The determination of the variance of local grammage in random fibre networks by the line method

An approximate technique known as the line method, used to determine the variance of local grammage in random fibre networks, was presented by Corte and Dodson in 1969. In their original article, and in several subsequent publications, the derived equations have been published incorrectly. Here, these equations have been rederived following Corte and Dodson and are stated correctly. The use of the line method to account for the influence of fibre length distribution is also presented. Comparison is made with the established analytic determination of the fractional between zones variance derived by Dodson. Agreement between the techniques is excellent.