On the laws of the tides on the coast of Ireland, as inferred from an extensive series of observations made in connexion with the Ordnance survey of Ireland

Abstract

The elaborate investigations of which the results are communi­cated in the present paper, were suggested by the necessity of adopting some standard mean height of the sea, as a line of refer­ence for the elevations ascertained in the operations of the Ordnance Survey of Ireland. Colonel Colby, R. E, who conducted that survey, had with this view determined to institute a series of observations on the height of the water in different states of the tide; and conceiving that these observations might be made subservient to im­provement in the theory of the tides, requested the assistance of the author in laying down the plan of observation best calculated to effect that object. The suggestions which were, in consequence, made by the author were adopted in their utmost extent by Colonel Colby; and the collection of observations was placed in the author’s hands in the winter of 1842. The whole number of observations exceeds two hundred thousand; and they derive extraordinary value from the circumstance of the localities, of their simultaneity, their extensive range, and the uniformity of plan on which they were con­ducted. Their reduction was made by the computers at the Royal Observatory, Greenwich, under the superintendence of the author, and with the authority of the Lords Commissioners of the Treasury. The nature of the different branches of the inquiry may be gathered from the titles of the several sections into which the paper is divided, and which are as follows :— Section I.—Account of the stations, levellings, times and methods of observation.