Soil Mechanics -- to Soil Mechanics -- Lower bound collapse theorem and lack of normality of strain rate to yield surface for soils -- Proceedings of the Geotechnical Conference OSLO 1968 -- The double sliding, free rotating model for granular assemblies -- Photoelastic verification of a mechanical model for the flow of a granular material -- Elasto-plastic version of the double sliding model in undrained simple shear tests -- Improvement of the lowerbound solution for the vertical cut off in a cohesive, frictionless soil -- Application of the calculus of variations to the vertical cut off in cohesive frictionless soil -- A variational fallacy -- Consolidation around pore pressure meters -- Application of stress functions to consolidation problems -- Consolidation models consisting of an assembly of viscous elements or a cavity channel network -- Verification of the use of peak area for the quantitative differential thermal analysis -- A capacitative cell apparatus -- Étude photo-Élastique d'un empilement de disques -- Flow and Transport in Porous Media -- to Flow and Transport in Porous Media -- Singularity distributions for the analysis of multiple-fluid flow through porous media -- Moiré patterns of the membrane analogy for ground-water movement applied to multiple fluid flow -- A many-valued hodograph in an interface problem -- Generating functions in the theory of flow through porous media -- Vortex theory for multiple fluid in three dimensions -- The simultaneous flow of fresh and salt water in aquifers of large horizontal extension determined by shear flow and vortex theory -- L'entrainement de particules par le courant intersticiel -- Longitudinal and transverse diffusion in granular deposits -- Discussion of "Longitudinal and transverse diffusion in granular deposits" -- Transverse dispersion from an originally sharp fresh-salt interface caused by shear flow -- The tensor character of the dispersion coefficient in anisotropic porous media -- Dispersion in fissured rock. This book contains an overview of the most relevant scientific contributions of Gerard de Josselin de Jong to the development of both Soil Mechanics and Transport in Porous Media. The volume comprises a selection of papers by de Josselin de Jong as they were published in the international scientific literature. In addition, some unpublished, but higly relevant work has been included. Most of the papers of de Josselin de Jong are concerned with issues related to soil mechanics. This is not surprising, considering the fact that he worked at Delft Soil Mechanics Laboratory and given the nature of his chair at Delft University of Technology. But occasionally he made an excursion to the area of flow and transport in porous media. It characterizes his ingenuity that most of these excursions led to papers that are now classics in the field. The editors have chosen to divide his key publications into a group devoted to soil mechanics and a group devoted to flow and transport in porous media. The selected papers were published in the period 1950-1990. They clearly demontstrate the development of ideas and the profound contibutions of de Josselin de Jong. Each paper is a jewel on its own. He has an extremely original way of reasoning and illustrated intricate concepts and mechanisms with the aid of his famous hand-made drawings. In particular young scientists will enjoy reading these papers because important parts of today's porous media research find their roots in them, and because many questions raised by de Josselin de Jong are still open and subject to current investigations. Audience This volume is intended for scientists, engineers, and students working in geohydrology, geotechnical engineering, soil mechanics, environmental engineering, and transport in porous media.