232 54 



From the measurements made on the 5th. August, it appears that the southern 

 geyser has four eruptions while the northern geyser has three, for ;$ x 147.5" 

 = 442.5" and 4 x 109.5" = 438". But this is probably quite fortuitous. 



p. Thoroddsen ' is of the opinion that these geysers had, in 1888, periods of 

 equal length, but my observations show that this is no longer the case. 



From what is known of the nature of the geysers, it is to be expected that 

 the weather has considerable influence on the periods of the springs. This is con- 

 firmed by people who live in the neighbourhood of the springs. They have noticed 

 that the eruptions of "Störi Geysir" especiallj' are greatly dependent on the weather. 

 In this connection I can also refer to tlie observations made by Gilbert Mair^, 

 showing that the weather has great influence on the thermal springs of New Zea- 

 land. The observations given above are an additional corroboration of change- 

 ability in the periods of the geysers, f(n- on the 5th. August the period of the 

 northern geyser was 147 seconds on the average, but on the 7th. it was about 222 

 seconds. This difference is remarkably great, especially when it is taken into 

 account that only 41 liours elapsed between the two observations. Several hot 

 springs in Yellowstone National Park' are found to have more than one distinct 

 range of periods. Nevertheless it seems to me hardly probable that the differences 

 I observed are due to such a cause, amongst other reasons because the transmis- 

 sion from one range of periods to another is usually attended by a change in the 

 energy of the eruption, whereas, as far as I could discern, the eruptions were 

 equally powerful at the time of both observations. 



There have been several theories advanced at diflerent times to explain the 

 activity of the geysers. A good idea of these so-called geyser theories can be formed 

 from Peale's treatise on "The Thermal Springs of Yellowstone National Park".* 

 A. Andreae' also mentions several geyser theories in his treatise on geyser models. 



The best known geyser theory is that of R. Bunsen". As this theory, in spite 

 of several serious objections to it, — that of H. O. Lang", for instance, — seems 

 still to be the geyser theory most generally recognised, it will be made the basis 

 of the following remarks concerning the phenomena. All the later geyser theories 

 are to some extent based on Bunsens theory and the materials acquired by his 

 observations. 



According to Bunsen'*, we must discern between hot springs with narrow 



' loc. cit. 



- New Zealand Trans. Inst. Î), pp. 22— 29, 1876. 



' Twelfth Annual Report of the U. S. Geological and Geographical Survey of the Territories. 

 Washington, 1883. Vol. II. 



' Twelfth Annual Report of the U. S. Geological and Geographical Survey of the Territories. 

 Washington, 1883; p. 417. 



'* Neues Jahrbuch der Mineralogi. 1893. Vol. II, p. 1. 



« Liebigs Ann. C2, 1. 1847. 



' Nachrichten v. d. Königl. Gesellsch. d. Wissenschaften zu Göttingen, 1880; p. 225. 



" loc. cit. p. 51). 



