The lead mines described in this Memoir have been extraordinarily productive, and it is by no means certain that large deposits may not yet be discovered in the area.

Preface by the Director.

The area with which this Memoir deals includes portions of the One-Inch Sheets 163, 164, 178, 179.

Preface by the Author.

From the mouth of the river Dovey to Machynlleth the limit of the area coloured on the map accompanying the memoir is the county boundary between Montgomery and Merioneth : thence to Caersws the Cambrian Railway forms a convenient limit, while south of this point one may regard the geological line formed by the base of the Wenlock formation as the extreme eastward limit of ore-occurrence within the area.

Chapter I. - Introduction.