CHAPTER IV THE DECADE 1850-1860. (By E. H. GROVE-HlLLS) THE period that we now enter upon is a profoundly interesting one, not only as considered from the view-point of astronomical progress, but as marking a fundamental change in the aspect and methods of all the physical sciences. It was indeed in a very real sense a transition period, when the old problems and the old modes of attack were either solved or exhausted, and when new questions, new and powerful instruments of research and new resources were being rapidly disclosed and developed. It will be hardly necessary to disclaim any intention of an attempt to write a history of the progress of astronomy during these ten years ; such would lie outside our scope, and space would not permit us to do it justice ; still less shall we venture upon an outline of the general progress of physical science during the period. It does, however, seem desirable, and in fact necessary, that before we enter upon our real theme, the history of the Royal Astronomical Society, we should pause for a few moments and try to picture to ourselves what actually was passing in the minds of scientific men at that middle of the nineteenth century ; that we should try, in a word, to catch the spirit of the time. Looking back from the vantage-point given us by the passage of seventy years, and standing therefore on an elevation which enables the veriest pigmy of to-day to overlook the head of the tallest giant aforetime, it is not difficult to seize this spirit and to see that this mid-century did in fact coincide with the epoch of a far-reaching change in scientific thought. This change was not, in the main, a change in the ideals or objects of scientific research ; it was shown rather in the direction of a fruitful development of new methods, often opening up entirely fresh vistas and giving access to territories before considered quite inaccessible. The de- velopment of spectrum analysis and its application to the heavenly bodies will sufficiently illustrate this point. In general physics, electricity and magnetism, light, thermodynamics, and the laws of energy and its transformations, this decade marked the end of the old experimental school and the rise of the new school of mathe- IIO
