210 Jaggar — Yolcanologic Investigations at Kilauea. 



sary to wait for a rending of the crusts, wliich revealed the 

 yiscoiis glowing slag beneath, or to find a place, otherwise con- 

 venient, where one of tlie ragged glow lines of iipwelling was 

 maintained (fig. lid and 20). It was necessary, moreover, for 



Fig. 20. 



Fig. 20. Jan. 31, 1917, 6 p. m. Depression 4« ft. (15 m.). Looking N.W. 

 Violent fountaining, blowing, flaming and overspatter in grotto under S.E. 

 rampart. Shortly after time of PI. 16 ; when quiet overflow had ceased and 

 depression had begun. Note trajectory of flying spray, in the midst of 

 which were great banners of flame. Wide gloTv lines under S. island in con- 

 trast to PI. 16 : indicates incandescent overhang at lake margin due to 

 temporary subsidence. This glow rim appears all around lake. General 

 subsidence and fountaining follow intervals of quiet inflation. Photo 

 Morihiro. 



such a liquid place to persist for some minutes, in order to 

 leave the pipe submerged long enough to insure thorough heat- 

 ing of the Seger cones within, and then it was problematical as 

 to whether the pipe could be withdrawn, as heavy crusts were 

 apt to pile against it and to freeze around it. It commonly 

 took the united strength of four or five men to withdraw a 

 jDipe (fig. ITc), and on two occasions the pipe was lost. For- 

 tunately the surface current proved shallow and while the 

 heated pipe always bent during immersion, it was commonly 

 held by border crust at the lake surface, so as to prevent its 

 being swept along. 



