London.--_From the Architect_.]

By T.R. SPENCE.


I do not propose to enter into any historical details as to the first
and subsequent application of mosaics. In a general sense we understand
mosaic as a combination of various more or less imperishable
materials--fixed together by cement or other adhesive substances--and
laid over walls, floors, etc., with a view to permanent decorative
effect. The substance of the tesseræ is of many kinds, namely, glass,
cheap and precious marbles, hard stone, and burnt clay, these mentioned
being mainly in use for architectural purposes. For decorative schemes
we collect as many gradations of color as are obtainable in such durable
materials in their natural or manufactured state, and thus form a color
palette which we regard in the same sense as a painter would his
pigments.

Of course, the first proceeding is to prepare a design on a small scale,
which shall embrace your notions of color only. Then follows a
full-sized cartoon, which I need hardly add shall embrace your best
efforts in drawing. A tracing is made of the latter and transferred to
sheets of cardboard. This cardboard is cut to the size of certain
sections of your design, and, for convenience, should not be more than,
say, 20 in. square. Of course, it will not always be square, but will
bear the same relation to your complete cartoon as a map of the counties
would to that of all England. Now, working from the small design (of
color), the tesseræ are cut to the forms required, laid face downward,
and glued on to the cardboard sections containing your enlarged cartoon.
When the design is all worked out on these sections they are ready for