A Treatise on Magnetism, General and Terrestrial

Abstract

AN observational science like meteorology or terrestrial magnetism is placed in some respects at a disadvantage when compared with the more experimental branches of physical inquiry. It is often difficult to obtain a good and readable account of that which has been done. The reason of this is, that those who are personally engrossed with the science have to deal with such large masses of figures and precise measurements that they are frequently unable to spare the time necessary to give a good historical account of their favourite research. Those again who are the historians of science find it a very formidable task to bring themselves en rapport with all that has been done in such a subject as terrestrial magnetism—in fine, there is not sufficient inducement to undertake the task. No doubt, when such a science is more advanced and has attained a position like that of astronomy, it will find plenty of historians; but in its infancy, and when a good résumé of the progress already made is of peculiar value, it has comparatively few friends. Now these are precisely the circumstances when a Government or a University is able to interfere with very great effect, and with respect to terrestrial magnetism this opportunity has been admirably used by Trinity College, Dublin. The Rev. Dr. Lloyd tells us in his preface that the Dublin Magnetic Observatory was founded and placed under his superintendence by the governing body of Trinity College in 1838. This college has been peculiarly fortunate in having chosen as an observer the eminent physicist who is now its provost, and who, besides reaping much fame as a practical magne-tician, has at length found leisure to present us with the much-required treatise on terrestrial magnetism.