212 Jaggar — Yolcanologic Investigations at Kilauea. 



than that of tlie Seger cones, is still much lower than was ex- 

 pected. And probably the Seger cones afford the more 

 reliable data. The writer recalls assisting Dr. Dalj in 1909 in 

 some temperature readings on i\\Q fountains of Halemaumau, 

 made with Ferj pyrometer, when a temperature of 940° C. 

 was registered, and this was believed at the time to be much 

 too low. In general these first experiments of 1917 show that 

 the lake magma is much cooler than has been supposed. 



Temperatures of Grottoes and Flames. , 



The next temperature tests with Seger cones January 18, 

 *22 and 26, 1917, were devised with a view to determining the 

 relative heat of the lake magma twenty feet (6"") from a grotto, 

 of the lava inside a grotto, and of the burning gas from a 

 blowing cone. Supposing that possibly the three-inch (S"^"") 

 cylinder of the first experiments made too large an air space 

 around the Seger cones, and also because such a cylinder „ was 

 awkward for recovery when it became clogged with crusts, a 

 simpler device was nsed for holding the cones. The six Seger 

 cones were placed end to end in a spiral of steel wire nineteen 

 inches (IS'^'") long and this was inserted directly in the end of 

 the one-inch pipe which Avas closed with a screw cap. The 

 upper end of the pipe was open. From the results of this 

 second series of experiments, which for the lake lava showed 

 the same tendency to low temperatures, but elsewhere fused 

 the Seger cones abundantly, the writer is convinced that the 

 air space in the larger pipes somewhat invalidated their results. 

 The following are the records of the second series (fig. 19) : 



Jan. 18— First Test. Six Seger cones of fusibilities 590° C. to 

 1070° C.,. heated close to lake surface 30 minutes, then 

 dipped under lava one minute. Dipping was not complete, 

 so that three upper Seger cones of low fusibilities were less 

 blackened than the three lower ones. The three lower 

 cones which were blackened were of fusibilities 870° to 

 970° C. Only the cone of 870° fusibility showed any 

 fusion effect and this was very slight on the angular edges 

 of the cone. As the pipe became involved in crust and 

 the zinc galvanizing of its outer surface burned with a 

 bright greenish yellow flame, it is possible that this fusion 

 of cone 870° was induced by an artificial reaction. 



Jan. 18 — Second Test. Repetition of first test, six Seger cones 

 of fusibilities 590° to 1070 C. heated 30 minutes close to 

 lake surface, then dipped completely for one minute so 

 that all the cones were immersed in the lake. Again the 

 pipe was entangled in crusts, bent and recovered with 

 great difficulty. All of the cones were blackened, but 

 none of them was fused, not even that of fusibility 590° . 



Jan. 22— Six Seger cones of fusibilities 590° C. to 107o° C. in 

 the end of a pipe 40 feet (12™) long were placed in the 



