d to particular points of the wall, sometimes forming a
great sloping rampart along its base, are frequent in buildings of
countries exposed to earthquake. They give a peculiarly heavy outline to
much of the architecture of the kingdom of Naples, and they are of the
form in which strength and solidity are first naturally sought, in the
slope of the Egyptian wall. The base of Guy's Tower at Warwick is a
singularly bold example of their military use; and so, in general,
bastion and rampart profiles, where, however, the object of stability
against a shock is complicated with that of sustaining weight of earth
in the rampart behind.

Sec. V. 3. Prop buttresses against dead weight.

This is the group with which we have principally to do; and a buttress
of this kind acts in two ways, partly by its weight and partly by its
strength. It acts by its weight when its mass is so great that the
weight it sustains cannot stir it, but is lost upon it, buried in it,
and annihilated: neither the shape of such a buttress nor the cohesion
of its materials are of much consequence; a heap of stones or sandbags,
laid up against the wall, will answer as well as a built and cemented
mass.

But a buttress acting by its strength is not of mass sufficient to
resist the weight by mere inertia; but it conveys the weight through its
body to something else which is so capable; as, for instance, a man
leaning against a door with his hands, and propping himself against the
ground, conveys the force which would open or close the door against him
through his body to the ground. A buttress acting in this way must be of
perfectly coherent materials, and so strong that though the weight to
be borne could easily move it, it cannot break it: this kind of buttress
may be called a conducting buttress. Practically, however, the two modes
of action are always in some sort united. Again, the weight to be borne
may either act generally on the whole wall surface, or with excessive
energy on particular points: when it acts on the whole wall surface, the
whole wall is generally supported; and the arrangement becomes a
continuous rampart, as a dyke, or bank of reservoir.

Sec. VI. It is, however, very seldom that lateral force in architecture is
equally distributed. In most cases the weight of the roof, or the force
of any lateral thrust, are more or less confined to certain points and
directions. In an early state of architectural science this definiteness
of dire