LIGHT-DUTY • DICCIONARIO INGLES.COM • Definition of Light-duty

... commissioners to purchase the light duties and the Island of May, for the sum of sixty thousand pounds. This was accordingly done, and on the completion of the purchase, the first act of the commissioners was to reduce the light-duty to all British vessels, so that English and Irish ships were no longer treated as foreigners, by paying double duty. Immediate measures were also taken for altering and improving the light; a new lighthouse was erected, and a light from oil, with reflectors, was exhibited ...

— Smeaton and Lighthouses - A Popular Biography, with an Historical Introduction and Sequel • John Smeaton