A book lands with an almighty thud on Astragal's desk. It is Alfonso Acocella's massive survey of Stone Architecture.
Among such impressive headings as 'Pseudosodomic opus quadratum', Astragal was bemused by 'Polygonal fiLesbianfl masonry'. Not wishing to be a prude, but given that mechanical elements are often described as having male parts and female parts, how would it fit together? It turns out to be a kind of masonry found on the island of Lesbos, whose stone is particularly suited to cutting into curvilinear blocks. So now we know.