The homes of the cave men were located, when possible, where the refuge of safety overhung closely the river's bank, and where the non-climbing animals must pass along beneath them, but, even at that period of few men and abundant animal life, there had developed an acuteness among the weaker beasts, and they had learned to avoid certain paths that had proved fatal to their brethren. They were numerous in the plains and comparatively careless there, relying upon their speed to escape more dangerous wild beasts, but they passed rarely beneath the ledges, where a weighty rock dropped suddenly meant certain death. It was not a task entirely easy for the cave men to have meat with regularity, flush as was the life about them. New devices must be resorted to, and Ab and Oak were about to employ one not infrequently successful.
The clam of the period, particularly the clam along this reach of the upper Thames, was a marvel in his make-up. He was as large as he was luscious, as abundant as he was both and was a great feature in the food supply of the time. Not merely was he a feature in the food supply, but in a mechanical way, and the first object sought by the boys, after their plan had been agreed upon, was the shell of the great clam. They had no difficulty in securing what they wanted, for strewn all about each cave were the big shells in abundance. Sharp-edged, firm-backed, one of these shells made an admirable little shovel, something with which to cut the turf and throw up the soil, a most useful implement in the hands of the river haunting people. The idea of the youngsters was simply this: Their rendezvous should be at that point in the forest nearest the clump of trees standing solitary in the valley below. They would select the safest hours and then from the high ground make a sudden dash to the tree clump. They would be watchful, of course, and seek to avoid the class of animals for whom boys made admirable luncheon. Once at the clump of trees and safely ensconced among the branches, they could determine wisely upon the next step in their adventure. They were very knowing, these young men, for they had observed their elders. What they wanted to do, what was the end and aim of all this recklessness, was to dig a pit in this rich valley land close to the clump of trees, a pit say some ten feet in length by six feet in breadth and seven or eight feet in depth. That meant a gigantic labor. Gillian, of "The Toilers of the Sea," assigned to himself hardly a greater task. These were boys of the cave kind and must, perforce, conduct themselves originally. As to the details of the plan, well, they were only vague, as yet, but rapidly assuming a form more definite.