These proportions are unlikely to have happened by accident, and one cannot help wondering whether the derived viewing altitude across the first bay, estimated at 9.42°, was not likewise deliberately chosen as a gradient of 1 in 6 (or 9.46°). There is much evidence from a later date for the use of such simple ratios. One can only make this assumption freely, on the other hand, if there was no other constraint, and there can be little doubt that there was one very important constraint accepted by the designers. The first four rows of stake holes on the northern side were almost certainly meant to be exactly at right angles to the axis—the average angle was around 89.8° even at the time of the excavation. This was surely the builders’ second precondition—the first being acceptance of the diagonal. It is unlikely that they waited until the old Bellatrix line (the axis) was at a perfect right angle to a one-in-six Sirius line, before setting up the barrow. Had they done so, however, they would only have been playing yet another round in a science of barrow-symmetry and precise alignment that one suspects was becoming an end in itself.
Skendleby: Giants’ Hills 1 and 2. Stars and Sun
While the focus of attention is Wessex practice, there are other important long barrows that are worth mentioning since they reveal so much in common with it. Two of these are at Giants’ Hills, Skendleby, Lincolnshire. Both Skendleby barrows were constructed using the technique of fences of stake posts, now emphatically holding multiple horizontals (hurdling), and not only single fence-top poles. Each barrow was at some stage fronted by a façade of heavy timber posts, which in the earlier case were used to mark the extreme directions of the rising of the midwinter Sun and the setting of the midsummer Sun. Skendleby 2 long predated Beckhampton Road, and seems to have set its perpendiculars towards far edges, as did that barrow. At a later stage two other early instances will be added to our list of long barrows with solar alignments.
The two Skendleby barrows are near neighbours on the same hillside—they are only 250 m apart—and are among fifteen or so long barrows on the Lincolnshire Wolds. Skendleby 1 (latitude 53° 13' 05") was excavated under the direction of C. W. Phillips in 1934, and Skendleby 2 (latitude 53° 12' 40"), in what amounted to a rescue operation, under the direction of J. G. Evans and D. D. A. Simpson in 1975–6. It is likely that each went through at least two distinctive phases, which it will be convenient to distinguish as Skendleby 1A and 1B, and Skendleby 2A and 2B, and so forth.
Both were almost wholly surrounded by ditches, and those flanking the barrows seem at first sight to have been by no means at equal levels. Had this been wholly true it would have meant that our fundamental assumption was inapplicable, and that our method would have needed to be applied, if at all, in a modified form. (To every observing altitude from one ditch there corresponds a unique ridge height and therefore a unique observing altitude from the other ditch. Given a complete ditch survey it would in principle be possible to extend the method to such cases, matching disparate observing levels.) In fact on closer examination it appears that a ledge was deliberately placed in the lower ditch to be at the level of the floor of the upper (see the left lower part of Fig. 38). This ledge was vital to the planning of the barrow: it was clearly cut to satisfy the general precept that observation must be at equal distances from the ridge, and from places at equal levels below it. As can be seen from the same figure, however, when the ditch was cut of necessity to a lower level, for materials, the possibility was retained of observing at precisely the same angle albeit from that lower level. At Skendleby 1 the same principle is to be seen in reverse (see the upper left of the same figure). Here the key positions for the planning of the ditch were in mid-ditch, but an additional place was provided on a wide inner ledge. Something similar was seen at the Horslip long barrow.
The excavation of Skendleby 1 was a model for its time—perhaps one day a return will be made to Phillips’ attempt to draft ditch contours—and the monument yielded good geometrical detail. Fig. 39 abstracts what from our point of view is the most important information. The façade, in what was described by Phillips as a revetment trench, is at R. The posts in it had been split, and the flats of the semicircles set against the outer curve, to the northwest, suggestive of a wall intended to be a solid curtain. H was a large hole, B a platform for the burial, and S a line of stones, perpendicular to the axis of the barrow.
FIG. 38. Important sections of the ditches at barrows 1 and 2 (in their final forms) at Giants’ Hills, Skendleby. Both barrows run close to contours on hillsides, and the fall of the ground across the barrows is easily appreciated here. A rough idea of likely mound forms is given by the lines of sight, astronomically derived. The upper section corresponds to the line XY in Fig. 39 and the lower to a roughly similar place on the similar barrow Skendleby 2. Key viewing positions at the planning stage were x, y, p, and q. Note the optional viewing positions, z and r, to the left (south west) of the sections.
Skendleby 2 had been severely damaged by long ploughing, but the mapping of the barrow was done meticulously, and radiocarbon dating produced no fewer than fourteen dates in all, covering a perplexing spread of time—almost two millennia. Its end-ditches were clearly meant for observation. There were actually two end-ditches at the northwest: the first had been filled in before a new one was cut about 10 m further from the façade. This might mean that the mound was at some stage lengthened—say from 60 m or less to 70 m. The former, as it happens, is the length of Skendleby 1. The deeper ditch to the front of the façade was well fitted to observation over the mound. The rough equality of the distances of observers, from side ditches to ridge, and from front ditch to façade, will eventually be used to confirm that there was at Skendleby 2 a set of three equal viewing angles.
FIG. 39. Outline of Skendleby 1 (upper figure). The contours are at 2 ft (about 60 cm) intervals, and although unnumbered, their change can be estimated with the help of Fig. 38, showing the section XY. The mound base (outer contour of hole H) is 236 ft above the Ordnance Datum. The positions of many of the revetting posts round the edge follow the conjectures of C. W. Phillips. The stake holes for the fencing of the bays, and collapsed poles, once tied to them, are at the northwest. The studied proportions of the southeastern end are intimated in the lower figure (drawn to a larger scale), where construction lines are conjectured. The width of one of our hypothetical bays is double the interval between revetting posts, that is, about 3 m.
These twin barrows provide us with an object lesson in the importance of precision, something that can be best illustrated by the fact that, while the barrows differ in direction by only a few degrees, and are of much the same form and dimensions, the star Deneb was much implicated in the design of one but not the other (Skendleby 2, but not Skendleby 1, which was begun several centuries later). There are some difficult problems here, not only internal, but of the relations between the two barrows. Even after two exemplary excavations, there is much simple but desirable surveying information that is lacking, and that might one day allow a more complete analysis.
The bowed form of the façade of Skendleby 1 seems to hint at a clever architectural device for holding back the soil of a mound. On these grounds it might be made the later of the two—and the astronomical arguments fall in with this idea. In both cases, a mere glance at the plans is enough to suggest that there are components of the barrows that are skewed with respect to the axes of the mounds. This should be enough to alert us to the presence of multiple celestial alignments.
Consider first Skendleby 2. The southern edge of the mound has been irretrievably lost, but long stretches of the northern edge are known in minute detail—for which the excavator’s report must of course be consulted—and a perpendicular to the first and best