DOME ((W. dom.., Fr. thiate, from Lat. domus, Gk. 86/10s, °('hurch Slay. dorms, Skt. damn, house; connected ultimately with 0110. zintbor, Ger. Ziatimr, Icel. AS., Engl. timber: the word is also influenced by Lat. dome, Gk. 6,17' rm. house). A term in architecture bearing a twofold mean ing. It is loosely used. after the fashion of the German Own and Italian Doonto, to designate a cathedral or some other building of importance, but its only genuine English scientific meaning is th:it of a spherical or polygonal covering of a building. strietly it only the outer strueture or surface of such a cowering, the inner strit•ture or surface being a cupola (Tv. i ; but in general usage dome Means the en tire cowering. It may he of any material—wood. stone. metal, earthenware, etc. It may be built of a single mass, like the Pantheon, or a double or even triple series of concentric coverilitys, like Saint Peter's in !tome or Saint \lark's in Veniee. \l'here there are several such connected surfaces, the outer does not necessarily follow the outline of the inner one. In fact, in many such cases as Saint Mark, and even more so in the Russian churches with their outer bulbs, there is very little resemblance of outline. Sonic domes curve directly from their base; others arc raised on a special conical base called a dram.
Historically the dome falls into two great divi sions—the period before and after the invention of the dome on pendentives; or, roughly speaking, the period before and after Saint Sophia in Con stantinople. It was an early form, though not as early as the tunnel vault. It was known to the Assyrians and Persians, (we do not yet know of its use by Egyptians or Babylonians), who used it Dyer houses and palaces. sometimes with low. semicircular outline. sometimes with high ovoidal or pointed outline. These (buttes were made usually of brick and rested on solid walls. Where these walls were square. the transition was effected by bracket-like projections at the base of the dome. The Pelasgie and Myeen:ran tribes also used the dome, but they built it of stone, and its supporting walls were always cir cular. The dome itself was often merely a false dome built up of overlapping horizontal stone courses, with their overlap subsequently cham fered off. Such was the Tholos of Atreus at Mycelia% The early Italian tribes. as well as those of Grevee. used this kind of dome, which appears in Etruria and Latium (e.g. VetuIonia), where even appear signs of the ()dental form. The 'Romans, however, appear to have been the first to give really monumental expres sion to the dome. With them it was a bell-like mass of concrete casting resting solidly upon its circular base. as at the Pantheon. built by Agrippa, which remains the largest masonry dome in the world, 112 feet in diameter. This dome was faced with brick. and its walls inter penetrated by interacting arches which served to hold the concrete filling until it hardened. Such domes were built on wooden centrings. Smaller examples are the Temple of Minerva. at Medice, near Rome, and some of the halls in the thernue. This form was popular in the Christian period for mailsoleums (Santa Costanza. Home), and sometimes for churches ( San Stefano Rotondo. Nome). but especially for baptisteries. in the sixth (•entury, after tentative attempts at Bovra and Ezra in Syria, at San Vitale, Ravenna. San Lorenzo, Milan, and Saha Sergius and Bacchus in Constantinople, the problem of suspending the dome on pendentive: connected with piers, instead of uu solid walls, was solved in the ('lurch of Saint Sophia, Constantinople. Tn this way not only could the dome be used over any kind of ground plan, but several domes COIN 1W abi.VI• the satin. interior. This was an invention. therefore, of Byzantine arehitecture. The pcmicntir,s (q.v.) were curved triangular spaces bounded by arcs of (dudes connecting four souare planes interseeting, the circle at the base of the dome. 'Hie arches in these square planes were themselves supported on piers. Such domes were built up of independent material. not east in concrete, and the units Were usually hollow conical tile made of speeiall• light earth, to less en the weight. The skill shown in Saint Sophia
was never afterwards duplicated, other Byzan tine domes being much smaller and usually ar ranged in groups. 'fit' lateral thrust of these domes was received on buttresses or on the vaults of galleries and aisles. The Byzantine dome was originally low, but as the :Middle Ages progressed, its drum increased in height until it became al most tower-like in outline, as in the churches of Salonica, in Greece, and in late examples in Con stantinople. The Arabs copied the dome from both Persian and Byzantine models. That of the Mosque of Omar in Jerusalem is probably the earliest extant. They also used it especially for mausoleums, calling them by the term kubba (cupola). There arc many of these in Cairo, where the mausoleum-mosques are surmounted by some of the fittest :Mohammedan domes ex tant, such as that of haft Bey. The outline of these domes is sometimes that of a reverse curve —a new form. The :Mohammedans invented an elaborate system of corbeling as a substitute for the regular pendentive. Their most colossal domes are in India: those of the Jumma Musjid and the Tomb of Malmiud in Bijapur are among the largest in the world, and that of the Taj Mahal in Agra among the most beautiful. The Turks also reproduced the dome of Saint Sophia more monumentally than had been done by the Byzan tines themselves (witness the mosques of :Moham med 11. and Solyman). Meanwhile the Byzan tine dome had been imitated in medieval Europe: in Italy, in Venice (Saint Mark), Padua (San Antonio), Ancona (cathedral), Pisa (cathedral), Palermo, and in Calabria : iu France, through out Nrigord and the neighboring region etc.), with scattering examples elsewhere. The so-called Gothic dome is a ribbed construc tion, originating in France, derived by com bining this Byzantine dome with the ribbed Gothic groin vault. The dome of the Renais sance was developed out of a mixture of medieval and Roman elements. Its earliest masterpiece, that of the cathedral in Florence, was planned in the Gothic period on medieval lines, but perfected by Arnolfo through his study of Roman archi tecture. The dome entered more generally hence forth into architecture than it had done before in the West. Its greatest examples are those of Saint Peter's in Rnme, by Michelangelo. and of Saint Paul's in London, by Wren: though other fine examples are Salute, in Venice, by Long hena; the lnvalides, by Mansart, and the Pan th-on, both in Paris. The dome of Saint Isaac's Cathedral in Saint Petersburg is a sham struc ture of cast iron, which is a material that has been used in modern times for the construction of several colossal domes, such as that of the Vienna Exhibition (360 feet). Domes built of separate units—stone, brick, or tile—require no centring such as was necessary in Roman domes, but could be built up by the simple superposition of concentric rings. It has been found that point ed domes are as much stronger than hemispherical as the pointed is stronger than the round arch. Early domes like the Pantheon received light merely through an unprotected opening in the apex: later this was protected by a lantern, and at Saint Sophia for the first time a row of win dows was opened in the base. It was this devel opment of a clearstory at the base that led to the heightening of the drum. The following are the inside diameters of some of the larger domes: Pantheon, 142 feet: cathedral. Florence, 13S14. feet: Saint Peter's, Rome, feet; Tomb of Mahmud. Bijapur, 137 feet: Saint Sophia. Con. stantinople. 105 feet ; San Carlo, Milan. 105 feet : Saint Paul's, London, 102 feet: the Capitol, Washington (constructed of iron), 96 feet; In valides, Paris, 92 feet.
Consult: Choisy, Cart de be ehez les Ro mains (Paris, 1573); hi., L•art de luitir chez les llyzanlins (Paris, ISS3) Franz-Paseha, "Die Baukunst des Islam," in Durm, Handbuch der .1n:hill:Our (Stuttgart. 1896) : Isabelle, Les (di flees eireulaires ct les d(imes (Park, 1555 ) ; also the various monographs on Saint l'eter's, Saint Paul's, etc. See Curol.A.