57 235 



From this diagram it is evident that the temperature measurements of the 

 two experiments omitted by Blnsen are in fair agreement with the other measure- 

 ments. Two measurements in the first experiment, however, seem to be a good 

 deal too high, but botli these measurements are given with a mark of interrogation, 

 and may therefore be regarded as uncertain. A glance at the diagram also shows 

 that the measurements of the second experiment, (line 4 in Bunsens paper), does 

 not agree with the other measurements. This would lead one to suppose that an 

 inaccuracy has crept into this experiment. This suspicion is strengthened by the 

 fact that if these measurements are correct, the temperature of the water must 

 have risen about 2° C. from 19.2 m. to 14.4 m., and 17° C. from 14.4 m. to 9.6 m., 

 which seems in the highest degree improbable. Such abnormities are not to be 

 found in the other experiments. This disagreement is readily explained by sup- 

 posing that the thermometer measuring the temperature at 14.4 m. remained higher 

 up the channel, at about 17.8 m., and as all the thermometers were hanging on the 

 same string, the result would be that the thermometers which were farther down 

 the channel measured the temperature 3.4 m. higher up than was assumed by 

 BuNSEN and Descloizeaux. The dotted line, constructed on the basis of this sup- 

 position, now shows a fair consistence to the other lines. But the lines in this 

 instance have a vastly different significance to that which Bunsen assigned to them. 

 In the first place, we observe that the lines form a well-marked angle at about 9 m. 

 In this respect they resemble the temperature curves of Strokkur'. The significance 

 of this is evident enough. The heat supply is brought into the geyser channel in the 

 neighbourhood of the spot corresponding to the angle in the temperature curve, 

 i. e. about 9 m. from the bottom. Thus the temperature measurements are brought 

 into harmony with direct observations by Bryson-. He has found that at a depth 

 of 45 feet from the surface, there is a projecting rim in the geyser channel, and 

 that very hot water and steam flow into the channel immediately beneath this rim. 

 As it is known that Strokkur also has side channels, the manner in which the 

 temperature in the channel of this spring varies with the depth must naturally be 

 explained in the same way. Bunsen's supposition that the lower part of Strokkur's 

 channel must be full of steam, is therefore incorrect. It must be filled, as in the 

 case of "Störi Geysir", with stagnant or almost stagnant hot water. 



Bunsen reports several peculiarities in the eruptions of "Störi Geysir", which 

 in his opinion indicate the existence of fissures in the sides of the geyser channel 

 supplying the channel with hot water and steam during the eruptions. But he 

 considers this to be of secondary importance. But it is, however, of great importance 

 in considering Bunsen's objections against Mackenzie's theory. Bunsen proved, by 

 actual experiment, that a thermograph could lie unmoved and unharmed at the 

 bottom of the channel during an eruption of "Störi Geysir". This, he contended, 



' Liebigs Ann. 62, 39, 1847. 



- Frost and Fii-e. Vol. II, p. 417. 



U. K. I). ViiLensU. Selsli. SUr., 7. Rielike, nalurvldensk. ok mallicni. Afd. VIII. 4. 31 



