NOTES ON THE igi6 ERUPTION OF MAUN A LOA 325 



the outbreak. Also a smoke ring is shown encircling the upper 

 part of the column below the crown. By eye observation the 

 writer did not notice this ring until about 7:50 a.m. Despite this 

 he feels confident that it had not begun to form when he first saw 

 the eruption cloud. 



After 7:50 a.m. the form of the eruption cloud underwent rapid 

 changes as the continued emanation of fumes added to its bulk, 

 and convection currents and varying winds at different altitudes 

 continually reshaped it. At 8:00 a.m. the diameter of the stem 

 had increased to from i| to if miles and the smoke ring, which had 

 rapidly enlarged, had begun to fray and spread horizontally about 

 equally in all directions, except for a slight elongation toward the 

 northwest, forming the striking mushroom shown in Plate II, b. 

 By this time the crown had reached a height of 20,000 feet, or 

 more, above the mountain profile, and its tip was just beginning to 

 fray in the upper wind. 



At a little after 8:00 a.m. the uprush of fumes began to dimish, 

 and by 8:30 the two dominant columns were again separated, and 

 the subordinate columns had ceased to rise continuously. The 

 fume cloud had spread rapidly at the level of the smoke ring, 

 forming a cloud blanket, and this, with the fraying and drift to 

 eastward from the summit of the crown, gave rise to the beautiful 

 cloud-form shown in Plate II, c. This has been likened aptly to a 

 ballet dancer. The emanation of fumes continued to diminish 

 rapidly, as is emphasized in the view (Plate II, d) taken at 9:05 a.m. 

 Only a graceful cloud-form then remained, with thin columns of 

 rising fumes. 



By 10 a.m. (Plate III, a) it required keen observation to detect 

 any further output of fumes; and by 10:30 this could be made out 

 only by experienced eyes. By 11 :oo a.m. the action was doubtful, 

 and it grew more and more doubtful afterward — though cloud- 

 forms occasionally appeared where undoubted fume columns had 

 been rising. By noon nothing could be seen but a frayed stratum 

 of high cloud overspreading the sky above the mountain. This 

 exhibited ripple-marking, like cross-waved cirrus. It persisted 

 until after sunset. 



