Page:A Treatise on Geology, volume 2.djvu/233

 CHAP. IX. have been frequent, and almost regularly distributed, through the ten centuries during which it has been known to us. Dr. Daubeny notices as the first eruption recorded, that at the end of the ninth century (894 ). One also occurred in 900. The subsequent dates of eruptions are, 1000, 1004, 1029; 1104, 1113, 1157, 1158; 1245, 1262, 1294; 1300, 1311, 1332, 1340, 1359, 1374, 1390; 1416, 1436, 1475; 1510, 1554,1580, 1587; 1619, 1622, 1625, 1636, 1660, 1693; 1717, 1720, 1724, 1728, a series of eruptions, 1748 to 1752, 1753, 1772, 1783. In 1724 occurred the first eruption of Krabla. Eruptions have subsequently occurred in 1821, 1823.

During this period submarine eruptions happened from 1224 to 1240; in 1422; in 1563; 1783; and new islands were thrown up in 1563, 1783.

Here, therefore, we have the recorded history of four volcanic systems, which appear very unequal in their progress toward decay, as if their energy depended upon conditions differently apportioned to the several regions. Without repeating all the hypotheses in Ovid, which commence with the notion of the earth being an animal that breathes flame through many variable spiracles, we may inquire whether the fluctuation of volcanic energy in particular districts depends upon local and temporary stoppage of the channels to the surface, or upon the failure in some of the essential conditions of igneous excitement? To answer this