Whispering-gallery wave Whispering-gallery wave Whispering-gallery waves, or whispering-gallery modes, are a type of wave that can travel around a concave surface. Originally discovered for sound waves in the whispering gallery of St Paul’s Cathedral, they can exist for light and for other waves, with important applications in nondestructive testing, lasing, cooling and sensing, as well as in astronomy. Whispering-gallery waves were first explained for the case of St Paul's Cathedral circa 1878 by Lord Rayleigh, who revised a previous misconception that whispers could be heard across the dome but not at any intermediate position. He explained the phenomenon of travelling whispers with
Speyer Cathedral an interior of monumental power, albeit stark and prismatic when compared with contemporary French buildings, but one which conveys an impression of Roman "gravitas", an impression singularly appropriate for a ruler with the political pretensions of Henry IV." In the course of these modifications the cathedral was equipped with an external dwarf gallery, an arcaded gallery recessed into the thickness of the walls, and which is a natural development of the blind arcade. Such blind arcades were used extensively as decorations, lining internal and external walls of many Romanesque churches. At the east end of Speyer Cathedral the dwarf gallery