The present paper considers the prediction of the conductivity

and dielectric constant

of a lossy dielectric material (e.g. concrete) when the material is altered by the addition of a large number of short thin metal fibers homogenously but randomly disposed. The aim is to calculate these quantities as a function of the corresponding quantities

and

of the unaltered material, and of the shape, size, conductivity and quantity of the metal fibers or wires. An approximate solution of this problem has been obtained, in a form suitable for machine calculation.