The morning news. [volume] (Savannah, Ga.) 1887-1900, 1890-07-09
TIE BARKING SANDS.
What Prof Bolton Says of His Inves-
tioatiOn.

! WnaL ErOf Bolton says or bis lnVeS-
tigation.
From the Honolulu Commercial advertiser.
The so-called barking sands of Kauai
are mentioned in the works of several trav-
elers in the Hawaiian ISLANDS, and have a
worldwide fame as a natural curiosity; as
a rule, however. the printed accounts are
mea ger in details and show the authors to
have been unacouainted with similar phe-
nonena elsewhere.
Jointly with Dr. Alexis A. Julien Of Co
| lumbia College, New York, | have been
| studying the properties of sonorous sand
| for long time and have visited many
localities in America. Europe and Asia;
| hence | was able during a recent visit to
Kauai to make some notes and comparisons
that may interest the residents of this
| kingdom.
Notwithstanding recent rains, l found the
sand on the dune at Mana day to the depth
| of four or five inches, and when pushed
| down the steep incline 1t gave out a deep
! bass note having a tremulous character.
| This hardly resembled the "barking" of o
dog, but sound somewhat like it is pro
duced by plunging the hands into the sand
| and bringing them vigorously together.
Another way is to fill a long bag three
| quarters full of sand, and then, divid-
| ing It's contents into two parts, holding
| one IN each hand, to clap the two por-
tons together. This | had found to be a
| good method for testing the sonorousness of
| sand and sea beaches. A bag of the sand
| will preserve its acoustic qualities long
time if kept dry and not too frequently
manipulated. The angle at which the sand
| lies where it falls over the dune is 81 the
| sonorousness extends several hundred feet
along the dune, being interrupted by a
ere ping vine that .thrives marvelously in
| such soil.
A similar dune of sonorous sand occurs on
| Nuhau, as has long been known to residents
of the island, and 1t has been also reported
to occur near Koloa.
These observations, simple as they are,
have been of special interest to me because
they show that the sand of these localities
forms link between that of the sea beac ues
aud that of certain hill on the Gulf of
Suez known as label Nagous, and which |
visited in April, 1889. Sonorous sand is of
more common occurrence than generally
supposed; it is found on the Atlantic coast
of the United States from Maine to Flor
ida, on the Pacific coast, ia Europe,
Japan, Africa, Tasmania, etc., as
well as on the shores of many
fresh water lakes. In those localities it
forms areas generally between low tide and
the base Of adjoining dunes, and emits
sounds only when subjected to friction by
the feet or hands, or in a bag as described.
AT label Nagouse, in Arabia, on the other
hand the sand rests in a ravine, and pro-
duces sound only when it rolls down the in
cline (which it often does spontaneously
and fails to respond to kicks and cuffs. The
sand at Mana, as shown, unites in itself
both these acoustic properties. The
angle at which the sand lies at label
Nagous is the same as at Mana, 81 degrees
being the "angle of rest for fine dry sand.
The musical notes obtained at these far
separated localities are also the same, but
| 4 - i. =. e.. III
| consequently the sounds are far louder,
especially as they are further magnifed by
being echoed from adjoining cliffs
| The sand of Kauai AID Nllhau is made up
of fragments of shell and coral, while that
of all other localities known to us over 100
in numberl is siliceous. This shows that
the sonorousness is independent of material.
Examination under the microscope further
shows that the sonorous quality is not con-
nected with the shape OF the grains. So
norous sand is distinguished by being re-
markably free from fine dust or silt; the
individual grains aBe very uniform in size
II is very easy to deprive sand of its acou-
site power by mixing a little earth with it,
or by wetting it. 1t is dilficult-if not i'm
possible-to restore to sand its sonorous
qualityswhen once killed.
A number of hypothesis have been pro-
posed to explain the cause of this curious
property of certain sands. The prevalent
idea in these islands that the sound is due to
the cellular structure of the sand, must be
abandoned since most sonOrous sand is not
so constituted, that of Kauai forming an
exception. Some have attributed the
sonorous quality TO saline crusts, others to
electricity, effervescence of air between the
particles and to solariZation and one author
attempts to explain the phenomenon by
writing of "a reduplication of impulses set
ting air in vibration in a focus of echo"
These theories DR.. Julien and reject for
reasons l cannot here detail, and we believe
the true cause Of sonorousness to be con-
nected with thin pellicles or films of air or
of gases thence derived, deposited and con-
densed upon the surface of the sand grains
during gradual evaporation after wetting
by seas, lakes or rains. By virtue of
these films the sand grains become separated
by elastic cushions of condensed gases,
capable of considerable vibration, and
whose thickness we have approximately de-
J termined. The extent of the vibration and
the volume and pitch of the sound thereby
produced we also find to be largely depend
ent upon the forms, structures and surfaces
Of the sand grains, and especially upon their
purity and freedom from fine silt or dust.
We have shown that the pitch of the
musical notes obtained on sea beaches is
proportional to the mass of sand moved,
the greater the mass the lower the tones; on
the dunes of Kauai and Niihau the same
holds true Those who wish to learn more
details of our Investigations can find alb
stracts of three papers read before the
American Association for the Advance
ment of Science in the proceedings of 1888,
1884 and 1889