This issue is a Festschrift to Dr A. J. (‘Arch’) Dyer, the distinguished Australian micrometeorologist. In these introductory notes, the intent is to summarize Arch’s contributions in micrometeorology, and especially in the development of flux-gradient relationships, not in depth but in sufficient detail to give the unfamiliar reader an idea of the thoroughness of his work. Arch’s own review of the history of eddy flux measurement makes interesting reading; in it, his own role is characteristically downplayed (Dyer, 1968). Arthur James Dyer was born in 1925. He eventually became a student at the University of Melbourne, after leaving an intimidating academic record behind him at Melbourne’s University High School. In 1946, Arch was awarded his B.Sc. degree in Physics, with First Class Honours. He went on to receive his M.Sc. degree in 1948, and a Ph.D. in Physics in 1953. Arch’s thesis was on the detection and measurement of cosmic rays. There was no meteorology in his curriculum, but immediately upon joining the Commonwealth Scientific and Industrial Research Organisation’s Meteorological Physics Section in 1954, he was rudely introduced to meteorology and especially to the technical limitations of meteorological sensing. At that time, the Section (later to become the Division of Meteorological Physics, then the Division of Atmospheric Physics, and now the Division of Atmospheric Research) was geared towards answering some specific questions about the dependence of surface fluxes on atmospheric and surface conditions. The team Arch joined was powerful, headed by C. H. B. (Bill) Priestley and W. C. (Bill) Swinbank, and with R. J. (Reg) Taylor, E. L. (Len) Deacon, I. C. (Ian) McIlroy, and E. K. (Eric) Webb forming the core of the experimental effort. Arch took over the responsibility for the electronics shop, which was then heavily involved in developments related to eddy correlation. It is worth remembering the times. Much earlier, Scrase (1930) had demonstrated that eddy correlation could be made to work, but had shown (with great emphasis) the difficulty of the job. In Australia, Swinbank, Priestley, Taylor, and Webb had explored the approach further, and had started intensive work on automating the analysis. The first computerized system employed a mechanical integration device, a ball-and-disc integrator in which one signal controls the speed of rotation of a disc and another controls the radius at which a tangential wheel contacts the disc (Taylor and Webb, 1955). The number of turns of the contacting wheel is directly related to the integral of