ANNIVERSARY ADDRESS OF THE PRESIDENT. liii 



There are two obvious conjectures as to their origin : the one is, 

 that surface waters may percolate deep into the earth and penetrate 

 to the volcanic focus, and we know from the celebrated case in South 

 America mentioned by Humboldt, that large masses of subterranean 

 fresh water have been brought within the reach of volcanic force ; 

 and the mud, or Moya, which was thrown up from the interior of 

 the earth during the earthquake of Riobamba in 1797? contained 

 siliceous shells of infusoria. The other conjecture is, that old sedi- 

 mentary beds, containing infusorial remains, lying within the reach 

 of the volcanic force, may have been shivered to atoms, and blown 

 out at the orifice. We know that the shells of species of infusoria 

 that cannot be distinguished from those now living have been found 

 in sedimentary deposits of very old date ; and Ehrenberg informs 

 us that infusorial remains have been found in beds of the coal- 

 formation near Dresden. 



M. Flourens communicated to the Academy of Sciences on the 

 16th of November the results of some observations of MM. Des- 

 cloizeaux and Bunsen last July, on the intermittent boiling springs of 

 the Geyser and Strockr* ,i\iQ latter being within 140 yards of the Great 

 Geyserf . The observations were on the temperature of the water, 

 in the great column or well of each, made by suspending thermo- 

 meters at different depths, at different times before and after erup- 

 tions. The Great Geyser has a depth of 22 metres (72 feet), and 

 the experiments showed that the temperature of the column dimi- 

 nished gradually from the bottom upwards, and that the maximum 

 temperature at the bottom before a great eruption was 127°*6 Centi- 

 grade (260°i Fahr.), and the minimum 122° (251 °J Fahr.) after an 

 eruption. The temperature of the water at the surface was 85°'2 

 (185° Fahr.), when that at the bottom was 127°. 



After an eruption, the lowest thermometer stood at 121°-6 (251° 

 Fahr.); nine hours afterwards at 123°-6 (254 j° Fahr.). Between 

 11 o'clock A.M. of the 6th July and 2*55 p.m. of the 7 th, there 

 was no eruption, so that there had been an interval of nearly twenty- 

 eight hours ; and the water at the latter time, at the bottom, was 

 127°*6 (26 1^° Fahr.) ; a quarter of an hour afterwards there was a 

 slight eruption. 



The Strockr is a circular well 44^ feet deep, with an orifice of 

 about 8 feet which rapidly diminishes downwards, and at about 27J 

 feet from the surface the orifice is only \0^ inches. The column of 

 water between the eruptions has a mean depth of 272- ^^^^' ^^ *^^^ 

 its surface, which is in a constant state of ebullition, is generally from 

 10 to 13 feet below the surface of the ground. The temperature of 

 the water at the bottom varied from 112°-9 to 114°-2 (235° to2374° 

 Fahr.), and the same temperature continued throughout a depth of 

 about 20 feet, when it began to sink, and at the surface of the 

 water the thermometer stood at 100° (212° Fahr.). 



* It is called Strokkus in the Comptes Rendus, but Henderson calls it Strockr, 

 and says the name is derived from the verb " strocka," to agitate, or bring into 

 motion. 



f Henderson's Iceland, page 69. 



e2 



