOOT.~
~Section: SECTION OF D.~]
Not only do we find in this neighbourhood the nest of holed stones to
which I have referred, but the Mên-an-tol, the most famous of them all,
in England at all events. This, then, is the place to say a few words
about them. I have before stated my opinion that these stones, instead
of being used as slaughter stones or posts at which to tie up the victim
before sacrifice, or in any other similar employment, were really
sighting stones to enable an alignment to be easily picked up. As such
these were, of course, treated as sacred, and hence the folk-lore
connected with them. This folk-lore seems to be most complete in the
case of the famous stone of Odin at Stenness, so I condense Mr. Spence’s
account of it.
Children brought to the stone at Beltaine and Midsummer, after being
carried sunwise round the holy well were passed through the hole as a
protection against the powers of the evil one. Marriage ceremony
consisted of joining hands through the hole, a vow held as sacred as
the legal marriage of to-day. Pains in the head cured by inserting the
head in the cavity, cure of palsy in children. Children and adults
travelled many miles to secure relief in this way.
At the Mên-an-tol the curative effects could only be obtained by
crawling through the aperture, which is of considerable size.
As a rule, however, the aperture is much more restricted. The general
size of the holed stone and the position of the aperture in it may be
well gathered from the fact that almost all of them have been used for
gateposts, and are now to be seen fulfilling that function. In some
cases the old special use can be inferred, but in others this is more
difficult, as the stones have been shifted or slewed round, or the
ancient monument to which the sighting stone was directed has
disappeared.
The astronomical origin of the Mên-an-tol, which obviously has never
been disturbed, is quite obvious. Fig. 56 (from Lukis) shews that it was
arranged along the May year alignment, the advent of May and August,
February and November being indicated by the shadows cast by the stones
through the aperture on to the opposite ones.
To the south-west the alignment for the February and November sunsets
passes exactly over Chûn Castle.
The “Tolmen” near Gweek, Constantine, another famous holed stone 7 feet
9 inches high and with an aperture of 17 inches, is according to a
magnetic bearing I took last Easter parallel to the Mên-an-tol, and
doubtless was used for the same purpose.
[117] In Cornwall this is the name generally given to a monolith.