Page:Journal of the Asiatic Society of Bengal Vol 29.djvu/18

6 been the vent for fluid masses of rock, when such eruptions took place on a larger scale than in more recent times. The smaller cone in the centre of the old crater, corresponding in its size to the diminished forces of volcanic action, is of recent origin, and represents those smaller cones of still active volcanoes which are usually distinguished as cones of eruption from the original cones, also called the cones of elevation.

We have it on record that about 60 years ago, the crater of the little cone was throwing out showers of red hot stones of several tons weight and enormous volumes of smoke (Captain Blair's account Asiatic Researches 1795), and but for the island position of the volcano preventing its more frequent observation, we should doubtless be able to fix the date of the eruption that left the stream of lava behind, which is now filling the valley and its outlet into the sea. Since that time it has entered the period of decline of volcanic activity, without however leaving us the assurance that it will not some day revive again.

From barometrical observations, I deduced the height of the cone by Gauss's formula, allowing for the time of the day and the influence of the hot ground near the summit, to be about 980 feet, from the level of the sea to the northern edge of the crater. This height is confirmed by a trigonometrical measurement of Lieutenant Heathcote, I. N., to whom I am indebted for the communication of his results. He visited the Island about four months earlier than we did, when he found the height of the cone 975 feet above the level of the sea, and the diameter of the Island 2,970 yards, 1.69 miles North and South.

The few notes I could glean respecting the recent history of the Island, are derived from the Island itself, from the records of the Asiatic Society, and from Horsburgh. We found on a rock in the transverse valley the inscription "Galathea 1846", showing that since then no alteration has taken place. The same conclusion can be extended farther back to the year 1831 or 1832, judging from an account communicated to the Asiatic Society (Asiatic Society's Journal, April 1832) by Dr. J. Adam, whose informant landed in the month of March, and reached the base of the cone. By this explicit account, the descriptions of the Island "Lyell," dated 1843, and in