OF THE HAWAIIAN ISLANDS. 377 



In several places the Wailuku has pierced the beds of lava, and in one place " 

 passes beneath a thick rock-bridge several hundred feet wide. Often where 

 the water flows over beds of compact dark gray basalt, masses of trachyte 

 closely resembling syenite, have formed pot-holes, and by mutual action have 

 been worn to pebbles. A remarkable series of these pot-holes occurs some five behind a Fail on 

 miles up the river. These are three circulfir pools in a bed of columnar basalt, the W;,iluku 

 each about fifty feet in diameter, and separated by walls about six feet thick. During high 

 water the river rises sometimes thirty feet and completely hides the pools, filling the ravine 

 in which they occur, but during the low water in the dry season, the upper bed is bare, and 

 after a succession of cascades of various heights the river pours into the first basin (A) from 

 a height of thirty feet, filling it with foam. From this there is no visible outlet, but fern 

 leaves thrown into it soon come out in the second near one side, where a few bubbles alone 

 disturb the tranquillity of the clear deep pool. From this to the third there are two sub- 



II *± 



Fig. 30. Plan of Pot holes in the Wailuku. Fig. 31. Longitudinal section of Pot-holes. 



terranean passages, one on each side, and the water escapes at last over a fall some forty 

 feet high, nearly covering a perfect Gothic arch which forms the entrance to a shallow cave. 

 The whole series is enclosed by high and almost perpendicular walls, not unlike those of 

 Trenton Falls in New York. 



In many places where recent lava-streams have flowed into the river and been broken up, 

 the sand and chrysolite resulting have been washed to the sea, and are there thrown up in 

 the clefts along shore, and such large deposits of the green sand are sometimes found, that 

 it has been used in mortar to lay the furnaces and pans of a sugar-boiler — a purpose for 

 which it seems well suited from its refractory nature. Quartz crystals have been found in 

 masses of lava, but are mostly small, although clear and perfect. 



The coast of Hawaii from Hilo to Laupahuehoe, a distance of thirty miles, consists of 

 a precipice from one to five hundred feet high, and extending to nearly the same 

 depth beneath the water, so that in calm weather, large ships may approach close to the 

 cliff The road runs somewhat inland, and is one of the most remarkable in the world. 

 Ravines, eighteen hundred or two thousand feet deep, and less than a mile wide, extend- 

 ing far up the slopes of Mauna Kea, streams liable to sudden and tremendous freshets, 

 must be traversed on a path of indescribable steepness, winding zigzag up and down the 

 beautifully wooded slopes which are ornamented with cascades of every conceivable form. 

 Few strangers, when they come to the worst precipices, dare to ride down, but such is the 

 nature of the rough steps that a horse or mule will pass them with less difficulty than a 

 man on foot who is unused to climbing. No less than eighty-five streams must be crossed 

 in a distance of thirty miles. 1 The amount of water is great, and the soil is often so soft 



1 The following description of a passage over part of this rivers would be impassable early in the morning, but that the 



road may convey a better idea of its rugged nature. It is water would rapidlv subside. We waited until half-past eight, 



taken from the author's journal: — and then rode on, the Road Supervisor, Mr. R, having pre- 



" During the night it rained hard, and we were told that the ceded us more than an hour. We crossed two or three small 



MEMOIRS BOST. S0C. NAT. HIST. Vol. I. Pt. 3. 96 



