_Hekla_ is the greatest volcano in Iceland and in some respects the greatest in the world. What makes a volcano great? Is it the area of the base and its altitude? Is it the number of recorded eruptions? Is it the number of people it has destroyed together with their flocks and herds? Is it the space of territory devastated and the duration of any one or any series of its eruptions? This volcano was doubtless active prior to the settlement of the country as shown by the formation of its slopes, but since 1004 there have been twenty-five recorded eruptions, each of a serious nature to the country and destructive of life and property. Some of these eruptions have lasted only a few days and several for months and the one beginning in 1766 lasted two years. The great eruption was in 1845 and lasted seven months. The shortest period between eruptions was from 1294 to 1300, only six years, and previous to this eruption the volcano had been quiet for seventy-two years. The longest period was between the last two eruptions, 1768 to 1845, seventy-seven years and this followed the long eruption of two years. The average period of inactivity from 1004 to 1845 is thirty-two years. These figures do not take into account the frequent flowing of lava from the rifts during the periods of so-called inactivity. The following are the most memorable eruptions,— [5]1294 Eighth recorded eruption. There were violent and destructive earthquakes throughout the country. Great rifts in the old lava plains were opened. The rivers were covered with pumice and many of them changed their courses. New hot springs came into existence and others disappeared. There was great destruction of life and property. 1300 Ninth recorded eruption and following the short period of six years of rest. This was one of the most violent on record. Ashes covered hundreds of miles of the north country. There were many severe earthquakes and the destruction of the grass and livestock produced a famine with resulting heavy loss of life. 1436 Thirteenth recorded eruption. Many homesteads and much arable land laid waste under a mantle of scorching ashes. 1510 Fifteenth recorded eruption. Enormous volumes of ash and pumice were poured out and myriads of lava bombs were scattered for miles, which in falling demolished houses and killed livestock and people. 1583 Sixteenth recorded eruption. This was excessive in its violence. Thundering explosions were audible throughout the island and continued for twelve days with great violence. Eighteen columns of flaming gases issued from as many different vents in the mountain. Earthquakes destroyed many farms and hundreds of the turf and stone dwellings were demolished. There was a great loss of life.