The architecture of this period, although it was derived from Greek and Roman models, applied new principles, forming structures wholly different from the antique originals. Through many successive centuries the Ro-man school of art continued to suffer changes. From the fragments of edifices which were torn down to form new structures, arose new combinations. The transition styles which then prevailed were, from their characteristic peculiarities, designated as the Latin, the Byzantine, the Lombard, the Saxon, the Norman, and the Romanesque, together known as the old or round-arched Gothic. During the 4th century architecture had reached its lowest point. In the religious edifices of this period marked evidences exist of an utter want of artistic feeling. The sterling principles which had been the glory of Grecian and Roman schools were either forgotten or not understood. Arches with and without archivolts were made to spring immediately from the capitals of the columns. Orders were superimposed with broken entablature; in fact, this latter member was altogether done away with in some cases.

Grace was wanting in the mouldings and sculpture; the different orders were employed in the same peristyle, and the whole school of architecture became a prey to the general system of innovation which then existed. During this state of tilings hordes of barbarians invaded every province of the empire. This universal conflict was not calculated to give a new impetus to art, nor to promote its progress. Italy, however, under the Goth and Ostrogoth rule, evinced in some measure a renewed architectural zeal. Theodoric repaired the walls and drains of Rome, reorganized the comitivœ Romance (who guarded day and night the monumental structures of the capital), and by his own devotion to the arts, together with that of his daughter Amalason-tha, revivified the spirit of a fast perishing craft. - After the transfer by Constantine of the imperial seat to Constantinople, the arts were again successfully cultivated by the Greeks, who made free use of the architectural treasures left by the ancients. Then appeared the dome, the glory of the Byzantine school, supported by its pendentives highly ornamented with mosaic.

This principal feature of the By-zantine school induced their architects to aban-I don the Latin cross (which form had gradually grown out of that of the Roman basilica) in the plan of their churches, introducing instead the Grecian cross, whose branches are of equal . length. The dome no longer rested on circular walls, but was borne by four arches resting on pillars placed at the four angles, in plan. Pendentives were introduced in order to sustain the circular dome, as otherwise the triangular space in the four corners would have been left without support, the diameter of the dome being equal to one of the sides of the square. In some cases the corner pillars were square, presenting an angle only at the corners, thereby giving an extraordinary degree of lightness to the structure. The semicircular arch of the Ro-j mans was often elongated, in order to attain an equal height with different spans. The dogmas of the iconoclasts obliged the architects to seek | some other means than sculpture of enriching their temples; hence the profusion of mosaic | work. Their ornaments represented foliage in bass-relief and interlaced lines. The capitals | of the columns were square blocks similarly ' carved, tapering down at angles to join the circular shaft.

Under Narses and Belisarius the dome was introduced into Italy. The Byzantine style, whose chief promoters were Anthemius of Tralles and Isidorus of Miletus, also became the basis of the new Persian, Russian, and Sara-cen schools. We find its peculiarities existing during the middle ages in Greece, Italy, Sicily, Spain, Arabia, and India. Among the chief edifices of the Byzantine school are St. Mark's at Venice, San Vitale at Ravenna, and St. Sophia at Constantinople, the last being one i of the most magnificent of the eastern empire. - The Saracens and Moors introduced into Europe certain forms of architecture ! which, though differing in very many features i from the classic styles, were still founded on the remains of the Grecian school, blended with the oriental elements of the Byzantine. The chief peculiarity of these styles was in the form given to the arch. The Saracenic arch was of greater depth than width. The Moor-ish style was distinguished by arches in the shape of a horseshoe or a crescent. The Saracens and Moors are, however, so completely | one people, that it is with difficulty that the differences of their essential features can be discriminated.

Their mural ornamentations, styled arabesque, presented more varied designs of graceful and ingenious combinations of geometrical and floral traceries than had before been known. The reproduction of animated forms was prohibited by the Koran. Another striking feature of this school is the peculiar way in which they ornamented their pendentives, by a series of little niches placed one above another, covering not only the surface of the inner projecting angles, but forming at times the superentablature of the edifice. The numerous mosques, palaces, bazaars, tombs, and other edifices of the Moslems, existing throughout various parts of Europe, Asia, and Africa, attest the great similarity existing between this style and the Byzantine; this has been attributed to the employment of Greeks on their works. A fact worthy of note, also, is that the Moslem structures furnish examples of the pointed arches, whence according to many they were brought into Europe. - The Lombards, having possessed themselves of the northern part of Italy after the middle of the 6th century, there founded their kingdom.

Converted to Catholicism, they adopted the arts of the people they had vanquished; and, as in Lombardy there existed but few ancient temples whose materials could be employed in other structures, we find them originating a complete and systematized style, which at length pervaded all districts where the Latin church had extended its influence; the people of each country where it was introduced modifying it to suit their climate, customs, and wants. Its branches are variously known as the Merovingian, Carlo-vingian, Saxon, Norman, etc, which together were styled old Gothic, and out of which grew the pointed style, after the introduction into Europe of the pointed arch. During this epoch plain, banded, fluted, and polygonal columns, in spiral or zigzag, were clustered, broken, or knotted together. Their capitals were foliated or had various grotesque animals sculptured on them; they were supported on brackets variously carved, or rested upon the backs of animals, which replaced the pedestal. Every license was taken with the entablature, even to the suppression of it altogether. Against the jambs of arched openings were often placed numerous columns supporting the arched mouldings.