Sentence:  There is another feature of this proverbial place which seems to have contributed to the phrase's significance—that is, "the Blarney stone". [...] There is one stone, on the very battlement of the castle, forming the outward surface, the <WSD>machicolation</WSD>, or opening, through which stones, hot water, melted lead, or anything of that ardent character used, long ago, to be pitched on the heads of people coming after their cattle, and trying to beat in the outer gate. [...] To kiss it, a man should be held by the heels, dipped through the <WSD>machicolation</WSD> with his head about a hundred feet or so from the ground, and his life in the hands of a great many jokers, holding on desperately by the battlement and the man, and wishing the latter all manner of mellifluousness and good luck for the remainder of his life! 
Meaning of the word marked with <WSD> tags:  An opening between corbels that support a projecting parapet, or in the floor of a gallery or the roof of a portal, of a fortified building from which missiles can be shot or heated items dropped upon assailants attacking the base of the walls.