400 



jaggar: thermal gradient at kilauea 



ternal diameter, containing Seger cones with their tips held free 

 in air, failed to transmit the full temperature of the melt to the 

 cones, owing probably to circulation of the air and consequent 

 heat insulation for the limited time of exposure (five to eleven 

 minutes). In later tests with 12-mm. pipes the results were 

 accordant with tests in glowing caverns where the Seger cones are 

 exposed directly, and with the observed incandescence. Ac- 

 cordingly where a large pipe is used to contain a removable series 

 of batteries of cones exposed all at once, the relative tempera- 

 tures are measured, but the figures are too low N by an error ap- 

 proximately constant. A and B of the diagram show respec- 



TABLE 1 



Group 1. Upper Temperature (triangles) 



TEMPERATURE (SE- 

 GER CONE EFFECT) 



Fusibility 990 c 

 unaffected 



Fusibility 770° 

 unaffected 



Fusibility 870° 

 slightly af- 

 fected 



Fusibility 590° 

 unaffected 



Fusibility 1070° 

 unaffected 



1070° fused 



CONDITIONS 



Special steel container for 6 

 Seger cones in steel cyl- 

 inder 7.6 cm. internal 

 diameter attached to steel 

 pipe 2.5 cm. internal diam- 

 eter. Pipe bent sharply 

 at lava surface, straight 

 above and beloio 



Cylinder 7.6 cm. Compare 

 April 5 



Steel pipe 2.5 cm. internal 

 diameter, heated first in 

 air 30 cm. above lake 30 

 minutes. Seger cones in 

 spiral of spring steel in 

 sealed end of pipe. Trou- 

 ble with moving crusts 



2.5-cm. pipe, heated first in 

 air 27 minutes, much crust 

 trouble 



2.5-cm. pipe, heated first in 

 air 27 minutes, much crust 

 trouble 



2.5-cm. pipe, heated first in 

 air over fountaining grotto 

 lOminutes, then submerged 

 in boiling grotto-lava 



