134 
THE PRINCIPAL FLOOR. 
Mosaics. Table Case 56. 
Portrait of the Emperor of Russia, &c., on Gallery stairs, eastern- 
side. Head of Christ, &c., on western side. 
In this Case are some examples of ancient Roman tesselated 
pavements, which show the manner in which they were con- 
structed, and the kind of design which is usually found. A 
portion of a mosaic pavement found at Halicarnassus is mounted 
on the western staircase. 
The art of manufacturing glass mosaics was practised in old 
Rome, and the modern city is still the seat of this manufacture. 
The manufacture has, however, as might he expected, varied 
somewhat in character. As at present practised, thin rods of 
easily fusible glass of every variety of colour are prepared for 
the purpose. From masses of coloured glass are formed, first, 
slabs, and then the little rods exhibited ; the artist softens these 
in the flame of his lamp, draws out the rod into a thick thread, 
and breaks off a piece of the thickness of the intended picture. 
The design of the picture is copied from a cartoon, and the pieces 
are placed in proper order on a sheet of copper, covered with a 
cement which serves for fixing the picture ; when the whole 
slab is covered, the surface, which is uneven and unsightly from 
the unequal lengths of the rods, is ground and polished. After 
the removal of the polishing powder the interstices between the 
rods are filled with wax, which corresponds in colour with the 
different parts of the picture. Glass mosaics are now also 
manufactured in Venice. A large example of Byzantine mosaic 
is the Head of Christ, on the western staircase : whilst on the 
opposite side are two modern Roman mosaics, of large size, one 
being a portrait of the Emperor of Russia : this work was. 
executed in 1828, and presented to the Museum by the Cavaliere 
Barbieri of Rome. 
