The number of these sepulchral remains scattered throughout the country is very great. Mr. Borlase enumerates them as follows: dolmens, certain, 780; chambered tumuli, 50; uncertain, 68--total, 898. Of these dolmens, Connaught has 248; Munster, 234; Ulster, 227; and Leinster, 71. The counties richest in these are--Sligo, 163; Clare, 94; Donegal, 82; and Cork, 71. The area of geographical distribution of these megalithic monuments is very wide. It extends from western Asia--Syria, Palestine, and Turkey--over north Africa, through south-east Europe, France, Spain, Portugal, over north Germany, and northern Europe. In France they reached a high degree of perfection. England and Wales furnish many examples similar to the Irish cromlechs; but they are rarely, if ever, found in Scotland. The question naturally suggests itself, How were a primitive people, with such rude mechanical means as they possessed, able to raise those huge stones into the positions in which they are now found? Several theories have been advanced, which may be briefly stated. It has been suggested that the great covering stones of the cromlech having been found _in situ_, they were undermined, and a chamber formed beneath by the removal of the earth. As the work progressed uprights were by degrees placed in position, of sufficient weight and strength to support the great covering stone. Instances are found in Ireland to which this theory might, perhaps, apply; but the method could not have been adopted in such cases as that of the Ballymascanlan cromlech, where the cap-stone rests on clear supports 8 or 9 feet high. The plan suggested by the King of Denmark has been accepted by many, and it may have been adopted in some cases. In this, the supporting stones having been placed in position, an inclined plane or bank of earth would be raised, sloping from the level of the uprights to the ground. Up this the roofing stone would be worked, over blocks of timber placed side by side, by means of levers, wedges, and haulage. The absence of all traces of such banks in existing cromlechs, and other considerations, have been urged against this method of raising these structures. On the ground that all cromlechs were originally of the ‘giant’s grave’ order, Mr. Borlase urges the theory that the cap-stones were raised one by one, the largest first, until it fell into its place upon the highest uprights. He considers that the disarrangement in the lines of the side stones, and the presence occasionally of buttresses, support this view. By using beams of timber and rollers it was possible, with great and united human strength, to lever very heavy rocks, bit by bit, into position.