What Is the Whispering Gallery of St Paul’s Cathedral?
The whispering gallery is one of the most famous features of Sir Christopher Wren’s great master piece, St. Paul’s Cathedral in London. It is the place where whispering-gallery waves were first discovered by Lord Rayleigh c. 1878. If you speak in this gallery, which runs round the inside of the great dome, the sound waves of your voice will be carried round to the opposite side of the gallery because the waves are prevented from going outwards by the stones lining the circular wall.
The great dome of St. Paul’s is really two domes – an outer dome with a diameter of 148 feet and an inner dome with a diameter of 103 feet. A hollow cone of brick work between them supports a steeple – like structure in six diminishing stages culminating in the ball and cross. The top of the cross is 404 feet above the ground.
St. Paul’s has been acclaimed as the most magnificent domed building of the Renaissance period. It replaced the Norman Cathedral which was destroyed in the Great Fire of London in 1666, and whose tower and spire were 124 feet higher than the present building.
The foundation stone of the new St. Paul’s was laid in 1675 and 35 years later the final stone of the cupola was put into position. Great craftsmen were employed on the interior decoration. Francis Bird carved the Conversion of St. Paul over the great pediment. Grinling Gibbons, one of England’s and the world’s finest woodcarvers, worked on the choir stalls, and the wrought iron work was done by Jean Tijou, the renowned ironsmith.
During the Second World War, St. Paul’s was hit three times by bombs, the most serious damage being the destruction of the high altar on the night of October 10, 1940. The new high altar was dedicated as a British Commonwealth war memorial in May, 1958.
The tombs of many famous men – Nelson, Wellington, Roberts, Jellicoe and Beatty – are either in the Cathedral or in the crypt beneath. Wren, too, is buried there, and his epitaph is inscribed in Latin over the north door. It is Si monumentum requiris, circumspice – if you seek his memorial, look around you.
How Does Sound Travels Around the Whispering Gallery of St Paul’s Cathedral?
A whispering gallery is most simply constructed in the form of a circular wall, and allows whispered communication from any part of the internal side of the circumference to any other part. The sound is carried by waves, known as whispering-gallery waves, which travel around the circumference clinging to the walls, an effect that was discovered in the whispering gallery of St Paul’s Cathedral in London.
The extent to which the sound travels at St Paul’s can also be judged by clapping in the gallery, which produces four echoes. Other historical examples are the Gol Gumbaz mausoleum in Bijapur and the Echo Wall of the Temple of Heaven in Beijing. A hemispherical enclosure will also guide whispering gallery waves. The waves carry the words so that others will be able to hear them from the opposite side of the gallery.
The gallery may also be in the form of an ellipse or ellipsoid, with an accessible point at each focus. In this case, when a visitor stands at one focus and whispers, the line of sound emanating from this focus reflects directly to the focus at the other end of the gallery, where the whispers may be heard.
In a similar way, two large concave parabolic dishes, serving as acoustic mirrors, may be erected facing each other in a room or outdoors to serve as a whispering gallery, a common feature of science museums. Egg-shaped galleries, such as the Golghar Granary at Bankipore, and irregularly shaped smooth-walled galleries in the form of caves, such as the Ear of Dionysius in Syracuse, also exist.