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Some features of the germination and dispersal of Juncus tenuis seeds are examined. The seedlings are well adapted for dissemination by human or animal agency and for colonisation of mud, hence its frequent appearance by tracks and roads. It may be a colonist from America, and has spread in the West of Britain more rapidly than in the east.

A new technique for the evaluation of precision surfaces using laser interferometry is presented. Laser interferometry creates a fringe pattern which contains information about the surface texture of the specimen. The technique presented compares the ideal fringe pattern to the actual fringe pattern to determine the height deviation on the specimen. In this paper, a simulation model is used to predict the fringe pattern for a given surface. The surface topography of a groove on a computer hard disk is then reconstructed from an experimentally obtained fringe pattern. The reconstruction process is verified by comparing the reconstructed surface to a photograph of the actual surface.