Tables of difference of latitude and departure for navigators : Land Surveyors, &c. with their application to plane trigonometry, And their Use in plotting and calculating surveys, Which perfects the House-Work of that Art. To which is prefixed, An Account of the Diurnal Variation of the Magnetic Needle, the Error thence arising and its Correction; the Use of a new Surveying Instrument, &c. Being great Improvements of the Field-Work. The Whole almost Entirely New. Compiled at the Instance of a Committee of the Dublin Society, By John Hood, Land Surveyor