Jaggav— Yolcanologlc Investigations at Kilaiiea. 211 



Temperature of Lava Lake. 



The first three tests with Seger cones were directed to deter- 

 mining the temperature of the liquid lava just beneath the 

 surface crusts, with immersion of about three feet (one meter) 

 of pipe. Six Seger cones were used in each test, of fusibilities 

 differing progressively by about 40° C. The following were 

 the results of these three tests (fig, 19) : 



Jan. 11 — Six Seger cones of fusibilities 990° C. to 1150° C, im- 

 mersed 6 minutes, 3 feet (1"^) below crust of lake; cones 

 blackened but no trace of fusion (fig. lib). Highest glow 

 and sharpest bending of steel pipe were at point of immer- 

 sion, where gas burned in air, showing zinc flame coloration 

 from galvanizing on pipe. 



Jan. 15 — Six Seger cones of fusibilities 770° C. to 990° C, im- 

 mersed 11 minutes, 3 feet below crust of lake; cones 

 blackened but no trace of fusion. 



Jan. 16 — Six Seger cones of fusibilities 770° C. to 990° C, im- 

 mersed 30 minutes, 3 feet below crust of lake ; (fig. 16«) 

 apparatus frozen into crusts and incandescent pipe rent 

 asunder in the effort to recover apparatus by twisting. 

 Cylinder containing cones lost (fig. 17c). 



In all these tests the cones were held by their bases in a 

 special riveted iron container so that the tips were free within 

 a three-inch (eight centimeters) steel cylinder eleven inches 

 (28^^"^) long, covered with a screw cap at the lower end and 

 screwed on a one-inch galvanized steel pipe at the upper end. 

 This pipe, 20 feet (6 meters) long, was open at its upper end 

 and was used as a handle for thrusting the cylinder beneath 

 the lava. A rope was attached to the upper end of the pipe 

 so that several men could pull in recovering it. 



These tests were surprising, especially that of January 15, 

 when a cone, of fusibility 770° C, wholly failed to fuse though 

 immersed three feet beneath the surface in the quiet streaming 

 lava of the lake for eleven minutes. 



On the same day, January 15, two temperature readings 

 were made with Bristol portable pyrometer, a commercial 

 thermo-element. The element, without covering, was thrust 

 directly into the liquid lava at the edge of the lake and left 

 there until the recording needle of the galvanometer came to 

 rest. The first trial gave maximum temperature 860° C, the 

 second trial 910° C. The upper end, or " cold junction," of 

 the apparatus was necessarily hot exposed in air to the radiant 

 heat from the surface of the lake and the rampart. The 

 makers furnish no correction chart for this source of error, 

 and hence the actual temperatures, if the instrument is 

 accurate, were somewhat higher than the figures recorded. 

 But the range exhibited by the thermo-element, though higher 



