One of the craters deserves a special description. It is shaped like an inverted funnel with the stem cut off at the apex of the funnel. Out of this orifice the lava was hurled in liquid drops to so great a height in the air that it cooled and the bombs returned to the crater and around it like a shower of grape-shot. It must have been a wonderful sight, the spraying of the upper air with liquid lava like water from a hose and to such an altitude that the stream broke into drops and every drop cooled before it returned to earth. A few of the bombs are fused together because they collided in a viscid condition. Others are flattened because the mass struck the earth before they had become rigid; but most of them are spherical and vary in size from tiny pellets to a croquet ball. There are several _tintrons_ around _Mývatn_ and in the adjacent region of _Húsavik_. A _tintron_ is a hornito, or more correctly speaking, a lava chimney. A hornito is a veritable lava oven from which issues smoke and fumes and it may be level or even sunk below the level of the general surface of the lava sheet; while a _tintron_, like a factory chimney with a spreading base, rises from the level ground to the height of many feet. It is evident from examination that they were formed by the spouting of lava in a liquid state so hot as to have lost its viscousness, and, like geyser-formations, that which fell upon the rim cooled and continual spoutings built the _tintron_. We ascended one of the _tintrons_ beside the lake and gazed down into its black depths. The outer surface at the base is clothed with grass while the _tintron_ proper is encrusted with lichens. What a rugged and forbidding aspect is presented in the interior! Deep, deep down into the earth extends the flue, its wall hung with lava stalactites and patches of lava that solidified as the material dripped back into the interior after an explosion. Of the scores of craters around _Mývatn_ that I explored, only one contained water,—except those in the lake,—and this one is known as _Thangbrandspollr_, _Thangbrand’s_ Pool. _Thangbrand_ was a Saxon Priest whom Olaf Tryggvason, King of Norway (995-1000 A. D.) sent to Iceland to perform a wholesale christening of the pagans. King _Olaf_ forced Christianity upon his subjects at the point of the sword, killing and plundering all who refused to forsake the worship of _Thor_ and _Odin_ and take the christening. _Thangbrand_ was chosen for the Icelandic mission because of his inhuman and zealous methods. He had, what he deserved, little success. We read that,— [9]“Hall let himself be christened and all his household.” It was merely the act without any conversion from Scandinavian polytheism. Again we read,— “Winterlid, the Scald, made a scurvy rime about him,” _Thangbrand_. And again we find,—