Two charges hang from pendulums whose supports can
be moved closer or further apart by an external agent.
The charges have the same sign, and therefore repel.
An external agent tries to move the supports (from which
the two positive charges are suspended) together. The
force of gravity is pulling the charges down, and the
force of electrostatic repulsion is pushing them apart
on the radial line joining them. The behavior of the
electric fields in this situation is an example of an
electrostatic pressure transmitted perpendicular to
the field. That pressure tries to keep the two charges
apart in this situation, as the external agent controlling
the pendulum supports tries to move them together.