In the spring of 1971, Reinier Tirnrnan visited the University of Delaware during which time he gave a series of lectures on water waves from which these notes grew. Those of us privi­ leged to be present during that time will never forget the experience. Rein Tirnrnan is not easily forgotten. His seemingly inexhaustible energy completely overwhelmed us. Who could forget the numbing effect of a succession of long wine filled evenings of lively conversation on literature, politics, education, you name it, followed early the next day by the appearance of the apparently totally refreshed red haired giant eager to discuss our mathematical problems with keen insight en remarkable understanding, ready to lecture on fluid mechanics or optimal control theory or a host of other subjects and ready to work into the evening until the cycle repeated. He thought faster, he knew more, he drank more and he slept less than any of us mortals and he literally wore us out. What a rare privilege indeed to have participated in this intellectual orgy. Tirnrnan's lively interest in almost every­ thing coupled with his buoyant enthusiasm and infectious op­ timism epitomized his approach to life. No delicate nibbling at the fringes, he wanted every morsel of every course. In these times of narrow specialization truly renaissance figures are, if not extinct, at least a highly endangered species. But Tirnrnan was one of that rare breed.