Wind in Britain: The dines anemometer and some notable records during the last 40 years

In 1882 J. K. Laughton described in his address the development of anemometers up to that time. He mentioned three: Lind's, Wollaston's and Adie's‐elementary in character, but natural precursors of the Dines anemometer. This anemometer was developed by the late W. H. Dines in the succeeding ten years, and has reolutionized anemometry. The instrument utilises the difference between the pressure of the wind blowing on an open tube, and the suction caused by the wind blowing past holes around a vertical tube. This difference of pressure operates on a float which rises and falls as the strength of the wind changes. The float is shaped according to calculation (and not empirically) in such a way that the rise of the float is proportional to the velocity of the wind. The formula on which the calculation is based are worked out from first principles. A standard instrument of present‐day pattern is then described, and the refinements which have been introduced as the result of experience and modern knowledge of turbulent motion are explained. The methods adopted to prevent the instrument becoming choked with rime or snow, and to permit of its use on board ship, are also described. A brief history is given of the actual introduction of the instrument and its spread over the British Isles in the last 40 years. Records from the instrument are given, showing the effect of obstacles and of topography on the wind. For example: a wind of 25 m.p.h. over the tops of the buildings at S. Kensington oscillates between 5 and 45 m.p.h., while a wind of the same average strength blowing over the spit of sand known as Spurn Head, oscillates between 20 and 30 m.p.h.; the effect of a low building 25 feet away from the anemometer and 15 feet lower than the vane of the anemometer in its first position at the Lizard upset the records altogether, so that the wind went right round the compass and varied from calm to double its average speed. Further records show winds of special character like isolated squalls or winds rising and falling like regular waves at intervals varying from half‐an‐hour to five or six hours. A table is given showing the highest gust recorded in each year since 1909 at places equipped with the Dines anemometer, and the highest gust recorded at each place since the inception of the records. The actual records of the severest gales at a number of representative stations illustrate the varying ways in which the gales reach their climax, and show that the severest gales at most places come with winds between S. and W. and usually after a veer of two or three points of the compass. They also indicate that the highest gusts‐reaching in some cases 110 m.p.h.‐come usually in the afternoon or at night, and practically never in the forenoon. Finally it is suggested that, as the Dines anemometer gives a satisfactory visual record of the velocity and the direction of the wind but gives no information about the sound, which is a leading characteristic and the normal method of identification of the wind, an effort should be made to obtain satisfactory sound records as a natural complement to the satisfactory visual records of the Dines anemometer.