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all the projection  of surface and variety of outline   which   gave boldness,
elegance, and a charming propriety to the Grecian orders, were omitted, and
the new capitals mounted on round shafts, had no other effect than would
be
produced by rough blocks rudely adorned with foliage and basket work. The
form  of the arch was still more altered.   In all previous examples it had
been made semicircular, the terminations of the curve resting on the supporting
columns. The necessity of an arch which might be varied to suit the height
of the column that was to be employed, was probably more felt at this
than at any former period. The semicircular arch, which of course required
a correspondent regularity in all the proportions of the column, was therefore
superseded by the introduction of arches whose abutments were lengthened
at pleasure to suit the column that was to be introduced.       Some of these
arches described a large, and others a small segment, while the imposts
also from  tle opposite sides were made to curve towards each      other
in a
form  something  resembling that of a horse-shoe.      Another and still
more
singular change was effected by the introduction of pointed arches, somewhat
similar to those afterwards employed in Gothic architecture. In the churches
of the period, this arch may be seen intermixed with the round arch both
at Constantinople and at Venice.
  The church of St. Mark in Venice, which was commenced about the year 960
of the Christian era, is one of the most interesting -structures of the period,
and
its interior demands for a moment our attention, as the best illustration
that
can be given of the prevailing taste in decorations.   Greek artists were
em-
ployed in the preparation of the most costly marbles and the richest mosaics,
the central parts of which consisted of large compartments of serpentine
and
porphyry, surrounded by borders inlaid with precious marbles in panels of
the
same material, but of a pure white.       The altar, the bishop's throne,
the
screens, and other parts of the early Christian sanctuary, were thus decorated;
and in those smaller members of the design, such as the shafts of columns,
in which it was impossible to introduce the compartments of serpentine and
porphyry, narrow ribbons of purple and gold were inserted.