The heaviest part of the foundations of buildings settles most, and
leaves the lighter part above it separated from it.

And the soil which is most pressed, if it be porous yields most.

You should always make the foundations project equally beyond the
weight of the walls and piers, as shown at _m a b_. If you do as
many do, that is to say if you make a foundation of equal width from
the bottom up to the surface of the ground, and charge it above with
unequal weights, as shown at _b e_ and at _e o_, at the part of the
foundation at _b e_, the pier of the angle will weigh most and
thrust its foundation downwards, which the wall at _e o_ will not
do; since it does not cover the whole of its foundation, and
therefore thrusts less heavily and settles less. Hence, the pier _b
e_ in settling cracks and parts from the wall _e o_. This may be
seen in most buildings which are cracked round the piers.