Published by the American Geophysical Union as part of the History of Geophysics Series, Volume 4.

It has been noted upon several occasions that the History of Geophysics volumes might do well to introduce to new generations of readers some of the early events of our organization, the American Geophysical Union, and of what may be considered to be its first journal, Terrestrial Magnetism (which later became the well-known Journal of Geophysical Research). Following the suggestions of my peers, this volume begins the practice of including some "early" articles, both about history of geophysics and about the history of AGU. For this volume I have selected materials taken from the founding of Terrestrial Magnetism in 1896 up to the beginnings of World War I. For example, Sir Edmond Halley's isogonic "Atlantic Chart" of 1701 sets Halley's cartographic work apart from all earlier extant charts and it is one of the "most important maps in the history of cartography. The Atlantic Chart was lost for over a century until it was rediscovered by L. A. Bauer and reproduced in the first issue of Terrestrial Magnetism. Halley's isogones he himself called "curve lines". They were generally known as "Halleyan" lines until Christopher Hansteen coined the term "isogone" about 1820. Other early articles I have chosen for reproduction here include biographical materials on Sir William Gilbert, and on Andrew Carnegie, the world's largest private benefactor of geomagnetism and geophysics, and articles on terrestrial magnetism and earthquakes. Much of these materials concern magnetism and were written or edited by L. A. Bauer. This is due partly to the nature of the early years of Bauer's journal and to Bauer's personal interests. It is hoped that future volumes of History of Geophysics will contain reproductions of historically significant articles representing additional disciplines in geophysics.