In his last statement, 1818, he admitted that to his telescopes the Milky Way had proved fathomless, but on "either side of this assemblage of stars, presumably in ceaseless motion round their common center of gravity, Herschel discovered a canopy of discrete nebulous masses, such as those from the condensation of which he supposed the whole stellar universe to be formed."
In the theory of the evolution of the heavenly bodies, as set forth by Kant, Laplace, and Herschel, it was assumed that the elements that composed the earth are also to be found elsewhere throughout the solar system and the universe. The validity of this assumption was finally established by spectrum analysis. But this vindication was in part anticipated, at the beginning of the nineteenth century, by the analysis of meteorites. In these were found large quantities of iron, considerable percentages of nickel, as well as cobalt, copper, silicon, phosphorus, carbon, magnesium, zinc, and manganese.
G. F. Becker, Kant as a Natural Philosopher, _American Journal of Science_, vol. V (1898), pp. 97-112.
Agnes M. Clerke, _History of Astronomy during the Nineteenth Century_.
Agnes M. Clerke, _The Herschels and Modern Astronomy_.
Sir William Herschel, Papers on the Construction of the Heavens (_Philosophical Transactions_, 1784, 1811, etc.).
A. R. Hinks, _Astronomy_ (Home University Library).
E. W. Maunders, _The Science of the Stars_ (The People's Books).
In the middle of the eighteenth century, when Lambert and Kant were recognizing system and design in the heavens, little progress had been made toward discovering the constitution of matter or revealing the laws of the hidden motions of things. Boyle had, indeed, made a beginning, not only by his study of the elasticity of the air, but by his distinction of the elements and compounds and his definition of chemistry as the science of the composition of substances. How little had been accomplished, however, is evident from the fact that in 1750 the so-called elements--earth, air, fire, water--which Bacon had marked for examination in 1620, were still unanalyzed, and that no advance had been made beyond his conception of the nature of heat, the majority, indeed, of the learned world holding that heat is a substance (variously identified with sulphur, carbon, or hydrogen) rather than a mode of motion.