AUTHOR’S PREFACE. 1 he uninterrupted geognostic observations in which I have been engaged, have been prin cipally directed to a consideration of the differ ent mineral repositories ; and, with the view of rendering my remarks more useful and appli cable to the practical operations of mining, my attention has been directed to every circum stance which could make me acquainted with the nature and peculiarities of each of these, but more particularly of veins, which, being of great variety, and having undergone many changes, are of a very complicated nature. In studying veins, I have not only applied myself to discover, as much as possible, their nature and properties, as well as their different rela tions to one another, and to the substance of the rocks in which they occur, but I have also endeavoured