Evening star., 1896-03-07

~
N \UN~ blind, but deaf as
~ w well, and Is perforce
compelled to trust solely in Providence for
the safe deliverance of himself and crew
and the ship and cargo. From the earliest
history of the world when men first began
to go down to sea in ships efforts have been
made to counteract the dangers of naviga-
ton 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 fogs. 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 fogs are sirens,
trumpets, steam whistles. bell boats, bell
buoys, whistling buoys, bells struck by ma
chinery, cannons, rockets and gongs. These
devices serve a useful purpose, but do not
fill the bill by many degrees. They form
part of the equipment of our light house
establishment. than which there is no bet
ter in the world, but were not sufficient to
avert the accidents that recently befell the
steamer 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
signals when she was run into and sunk
by the BOurgogne.
Views of an Expert.
These are only specimen cases. They oc-
orrred in familiar waters, and mainly
attributable to fogs. The case of the Alsa
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 aber-
ration in audibility.
The difficulty of determining the source
of the sound of fog signals at sea has been
felt since the earliest days Of civilization
and has not yet been overcome. Mr.. A. B.
johnson, chief clerk of the light house
board, who is recognized as an authority
on all questions pertaining to aids to navi-
cation, advanced some interesting ideas
this subject IN conversation with 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 deer, and the sound INDICATES
identity and proximity. but not direction.
The hunter waits for repeated renewal of
the sound to ascertain its exact position,
and even then verifies his addition by his
vision the hunter by his camp fire may
aim between the luminous dots of reflected
light, which he knows to be the eyes of
Wolf, but he would scarcely be able to aim
at OF even very near that spot Oh simply
hearing the howl from the wolf that owns
the eyes.
"The pIainsman hears a shout in the dis
tance- He may recognize 1t as the voice of
comrade and fix the general direction as
north. east, south or west, but hardly more.
He may short back, and the two may come
together; but if it be dark and there is no
fire or other signal. the shouting back and
forth must be frequently repeated. and
varied from simple to a complex sound.
~ ITln hn of hfn
auditiCn, eliminate his personal equation,
and the sound will appear to swing. pendu-
lum-like, right and left, with shorter and
shorter stroke, till the comrades come to-
gether.
Uncertainty of Sound.
''The average child. returning from
school, on entering the house, calls Mann
mar The mother, perhaps, replies, 'Yesr
Where are you? is the next question, and
the reply informs the child not only as to
the floor. but as to the room in which the
mother can be found. The child cannot de-
termine its mothers location by the sound
of her voice. This exaggerated instance
may b owing to the reflection of the
sound. not only from the walls, but from
the strata of air differing in temperature
and humidity.
How many of us going to the next
street, running at right angles to the car
tracks. tell, from hearing the bell of
the approaching street car before the car
comes in sight, whether that car is going
north south? 1t does rot seem that ami
mails can determine the direction OF sound
much better than man. The sleeping dog,
reused by his masters call, is all abroad at
his masters location, ard determines it by
sight or scent, 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 or
other birds. on hearing a gun, Is as likely
to fly toward as from the sportsman, if he
has kept entirely out of sight and the fash
of his piece has not been seen.
1T is a question whether the blind are
better able IL dete: Nine the direction of
sound by ear than are seeing people. 1t is
possible that their senses of touch and smell
are so highly developed that their instan-
taneous action with that of the ear gives
them a decided advantage over seeing peo-
pie in this matter. 1 have known blind
man to be so sensible of the current of air
put in motion by the speaking of a single
word in a room that he could select the
speaker by his location though others were
present. So, too, / have known blind man
to locate and identify the various people in
the room. he saying he did it by the differ
ent scent evolved from each the seeing
people there not being sensible of any scent
from any one And yet he, when standing
In the middle of the room with his nose
stopped. could not give the direction of one
single speaking person.
Not Always the Apparent Direction.
Among our erroneous popular notions is
one which occasionally brings practical
men, even shipmasters, to grief 1t Is the
idea that sound is always heard in all di-
rections from it's source according to it's
intensity or fierce, and according to the
distance of the bearer from it. Instances
OF this fallacy have accumulated. and they
are emphasized by shipwrecks caused by
the tnsistence of mariners on the infaIli-
piity OF their ears. who have accepted un-
Questioned the guidance of sound signals
during fog as they have that of light HOUSES
during Gear weather. The fact is, addition
Is subject to alterations, and under cir
cumstances where little expected. We have
learned by sad experience that implicit re-
lance on sound signals may, as it has,
lead to dar ger if not to DEATH
THE late Prof Henry of the Smithsonian
institution, who made a special study of
this subject, formulated his conclusions on
these abnormal phenomena as follows: Cd
The audiblity of sound at a distance and
Its inaudibility nearer the source of sound
90 The inaudibility of sound at given
distance in one direction, while lesser
sound is heard at the same distance in
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