目次へ
Following is an abstract from a report of Dr.Bolton,H.C:
Trans.New York Acad.Sci.,Vol.10,28-35(1890)
"Researches on Musical Sand in the Hawaiian Islands"
As a natural curiosity the place has a world-wide fame, but the printed
accounbs are rather meager in detail, and show their authors to have been
unacquatinted with similar phenomena elsewhere.
On the southwest coast of Kauai, in the district of Mana, sand-dunes attaining
a height of over 100 feet extend for a mile or more noorly Parallel to tho
sea, and covering hundreds of acres with the water-worn and wind-blown fragments
of shells and coral. The dunes are terminated on the west by bold cliffs
(Pali) whose base is washed by the sea; at tho east end the range terminates
in a dune more symmetrical in shape than the majority, having on the land
side tho appearance of a broadened truncated cone. The sands on the top
and on the landward slope of this dune (being about 100 yards from the sea)
possess remarkable acoustic propertics, likened to litte bark of a dog.
The dune has a maximum height of 108 feet, but the slope of sonorous sand
is only 60 feet above thc level field on which it is encroaclling. At its
steepest part, the angle being quite uniformly 31°, the sand has0 a notable
mobility when perfectly dry, and on disturbing its equilibrium it rolls
in wavelets down the incline, emitting at the same time a deep bass note
of a tremulous character. My companion thought tho sound resembled the hum
of a buzz-saw in a planing mill. A vibration is sometimes perceived in the
hands or feet of the person moving the
sand. The magnitude of the sound is dependent on the quantity of sand moved,
and probably to a certain cxtent upon the temperature. The drier the sand
the greater the amount possessing mobility and the louder the sound. At
the time of my visit the sand was dry to the depth of four or five inches
; its temperature three inches beneath the surface was 87°Fahrenheit, that
of the air being' 83° in the shade (4:30 p.m.).
When a large mass of sand was moved downward I heard the sound at a distance
of 105 feet from the base, a light wind blowing at right angles to the direction.
On one occasion horses standing close to the base were disturbed by the
rumbling sound. When the sand is clapped between the hands a slight, hoot-like
sound is heard ; but a louder sound is produced by confining it in a bag,
dividing the contents into two parts, and bringing them together violently.
This I had found to be the best way of testing sea-shore sand as to its
sonorousness. The sand on the top of the dune is wind-furrowed and generally
coaser than that of thc slope of 31°, but this also yielded a sound of
unmistakable character when so tested. A bagful of sand will preserve its
power for some time, especially if not too frequently manipulated. A creeping
vine with a blue or purple blossom (kolokolo) thrives on these dunes and
interrupts tho sounding slope. I found the main slope 120 feet long at its
base, but the places not covered by this vine gave sounds at intervals 160
paces westward. At 94 paces further the sand was non-sonorous.
The native Hawaiians call this place Nohili, a word of no specific meaning,
and attribute the sound caused by the sand to the spirits of the dead, uhane,
who grumble at being disturbed; sand-dunes being commonly used for burial
placcs, especially in early times, as bleached skeletons and well-preserved
skulls at several places abundantly show.
Sand of similar properties is reported to occur at Haula, about three miles
east of koloa, Kauai; this I did not visit. but, prompted by information
communicated by Hon. Vladimar Knudsen, of Waiawa, I crossed thc channel
to the little-visited island of Niihau. On tho western coast of this islet,
at a place called Kaluakahua, sonorous sand occurs on the land side of a
dune about 100 feet high, and at several points about 600 to 800 feet along
thc coast. On the chief slope, 36 feet high, the sand has the samc mobility,
lies at the same angle, and gives when disturbed the same note as the sand
of Kauai, but less strong, thc slope being so much lower. This locality
has been known to the residents of the is land for many years, but has never
been before announced in print. This range of dunes, driven before the high
winds, is advancing, southward, and has alreacly covered tho road formarly
skirting the coast.
The observations made at these places are of especial interest because they
confirm views already advanced by Dr. Julien and myself with regard to thc
identity of the phenomena on seabeaches and on hillsides in arid regions
(Jebel Nagous, Rig-i-Rawan, etc.). The sand of the Hawaiian Islands possesses
the acoustic properties of both classes of places ; it gives out the same
note as that of Jebel Nagous when rolling down the slopo, and it yields
a peculiar hoot-like sound when struck together in bag, Iike the sands of
Eigg, Manchester, Mass., and other sea-beaches a property that the sand
of Jebel Nagous fails to possess. These Hawaiian sands also show how completely
independent of material is the acoustic quarity, for they are wholly carbonate
of lime, whereas sonorous sans of all other localities known to us (now
over one hundred in number) are silicious, being either pure silex or a
mixture of the same with silicates, as feldspar. '
In 1875 Dr. James Blake, of San Frahcisco, examined microscopically a specimen
of the Kauai sand sent him by Mr. Frink, and ascribcd its acoustic qualities
to thc cellular character of the grains. This condition, however, Dr. Julien
and I fiud to be exceptional, since most sonorous sand is quartzose, and
we believe the gaseous-film theory, already announced to the Academy, applies
equally to sonorous sand of diverse form, composition, and origin.
A speccimen carried away in a bag, and another shipped over land in a keg,
have both preserved their acoustic qualities up to data.
[ The speaker exhibited specimens, and obtained a low hoot like sound by
clapping together sand confined in a bag. The subject was also illustrated
by numerous original photogrnphs (projected on a screen) of the Nohili,
and of scenery on the island of Kauai.]