Independent Action of Side Pools. 



iSi 



iuvolved more than half of the crater area. In all these cases, Dana Lake, the New 

 Lakes, etc., Halemaumau seems to be not only the source but also the sinkhole. 



The lava in these side pockets, shallow as they are, seldom exceeding fifty feet 

 in depth, contains within itself all the forces needed to throw up fountains, open cracks, 

 remelt crust, etc., that the main Halemaumau possesses. These surface pools act as 

 relieving reservoirs, and suggest that there must be others beneath the crust to account 

 for the sudden changes in level in the main lake observed by so many visitors. A fall of 

 four feet in a pool a thousand feet in diameter means the transfer of a very large amount 



FIG. IIU. HALEM.\UMAU IN OCTOBER, l8qi. 



of matter and the exertion of a corresponding force. I have seen such a fall take place 

 within three minutes time, and there was no sensible change in sound or motion, so far 

 as the banks were concerned; the return in the case noted was slower, but it has been 

 observed by others to come back as quickly as it went, indicating that the relieving 

 reservoirs were not far away. From this excursus we must now return to the record. 



April lo, i8gi. H. M. Whitney. — About ii p.m. this day the fire returned in the sunken 

 pit of Halemaumau after having been extinguished thirty-five days. When first inspected on the 

 I ith April the fire was very small, occupying or puffing out of a small hole at the bottom not more 

 than four or five feet in diameter. 



May ig, i8gi . W. R. Castle. — The pit is now 2000-2500 feet long and nearly as wide, greater 

 axis N.E.-S.W. The inverted apex has now filled up with fresh lava to a depth in the centre of 

 about 75 to 100 feet. [Reports intermittent e.xplosious at intervals of five or ten minutes.] 



June 2g, iSgi . Work completed on the new house. [See Fig. 109 on opposite page.] 



August 8, i8gi. Telephone line from Hilo completed. 



[559] 



