The Portland daily press., 1896-03-21
SOUND In FOG.
1t Is One Of The Uncertainties That
Haunt the Navigator.
CAUSE OF RECENT MARINE DIS
ASTERS.

ak with A. b. johnson, the Light House
Board Expert.
Washington Star
Fogs undoubtedly have caused more
marine disasters than any other meteoro-
logical condition. When they prevail over
the waters of the earth, the navigator
not only cannot see his coulse, but he
cannot rely upon his sense of hearing.
He is, therefore, not only blind, but deaf
as we'll, and is perforce compelled to trust
solely in Providence for the safe deliver
ance of himself and crew and the ship
aud cargo. From the earliest history of the
world when men first began to go down
to sea in ships efforts have been made to
counterfeit the dangers of navigation in
times of fog The genius of the world
has been devoted almost from the time
of Noah in devising means to protect
navigators when the waters are overcast
by fog. While the dangers of navigation
under such conditions have been greatly
reduced by various inventions, they are
still far from being removed entirely.
The sound signals now generally used
to guide mariners during fog are sirens.
trumpets, steam whistles, bell boats, bell
buoys, whistling buoys, bells struck by
machinery, cannons, rockets and gongs.
These devices serve usef ul purpose, but
do not fill the bill by many degrees.
They form part OF the eq dipment of our
light house establishment, than which
there is no better in the world, but were
not sufficient to avert the accidents that
recently befell the steamers st. Paul, New
York and Ailsa in the vicinity of New
York city. The st. Paul went out of her
course and ran aground at Long Branch,
the New York ran aground just outside
of Sandy Hook, and the Ailsa lay at an
ohor blowing fog signals when she was
run into and sunk by the Bourgogne
These are only specimen cases. They
occurred in familiar waters, and are
mainly attributable to fogs. The case of
the Ailsa in particular is only another
illustration of the difficulty of locating
sound when the atmosphere is charged
with the conditions peculiar to fogs.
Technically speaking the accident was
merely the result of an alteration In
audibility.
The difficulty OF determining the source
of the sound of fog signals at sea has
been felt since the earliest days of civil
ization and has not yet been overcome
Mr.. A. B. johnson, chief clerk of tile
light house board, who is recognized as
an authority on all questions pertaining
to aids to navigation, advanced some in
teresting ideas on this subject in con-
yersation with a Star reporter today.
Said he: The difficulty in determining
the true and exact direction of the sounds
we hear meets us in various ways. The
hunter hears the note Of bird, the hiss
or whistle Of O deer, and the sound indi-
Gates identity and proximity, but not
direction. The hunter waits for repeated
renewal of the sound to ascertain it's ex-
act position, and even then verifies his
addition by his vision. The hunter by
his camp fire may aim between the 1umi-
nous dots OF reflected light, which he
knows to be the eyes of wolf, but he
would scarcely be able to aim at or even
very near that spot on simply hearing
the howl from the wolf that owns the
eyes;
The plainsman hears shout in the
distance. He may recognize it as the
voice OF oomrade and fix the general
direction as north, east south or west,
but hardly more. He may shout back,
and the two may come together; but if
IL be dark and there is no fire or other
signal. the shouting back and forth must
be frequently repeated, and varied froIa
simple to complex sound, that each
Of hio
and eliminate personal equation, and the
sound will appear to swing, pendulum
like, right and left, with shorter and
shorter strokes, till the comrades come
together %hs - ,.,,
Mammal The mother. perhaps, replies,
'YssP Where are you?' is the nsxt
question, and the reply informs the child
not only as to the floor, but as to the
room in which the mother can DO found
The child cannot determine its mothers
location by the sound of her voice. THIS
exaggerated instance may be owing to
the reflection of the sound, not only from
the walls but from the strata of air differ
fng}in temperature and humidity.
"How many of us going to the next
street, running at right angles to the
car tracks, can tell, from hearing the
bell of the approaching street car beforr
WIZ Sfhl COluSo All Big WuoUuOI Dudu cttG
Is going north or south? 1t does noe
seem that animals can determine th.
direction Of sound much better than mans
Ine sleeping dog, reused by his MASTER
Gall. Is all abroad as to his masters loca,
tion, and determines it by sight or scentl
or both. frequently running in several
different directions before hitting the
right one. The deer, on being startled
by the unseen hunters tread, is not
always right in his selection OF the route
TO GET out OF harms way. A flock of
geese. ducks OF other birds, on hearing a
gun, is as likely to fly toward as from
the Sportsman, it he has kept entirely
out OF sight and the fash of his piece has
not been seen.
Among our erroneous popular notions
Is one which occasionally brings practi-
cal men. even shipmasters, to grief. 1T
Is the idea that sound is always ahead in
all directions from its source accordino
to it's intensity or force, and according to
the distance of the hearer from ii. Tn.
stances of this fallaoy have acoumnlatad
and they are emphasized by shinwreoEs
caused by the insistence of mariners on |
the infallibility of their ears. who hay