It was _Leverrier_ (died 1877), Director of the Paris Observatory, who by calculations ascertained the existence and exact position of the remotest planet Neptune even before it was discovered. When eventually _Galle_ of Berlin really found the planet in the position indicated, _Leverrier’s_ name became famous. But greater still were the achievements of this indefatigable investigator in respect to the known planets. When he presented to the French Academy the final part of his great work, the calculations of Jupiter and Saturnus, he said: “During our long labours, which it took us thirty-five years to complete, we needed the support obtained by the contemplation of one of the grandest works of creation, and by the thought that it strengthened in us the imperishable truths of a spiritualistic (_i.e._, non-materialistic) philosophy.” He was an orthodox Catholic, known as a Clerical. A newspaper complained of him that “Under the empire he was a clerical Senator, concerned with the interests of the altar no less than with those of the throne” (_Kneller_, Das Christenthum und die Vertreter der neueren Naturwissenschaft, 1904, 96. In the following pages we have made frequent use of the material gathered in this sterling work. See also _James J. Walsh_, Makers of Modern Medicine (1907); and the same author’s Catholic Churchmen in Science, I (1909), II (1910)). One year after the death of _Leverrier_ another scientist of the first rank died. It was _A. Secchi_ (died 1878). Member of nearly all the scientific academies of the world, he was not only a faithful Christian, but also a priest: for forty-five years, and until his death, he wore the garb of the Society of Jesus. As an astronomer he has been named, not without good cause, the father of astrophysics: he ascertained the chemical composition of about 4,000 stars and classified them into what is known as _Secchi’s_ four types of stars. As a physicist he wrote an important work on The Unity of Natural Forces. He was also an eminent meteorologist.