24

officers, both public and private; and it was only through the opportunities thus afforded that I was enabled to gather the necessary information.

I am under special obligations for assistance and courtesies to Dr. Hauchecorne, Director of the Geological Survey of Germany, and to other members of the survey; to Frhr von der Heyden-Rynsch, Imperial Director of Mines of the District of Halle a. S.; Dr. Brassert, Imperial Director of Mines of the District of Bonn; Prof. H. Credner, University of Leipzig; Prof. Frech, University of Halle; Prof. Laube, German University of Prague; Eng. E. Preissig, Prague; Dr. Geinitz, Director of the Royal Mineralogical Museum, Dresden; Profs. Toula, Oser and Hofrath von Hauffe, Institute of Technology, Vienna; Profs. Höfer and Kupelwieser, Mining Academy, Leoben; Alex. von Napolski, Halle a. S.; the officers of the A. Riebecksche Montan-Aktién-Gesellschaft, Halle a. S.; Oesterreichisch-Alpine Montangesellschaft; Teplitzer Walzwerk und Bessemerhiitte; Wiener Locomotivs-Fabrik; Zeitzer Eisengiesserie und Maschinenbau Aktién-Gesellschaft; and above all to Prof. Freiherr von Fritsch, of the University of Halle.