Another interesting detail. The holes in the stone dolmens were closed by special plugs, bushings. Their shape is very interesting. They are reminiscent of ultrasonic transducers used in modern technology to focus the ultrasonic flow. As the radiators in modern devices used ceramic plates, moving the focal region of the transducer is achieved by moving the plate and change the radiator shell. In the ancient "radiators", appears to have played a major role composition of the rock, which is manufactured from the bush, and the geometry of the surface.
How was the process of setting up a dolmen at the desired frequency sound? What are the standards used in this? Some material for reflection on this issue given the archaeological finds. In those relatively few cases where a megalithic structures found in ancient tombs, among the items found there is usually present ceramics (pots) with a specific ornament. In British megalithic tombs — is grooved pottery in zapadnokavkazskih dolmens — pots with ornaments in the form of zigzag lines. It also sometimes find bronze hooks, covered with convex pattern in the form of snakes and twists.
J. Wood notes that this particular ceramic (grooved) was the exclusive prerogative of the priestly class. Apparently, when the dying priest, served the megalithic "apparatus", it (the priest) were buried in a special sign of veneration in this building together with all its "sacred" objects. Ornament on pots and wands, these zigzag lines, and were the standard, which is customized to the parameters in the configuration process dolmen. At the same pot of zigzagopodobnym patterns could be used as a receiver of sound radiated by the dolmen. Coating the emitting wall zigzags dolmen, the priest sought the maximum sound volume pot-standard. The parameters were taken from the standard zigzag pattern on the pot or wand. Themselves these standards were copied from older models, so this information is passed on from generation to generation, even in the absence of a written language.
The obvious question is — who is originally set these frequency standards, who developed the principles of construction of dolmens and other megalithic? It is clear that the level of knowledge of people in the UK, France or the Caucasus in the Stone Age was not sufficient for this purpose. It was impossible to open or accidentally. It remains to prevent the possibility of contact people in ancient times with the carriers of this knowledge — the representatives of some highly advanced extraterrestrial civilization.