An Essay on the modern system of fortification adopted for the defence of the Rhine frontier : and followed in a greater or less degree in all the principal works of the kind now constructed on the continent, exemplified in a copious memoir on the fortress of Coblentz and illustrated by plans and sections of the works at that place / By lieut.-colonel J. H. Humfrey, K. S. F. of H. C. M. Service, formerly of the Royal staff corps and royal artillery..