65 243 



velocity through the geyser channel, that it causes the water to rise in the shape 

 of a cone on the surface. These small eruptions are called "flöils" in Icelandic, 

 owing to the increase in the amount of water flowing away. These "flöös" are 

 subterranean eruptions, only much more powerful than similar eruptions in the 

 large hot water basins. The geyser channel, with its large funnel-shaped basin, 

 plays a similar part to the water basins in choking the eruptions. The circulation 

 of the water in the geyser channel is generally able to keep the temperature suffic- 

 iently low, so that the bubbles of steam condense on coming from the side chan- 

 nels. Occasionally, however, either on account of the subterranean eruptions being 

 more powerful, or because the loss of heat is less than usual, the steam bubbles 

 are able to fill up the whole width of the channel and raise the entire water 

 column, thus occasioning a large eruption. 



The pressure of the water column in the geyser channel is for the most part 

 suspended during the larger eruptions. The energy accumulated in the side chan- 

 nels has then more freedom to spend its strength than in the smaller eruptions 

 ("flöös"), where the subterranean forces have to work under the pressure of the 

 water in the channel. 



One can now understand that the period of inaction after a large eruption is 

 about twice as long as after a small one. ' For, after a long eruption, a far greater 

 supply of energy and spring gas must be conveyed to the side channels and their 

 cavities in order to enable them to produce a new eruption, than after a small one. 



At ÖskurhüU we noticed that the steam emissions varied in strength. We 

 could not make a closer investigation of the periodicity of the steam emissions, 

 but there is little doubt that ÖskurhöU must be reckoned amongst the periodic 

 springs. Small subterranean eruptions, either in the principal channel or, more 

 probably, in one of the side channels, would be sufficient to account for the 

 periodicity of the steam emissions. But it is nevertheless not impossible that 

 ÖskurhöU is in communication with one of the adjacent geysers, so that the varia- 

 tions in the steam emissions might be due to influences from another spring. 



Many attempts have been made to construct models to show in miniature 

 the mechanism of the geyser phenomena.' It seems to me, however, hardly pro- 

 bable that we can with these apparatuses make even an approach to the actual 

 conditions. In my opinion, the only thing which the geyser models have proved 

 with sufficient clearness, is that the relation of the width of the channel to the 

 steam evolution on the one hand, and the loss of heat in the channel on the otherj 

 is one of the chief causes of the intermittence or periodicity. But as to the part the 

 spring gases play in the eruption, very little information is to he gathered from 

 the geyser models. However, as stated, the relation between the spring gases and 

 the width of the channel is evidently the chief cause of the periodicity. 



1 Descloizeaux: Ann. d. Chem. 3rd. Series, 19, 456, 1847. 



' Full details of previous papers on Geyser Models are to be found in a paper by J. A. Andreae ,^*r 

 in "Neues Jahrbuch der Mineralogi", 1893, Vol. 11, p. 1. Manj- models are described in this paper. /^Js^ 



D. K. 1). Vidcnsk. Selsk. Skr.. 7. Hække, naturvidensk. og malhem. AW. VHI. 4. 32 



