ne difficult to separate vegetable and animal remains from each other. The same mode of explanation ought to comprehend both. I have permitted myself at the conclusion of the present discussion to connect with facts collected in different and widely separated countries some uncertain and hypothetical conjectures. The philosophical study of Nature rises beyond the requirements of a simple description of Nature: it does not consist in a sterile accumulation of isolated facts. It may sometimes be permitted to the active and curious mind of man to stretch forward from the present to the still obscure future; to divine that which cannot yet be clearly known ; and thus to take pleasure in the ancient myths of geology reproduced in our own days in new and varied forms. ANNOTATIONS AND ADDITIONS. (1) p. 226.-" A more complete determination of the height of all parts of the margin of the crater." Oltmanns, my astronomical fellow labourer, of whom, alas! science has been early deprived, re-calculated the barometric measurements of Vesuvius referred to in the preceding memoir (of the 22d and 25th of November and of the 1st of December, 1822), and has compared the results with the measurements which have been communicated to me in manuscript by Lord Minto, Visconti, Monticelli, Brioschi, and Poulett Scrope. A. Rocca del Palo, the highest and northern margin of the Crater Breislak, 1794, barometric (but, like Poli, the for mula employed uncertain). Gay-Lussac, Leopold von Buch, and Humboldt, 1805, barometric, computed by Laplace's formula, as are also all the barometric results which follow. Brioschi, 1810, trigonometric Visconti, 1816, trigonometric Lord Minto, 1822, barometric, often repeated Poulett Scrope, 1822, barometric, somewhat uncertain from the proportion between the diameters of the tube and cistern being unknown Monticelli and Covelli, 1822. Humboldt, 1822. Most probable result 317 toises, or 2027 English feet, above the Hermitage; or 625 toises, or 3996 English feet, above the level of the sea. B. The lowest and southern margin of the crater opposite to Bosche Tre Case. After the eruption of 1794 this edge became 400 Toises. Eng. ft. (426 Eng.) feet lower than the Rocca del Palo; therefore if we estimate the latter at 625 toises (3996 English feet). 559 3574 Gay-Lussac, Leopold von Buch, and Humboldt, 1805, barometric C. Height of the cone of scoriæ inside the crater, which fell in on Probable final result for the height of the above-mentioned cone of scoriæ 646 toises, or 4130 English feet. D. Punta Nasone, highest summit of the Somma. E. Plain of the Atrio del Cavallo. Humboldt, 1822, barometric F. Foot of the cone of ashes. Gay-Lussac, Leopold von Buch, and Humboldt, Gay-Lussac, Leopold von Buch, and Humboldt, 1805, barometric Lord Minto, 1822, barometric Humboldt, 1822, barometric repeated. 1969 1974 Part of my measurements have been printed in Monticelli's Storia de' fenomeni del Vesuvio, avvenuti negli anni 18211823, p. 115; but the neglected correction for the height of the mercury in the cistern has somewhat disfigured the results as there published. When it is remembered that the results given in the above table were obtained with barometers of very different constructions, at various hours of the day, with winds from very different quarters, and on the unequally heated declivity of a volcano, in a locality in which the decrease of atmospheric temperature differs greatly from that which is supposed in our barometric formulæ, the agreement will be found to be as great as could be expected, and quite satisfactory. My measurements in 1822, at the time of the Congress of Verona, when I accompanied the late King of Prussia to |