square feet. In the De Beers Mine is what is called " the snake," a dyke of igneous rock taking a serpentine course across the mine, and standing like a vein nearly vertical, varying in thickness from 2 to 7 feet. The main body of the blue ground is entirely analogous to the snake rock, naturally more decomposed, but in essential points the microscopic appearance of the blue ground and of the "snake " is in an extraordinary degree alike. Mr. Gardner Williams supposes that the " snake " is a younger eruptive formation coming from the same volcanic source as the blue ground. No diamonds have been found either in the " snake " or the floating reef. The ground, however, is generally richer in diamonds in the neighbourhood of the floating reef.
Before the discovery of the mines there was nothing in the superficial appearance of the ground to indicate the treasures below. Since the volcanic ducts were filled with
