and 1805 is almost as striking as that of those taken from 1816 to 1822. In the latter period we cannot doubt the height being from about 621 to 629 toises (3970 to 4022 English feet). Are the measurements made from thirty to forty years earlier, which gave only 606 to 609 toises (3875 to 3894 English feet), less certain? At some future day, after longer periods shall have elapsed, it will be possible to decide what is due to errors of measurement, and what to an actual rise in the margin of the crater. There cannot be in this case any accumulation of loose materials from above. If the solid trachyte-like lava beds of the Rocca del Palo really become higher, we must assume them to be upheaved from below by volcanic forces.
My learned and indefatigable friend Oltmanns has placed all the details of the above measurements before the public, accompanied by a careful critical examination of them, in the Abhandl. der königl. Akademie der Wissenschaften zu Berlin, 1822-1823, S. 3-20. May this investigation be the means of inducing geologists frequently to examine hypsometrically this low and most easily accessible (except Stromboli) of the European volcanos, so that in the course of centuries there may be obtained a frequently checked and accurate account of its periods of development!Compare Leopold von Buch on the Peak of Teneriffe in his Physikalische Beschreibung der canarischen Inseln, 1825, S. 213; and in the Abhandlungen der königl. Akademie zu Berlin, 1820-1821, S. 99.
