The paper describes an investigation in which the dynamic response of a vertical cantilever structure exposed to the natural turbulent wind was observed. The structure consisted of a steel tube 2 743 m (9 ft) high on the top of which was mounted a closed drum 609 6 mm (2 ft) diameter by 609 6 mm (2 ft) high. The deflexions of the drum on two orthogonal axes were measured and also the strains near the lower end of the steel tube. Wind velocity was measured with a hot–wire anemometer and all the measurements were recorded on a high speed ultraviolet recording galvanometer. The results are considered in two parts: (a) the response transverse to the wind direction (b) the response in the direction of the wind. The transverse displacements are accounted for by vortex shedding and the longitudinal displacements can be calculated from the wind velocity trace, given the requisite structural parameters. Many engineering structures can be considered as structures of one degree of freedom and it appears that the behaviour of all such structures can be predicted by the method used in this investigatio