PROBABLY no country of Europe has had its geology more attentively studied and mapped than Belgium. From the early labours of the veteran and pioneer D'Omalius down to those of Dumont and his contemporaries, the structure of this country has engaged the attention of many able observers, and in its broad features is now well known. The map of Dumont, on the scale of 1-160,000, is one of the most excellent geological representations of any part of the European continent. But a good many years have passed away since its publication, and though it remains essentially accurate, it is now capable of improvement as regards details. Accordingly, after many discussions of the subject, a Commission was appointed to undertake a more detailed and exhaustive geological investigation of the country. This Commission consists of five members of European reputation, viz., M. Brialmont, Inspector-General of Engineers, one of the most distinguished engineer officers in Europe; M. Maus, Honorary Director-General of Bridges, Roads, and Mines, who made the preliminary plans for the piercing of the Mont Cenis Tunnel; M. Stas, the well-known chemist; M. Liagre, Perpetual Secretary of the Royal Academy of Belgium, who measured base-line of Belgium, and M. Houzeau, Director of the Royal-Observatory, whose writings on geological geography are widely appreciated. These able and thoroughly representative men of science were constituted as a Board of Control by which the operations of the Survey were to be governed, the practical carrying out of the work being placed in the hands of M. Dupont, Director of the Royal Museum of Brussels—a geologist of established reputation.