The “clapper” bridges over Dartmoor rivers are not difficult to study; their construction resembles that of cromlechs and Stonehenges. Their piers were evolved from menhirs, and their table slabs from the mass of rock forming the horizontal member of a cromlech. Nor is it difficult to suggest the evolution through which the clapper bridges have passed, for on Dartmoor itself the evolution is plainly suggested by the rude bridge at Okery and by the single slab at Walla Brook. Any primitive farmer of the Bronze Age had sense enough not merely to put a ledge of granite across the Walla Brook, but to span wider rivers by using menhirs to support large blocks of granite. Timber would not be used, since trees were very scarce on Dartmoor, while granite was so abundant that it must have been very troublesome to farmers.
Now the pastoral life of the Bronze Age was very active in the Dartmoor settlements; all antiquaries make much ado over this fact, yet they fail to see that the circulation of this farm life, the movement here and there of flocks and herds, required bridges, for the rivers then were not less wayward than they are now. Without bridges the farms would have stagnated. And another thing also needed the help of bridges: many domestic fires burnt a great deal of peat and wood, and wood had to be imported from neighbouring districts, probably in exchange for live stock. So, to visualise the farm life is to make it dependent on a ceaseless movement to and fro over very freakish rivers, which after rains and thaws were exceedingly turbulent and perilous. Deep gorges have been worn in the rocks through which the rivers flow; this alone is enough to prove that such wild rivers could not be forded by the tiny sheep and the small cattle of the Bronze Age. Even in mediæval times, as Thorold Rogers has proved, sheep were about as big as Mary’s little lamb; they were bred because their wool was the wealth—the Golden Fleece—that made England prosperous; and yet their cultivation failed to add to their national value by increasing their size. Sheep of the Bronze Age were probably smaller still; and how were they to cross the Dartmoor rivers unless bridges were built? Could sheep in those days swim like ducks, or did they float as naturally as logs? And since bridges must have been made here and there in order to keep the farming life from ruin, are we to suppose that the abundant granite blocks would not be used for piers and table stones? Are we to forget the instinctive delight in rude stonework shown everywhere by the dusky, short-statured race which for convenience we call Iberian?
The research of antiquaries may be good or bad. What has it done for the life of these clapper bridges? Has it proved that the present ones are probably younger than the Middle Ages, but that they had many predecessors going back to pre-Roman times? On the other hand, have antiquaries proved that in the Middle Ages a primitive phase of building was revived in Dartmoor, partly because it was good enough for the traffic, partly because it was inexpensive? The absence of lime on Dartmoor would influence the mediæval settlers and govern their building work. But in this discussion it matters not whether the present bridges be old or young; in either case they represent primeval methods. Between the Bronze Period and the Middle Ages all the earliest slab bridges may have disappeared; if so, then settlers on Dartmoor brought with them knowledge enough of cromlechs to recall the Iberian stonecraft, just as in modern times architects have revived phases of Gothic and phases of Classic. Every possibility is entertaining, but why is it that antiquaries in their remarks on the clapper bridges try to be elusive as well as dogmatic? For example, Mr. William Crossing is of opinion that the larger clapper bridges have had their age overestimated probably because their rough and massive appearance makes them very striking. Why “probably”? He adds that they are mostly in the line of pack-horse tracks, and were probably built by farm settlers. “Probably” again! Yet he gives no evidence. Even Mr. Baring-Gould is equally dogmatic in devious assertions that have no value to any architect. Like Mr. Crossing, he attributes the “clappers” to the period of pack-horses, and sees nothing in them to indicate a great antiquity. What next? Is primitive stonework insufficiently antique whatever its age may be? And who is to estimate the age of rude granite blocks?
I have summed up with fairness the views of architects, and they ought to hold the field in the judgment of all pontists. The antiquarian talk about pack-horse tracks has no cogency, for the prehistoric tracks over Dartmoor are the first pathways along which the controversy must ramble. A pontist, then, when visiting Dartmoor, has to do four things.
1. To visualise the farm life of the Bronze Age;
2. To reconnect it with the rivers and with the necessary trade in wood for household fires and for tool handles;
3. Then he will realise that bridges were essential, and that they would be made with the granite blocks which Nature had provided.
4. Then, too, he will see that the larger clapper bridges are merely flat cromlechs built over water, and that it matters not when the present ones were put up, since their main interest is their descent from those rude monuments of stone in which the Iberian people commemorated their cult of ancestors, their reverence for the sacred dead.
Near Postbridge, over the East Dart, there is a very bold clapper with three heavy table slabs, each of which is about 15 ft. long and 6 ft. wide. Two piers rise out of the water; each is a pile of granite menhirs that lie flat in the river with their ends looking up-stream and downstream. The abutments also are layers of granite, and in one abutment the stones are long enough to support on land a very large cromlech. Samuel Smiles believed that this bridge had “withstood the fury of the Dart for full twenty centuries,” but there was no need to challenge antiquaries by making a rash statement. For the rest, we must bracket these Dartmoor structures with two other kinds of slab-bridges—those in the valley of Wycollar ([p. 60]), and those in Spain, at Fuentes de Oñoro. My friend Mr. Edgar Wigram writes to me as follows about the Spanish variety:—