The paper now offered to the Society forms the XVth and last of a series of papers printed in the Philosophical Transactions, entitled “Contributions to Terrestrial Magnetism.” The whole Fifteen. Numbers are related to each other as “Contributions to the Magnetic Survey of the Globe.” Four of them (viz. XI., XIII., XIV., and the present paper) contain the complete statement of this Survey in the double form of “Catalogue” or “Tables” and of “Magnetic Maps; ” of these maps there are twelve,one for each of the three magnetic elements in each of the four papers. The present paper consists (as did its last predecessor, No. XIV.) of four zones, each 10° in breadth:— Zone 1, comprehending from the equator to 10° S. Zone 2, „ „ lat. 10° S. „ 20° S. Zone 3, „ „ lat. 20° S. „ 30° S. Zone 2, „ „ lat. 30° S. „ 40° S. In the Tables the observations are entered in each zone in the succession of their longitudes, beginning with the meridian of Greenwich. The statements in the introduction to No. XIII. regarding the different magnetic elements apply to the present paper, as they did also to the preceding paper (No. XIV.).