The present year of 1918 finds the world at large, and with it the world of science, painfully crushed beneath the overwhelming weight of a world war of unprecedented severity. The four terrible years now nearly finished have seen a fearful destruction of life and property which must have a sad influence on the progress of science for many years to come. Only in certain restricted lines has there been a partial compensation in the stimulating influence due to the immediate necessities connected with the great conflict. One hundred years ago “the reign of war” was keenly in the mind of the editor in beginning his work, but for him, happily, the long period of the Napoleonic wars was already in the past, as also the brief conflict of 1812, in which this country was engaged and in which Silliman himself played a minor part. We, too, must believe, no matter how serious the outlook of the present moment, that a fundamental change will come in the not distant future; the nations of the world must sooner or later turn once more to peaceful pursuits and the scientific men of different races must become again not enemies but brothers engaged in the common cause of uplifting human life. The peace that we look forward to to-day is not for this country alone, but a peace which shall be a permanent blessing to the entire world for ages to come. NOTE.—The portrait which forms the frontispiece of this volume has been reproduced from the plate in volume =50= (1847). The original painting was made by H. Willard in 1835, when Silliman was in Boston engaged in delivering the Lowell lectures; he was then nearly fifty-six years of age. The engraving, as he states elsewhere, was made from this painting for the Yale Literary Magazine, and was published in the number for December, 1839. It is interesting to quote the remarks with which the editor introduces the portrait (=50=, xviii, 1847). He says: The portrait prefixed to this volume was engraved for a very different purpose and for others than the patrons of this Journal. It has been suggested by friends, whose judgment we are accustomed to respect, that it ought to find a place here, since it is regarded as an authentic, although, perhaps, a rather austere resemblance. In yielding to this suggestion, it may be sufficient to quote the sentiment of Cowper on a similar occasion, who remarked—“that after a man has, for many years, turned his mind _inside out_ before the world, it is only affectation to attempt to hide his face.” _Notes._ Footnote 1: