Cross-sections of acoustic vases found in Swedish and Danish churches, with, on the left in each case, (a) front appearance in wall with block of wood inserted to constrict mouth of jar, (b) front appearance of pierced stone cover, (c) cross-section, to a
Cross-sections of acoustic vases found in Swedish and Danish churches, with, on the left in each case, (a) front appearance in wall with block of wood inserted to constrict mouth of jar, (b) front appearance of pierced stone cover, (c) cross-section, to a
