OF THE HAWAIIAN ISLANDS. 443 



Hawaiian volcanoes, but have been observed on these shores at times when the volcanic 

 vents were not unusually active. 



The first recorded took place in May, 1819, when the tide rose and fell thirteen times in 

 the space of a few hours. The elevation was not very great, nor was there any earthquake 

 shock on the land. On the 7th of November, 1S37, a more remarkable commotion took 

 place. At six o'clock the sea retired to a depth of eight feet, leaving the reef surrounding 

 the harbor of Honolulu quite dry. The water then slowly returned, and in twenty-eight 

 minutes had risen to the height of an ordinary high tide. Without a pause it again fell six 

 feet, and this ebb and flow was repeated at intervals of twenty-eight minutes. At the third 

 flow it rose four inches above ordinary high-water mark, and fell again six feet four inches. 

 After the fourth flow the motion became irregular and gradually diminished, but did not 

 return to the ordinary course of the tides until the next day. The meteorological observa- 

 tions do not show any extraordinary disturbance in the atmosphere. 1 



11p.m. Thermometer 74°. Fahr. Barometer 30.04. 



11.30 p. m. " 73.5°. " " 30.03. 



At Kahului on the windward shore of the Isthmus of Maui, the sea retired suddenly 

 twenty fathoms. The natives followed with delight picking up the stranded fish, when 

 suddenly the water rose like a wall before them and overwhelmed them in a wave which 

 swept up on the shore destroying the village. Happily only two lives were lost here, as 

 the people were quite at home in the water. At Hilo the first fall of the water took place 

 at half-past six, half an hour later than at Honolulu, and the returning wave rose twenty 

 feet above high-water mark. 



May 17th, 1841, a similar although less violent commotion of the sea took place. In the 

 harbor of Honolulu at twenty minutes past five p.m., the water was observed to be "dis- 

 colored and breaking like a tide rip." It then fell rapidly, leaving the reef and portions of 

 the harbor bare. Twice during forty minutes this ebb was observed, and the sea then 

 assumed its ordinary appearance. At Lahaina, nearly a hundred miles distant, the first ebb 

 was almost simultaneous, but the rise and fall was quite rapid, at intervals of four minutes. 

 It is said that a similar sea-wave occurred on the coast of Kamtschatka. 2 



The effects of such waves in undermining the cliffs along the shore must be very gi*eat, 

 and it was perhaps during one of these extraordinary tides that the loose craters on the 

 shores of Ka-ii were partially demolished ; certainly the cliffs were broken away in that 

 district by this means, and I am inclined to attribute to the same powerful agent erosions 

 on the lee shore of the other islands of the group. 



Magnetic effects of melted Lava. 



It would be most interesting to try the effect of a lava-stream in motion on the magnetic 

 needle. In the vicinity of the Halemaumau in Kilauea the needle of the theodolite compass 

 was strongly affected, and the variation at the different stations on the upper bank was 

 considerable but inconstant, doubtless owing to the presence of moving lava currents, as the 

 disturbance was most marked in the vicinity of the pools. In several cases the variation 

 has been noted on the map of Kilauea. (PI. XV). 



l Hawaiian Spectator, vol. i., p. 104. Observed by Dr. T. 9 Jarve9's History of the Hatvaiian Islands, p. 22. 

 C. B. Rooke. 



