PREFACE.

The results of magnetic research on navigation, and the importance of a knowledge of the true direction of the compass and of the effect of the iron in a ship, are significant. But the labors of those who have endeavored to render navigation more secure by means of magnetic observations have, at the same time, greatly advanced the progress of pure science.

Gauss Carl Friedrich Gauss (1777–1855), a German mathematician and physicist who made fundamental contributions to magnetism., as a member of the German Magnetic Union, brought his powerful intellect to bear on the theory of magnetism and on the methods of observing it. He not only added greatly to our knowledge of the theory of attractions, but reconstructed the whole of magnetic science regarding the instruments used, the methods of observation, and the calculation of the results. Consequently, his memoirs on Terrestrial Magnetism original: Intensitas vis magneticae terrestris ad mensuram absolutam revocata (1832) may be taken as models of physical research by all those who are engaged in the measurement of any of the forces in nature.

The important applications of electromagnetism to telegraphy have also reacted on pure science by giving a commercial value to accurate electrical measurements, and by affording to electricians the use of apparatus on a scale which greatly transcends that of any ordinary laboratory. The consequences of this demand for electrical knowledge, and of these experimental opportunities for acquiring it, have been already very great. These factors have stimulated the energies of advanced electricians and diffused among practical men a degree of accurate knowledge which is likely to lead to the general scientific progress of the whole engineering profession.