Note 1 — APPENDIX. A BRIEF ACCOUNT OF THE PRINCIPAL VARIETIES OF VOLCANIC ROCKS.
Reading edition
Mr. S. Allport has discovered this in the rock called the "Wolf Rock" off the coast of Cornwall. The most important work on basalt is that by F. Zirkel, Unters. über mikros. Zusammensetzung und Structur der Basaltgesteine. Bonn (1870).