Some hydromechanical systems are investigated by applying the dual
integral equation method. In developing this method we suggest
from elementary appropriate solutions of Laplace's equation, in
the domain under consideration, the introduction of a potential
function which provides useful combinations in cylindrical and
spherical coordinates systems. Since the mixed boundary conditions
and the form of the potential function are quite
general, we obtain integral equations with $m$ th-order Hankel kernels. We then discuss a kind of approximate practicable
solutions. We note also that the method has important applications
in situations which arise in the determination of the temperature
distribution in steady-state heat-conduction problems.