168 



MR. J. MARTIN ON THE TERRACES OE ROTOMAHANA. 



over in ripples of about one inch in depth ? frequently the overflow 

 would cease, fluctuations continuing within the basin ; and 

 occasionally the water retired altogether within the tube, leaving 

 the basin dry. 



During rapid alternations of activity and rest the whole contents 

 of the Cauldron have been observed to retire within the tube in sis 

 hours, and the most rapid refilling noticed has taken four hours to 

 complete. 



The process of refilling sometimes commenced slowly and was 

 continued steadily, while at other times the action would be spas- 

 modic, and violent eruptions of water would be thrown to an 

 enormous height, sometimes falling beyond the area of the basin. 



Erom the measurements taken of the interior of the Cauldron, its 

 capacity would be about 2| million gallons. 



Prom numerous and independent observations the activity for 100 

 days may be stated as : — 



days. 



1. Excessive. — Violent disturbances, basin filling in 4 hours 



with overflow of 600,000 gallons per hour 2 



2. Extraordinary. — Basin filling in from 6 to 12 hours, overflow 



from 200,000 to 400,000 gallons per hour 8 



3. Normal. — Constant ebullition in basin, dense steam-clouds, 



frequent geyser-fountains from 20 to 30 feet above surface, 

 water welling over in rippling waves at 100,000 gallons 

 per hour 75 



4. Eeeble. — Reduced geyser-action, water rising and falling 



within the basin, little or no overflow 10 



5. Quiet. — Water low, showing floor of basin 3 



6. Dry. — Water all retired within the tube « 2 



100 



Heavy X.E. weather, with falling barometer, was usually associated 

 with excessive action ; the water frequently retired, leaving the 

 basin dry, when the wind was from the south, with a. clear sky and 

 rising barometer. 



Closely comparing the movement of the aneroid with the period- 

 icity of action gave, however, very unsatisf acton 7 results. Eor three 

 days the activity of the Geyser exactly corresponded with the 

 movement of the barometer — overflow ceasing and the water 

 retiring into the tube when the barometer was rising and wind 

 changing from W. to S., and activity being resumed directly the 

 barometer indicated a downward tendency and the wind shifted 

 toward N.E. 



On three following days similar changes of activity took place 

 under exactly opposite conditions as to wind and barometric pressure. 

 During six days succeeding the overflow continued normal, although 

 similar atmospheric changes were experienced. 



