150 



SCIENCE 



[N. S. Vol. XLII. No. 1074 



shape. During the day the southwest and west 

 ponds filled up and overflowed, but the main 

 lake remained about 4 feet below its banks. 

 The streaming was from east to west, with 

 fountains bursting to a height of 40 feet at 

 Old Faithful. The level of the lake on Janu- 

 ary 6 was 368 feet, and about 10 feet below 

 its walls. The southwest pond had become an 

 oval pit 20 feet deep with a sunken black crust 

 for a floor. Molten lava poured over one 

 corner of the floor and a fountain played in 

 another. The west pond was crusted over. 

 The northwest pond was active. 



With the subsidence on January 7-8, the 

 floor began to crack. The following day the 

 lake was 15 feet below the floor and a large 

 crack had developed near the southwest shore 

 of the lake. In the east pot, a continuation of 

 the southeast cove, the lava was streaming 

 southeast. The southwest pond remained a 

 pit; the west pond had a dim glow; and the 

 northwest pond remained active. On the 11th, 

 there was a small flow southwestward from 

 the west pond. The next day there were evi- 

 dences of subsidence in the enlarging of the 

 pool, by inbreak on the north end of the east 

 arm; in slides; in blowing noises; greater 

 fountain activity and streaming. The lake was 

 495 feet long, the east arm 250 feet long from 

 its entrance, the depth 391 feet, with an inner 

 wall 28 feet high. 



On January 13 the east pot collapsed. The 

 southwest and west ponds were deep pits, the 

 latter smoking, but the northwest pond re- 

 mained active. The streaming on the 13th' 

 and 14th was from the east toward the west. 

 Eoek slides took place on the 15th and 16th. 

 On the 18th the bridge between the southeast 

 cove and the east pot collapsed. There was a 

 torrential inpouring, for a time, at the north 

 end of the east arm. Later there was a sudden 

 rise of 5 feet with a flow toward the west, and 

 a green-blue flame 5 feet high; followed in 15 

 minutes by a subsidence of 5 feet. The sink- 

 ing continued on the 19th with intense foun- 

 taining, streaming from the east arm, and 

 rock slides. On the 20th, lava cascaded into 

 the lake from an orifice 3 feet above the lake 

 level on the west side. The direction of 



streaming reversed suddenly several times, 

 with sudden small changes in level of the lake. 



Whirlpooling began on January 23, with a 

 whirlpool in the south cove, 100 feet in diam- 

 eter and a very rapid rotation counter-clock- 

 wise accompanied by a roaring noise. Torrents 

 were pouring from the east arm. The north- 

 west pond was active, but the other ponds had 

 ceased activity. The lake was 515 feet long, 

 160 feet wide, 440 feet below the rim; the east 

 arm was 420 feet long. The crag had become 

 flatter, sinking toward its original position. 



After a temporary rise on the 24th, and an- 

 other on the 27th, the lake was 436 feet below 

 the rim and the crag 376 feet on the SOth. 

 Caving took place on the north edge of the 

 lake, and on the next day at the east end of the 

 southeast cove. The southwest part of the old 

 floor subsided. 



Whirlpools were formed February 2—4, but 

 in neither case was the motion so rapid or so 

 violent or was there such a convexity to the 

 stream as on January 23. On each of the 

 three days in February a torrent poured from 

 the east arm or out of the southwest cove, at a 

 rate of 10 to 15 miles an hour, and developed 

 a powerful vortex near Old Faithful with a 

 clockwise rotation. Through the convex 

 stream, bubble fountains burst incessantly. 

 Back eddies were occasionally developed in the 

 south cove and at the west end. 



Slow subsidence continued during Febru- 

 ary, with the formation of concentric benches 

 by subsidence of portions of the 1914 floor, 

 and with active gas escape and fountaining, 

 which indicates a concentrated escape of the 

 gas and active convection. On the 11th, a new 

 1915 bench was built by a temporary rise. The 

 west pit had become continuous with the 

 northwest, and later it became joined by a 

 trench with the east arm, which froze over by 

 the 18th, and ceased to be a part of the lake. 

 By the latter date, a depression had developed 

 across the south side of the pit. New smoke 

 holes had developed in a number of places, 

 and these, together with fumaroles on the 

 south side, make seeing difiSeult. The north- 

 west pond had crusted over and temporarily 

 ceased activity. 



