A softer stone, which can be dressed with the hammer, may
be treated in two different ways: It may be shaped to fit closely,
without using any spalls to fill up the interstices, and, thus,
appear as a cut-out puzzle; this is called “cobweb rubble.”
However, the more dignified treatment is the squared, uncoursed
rubble, in which the blocks are cut to rectangular shape and the
joints pointed with a tool. Figures 5 and 6 illustrate these.
A wall built entirely of field stone depends upon the mortar
for its strength. It appears the best when the joints of the
surface are raked out, permitting a large part of the stones to
project outward. Figure 7 illustrates this kind of rubble wall.
When the rubble wall is built with very carefully squared stones,
and in regular courses, it partakes more of the monumental character
of ashlar work and draws away from the rustic value of rubble. In
determining the amount of cutting which is to be done, the character of
the building should be considered, remembering that the smoother and
more finished the wall, the more monumental is its appearance.
[Illustration: Fig. 6. Square uncoursed Rubble tooled joints