Savannah morning news. [volume] (Savannah) 1868-1887, 1885-06-05
AIR SOUNDING FOR ICEBERGs.
An Apparatus by Which An Echo Can
Be Heard in Time TO Avoid Coli

sion.
From the yese York Herald.
WASHINGTON. June 2.-The presence
Of an Unprecedented number Of icebergs
in the Northern Atlantic this spring and
the Importance Of furnishing a means by
which vessel at sea can avoid objects of
any kind in its path led Prot. Alexander
Graham Bell to bring the recent discoy-
cries Of Mr.. Frank Della Tore, OF Balti-
more, before the National Academy of
Sciences at its last meeting. The follow
ing letter from his pen, which viii APP
pear IN the Science on Friday, gives de-
tailed account of the experiments made
on the river Patapscoa few weeks ago:
Inc recent accident 10 the steamer City
Of Berlin emphasizes the Importance Of
deYislng practical methods Of ascertain
Ing the proximity OF icebergs in a fog. The
precautions taken by the Captain, though
they saved the lives Of more than 1,4G0
passengers and prevented serious danger
TO the vessel, did not preYentcOntact with
the berg. Even the outlooks were unaware
OF the proximity OF the iceberg until it
was actually upon them.
Under these circumstances the method
proposed By Mr.. Frank Della Tore, of
Baltimore. deserves consideration. His
experiments indicate that il maybe pos
sible to obtain an echo from an iceberg
when in dangerous proximity TO a snip.
Mr.. Della Tore believes that even an
object Offering so small a surface
as floating wreck may be detected
this way during a fog in time to
prevent collision. However this may
be, it is certain that his method is worthy
OF trial at sea, and that preliminary eX-
periments recently made in the presence
OF Prof. Rowland, Of the Johns Hopkins
University, and the writer, have demon
strated the feasibility Of producing well
marked echoes from schOOners and river
steamboats, at considerable distances
away.
The experiments were made on the
river PGtapsco, near the head of Chesa-
peake bay, at point about seven miles
from the city of Baltimore. The party
proceeded down the river in a steam
launch to the selected place, where the
distance from shore 10 shore appeared to
be about three miles. The launch was
kept so tar from land as to prevent the
possibility Of mistaking a shore echo for
that obtained from a passing vessel. The
apparatus employed consisted of a
musket, TO the muZzle OF which a speak
ing trumpet had been attached. This gun
was aimed at passing vessels and blank
cartridges were fired. After longer or
shorter time distant echoes were re-
turned. The river steamboats, and pass
ing schooners returned perfectly distinct
echoes about a mile distant. At shorter
distances the effects were, of course, still
more striking.
In order to test the minimum size of
object that would produce a sensible echo,
number of shots were fired in the direc-
ton of an approaching tugboat which APP
preached bow on. Even IN this case
feeble echo could be perceived when the
tugboat was estimated to be a quarter of
mile distant. In this case the sound
was heard only by the closest attention,
but IN the case oflarger vessels the effects
were very distinct.
Experiments were made which demon
strated the fact that the speaking trumpet
attached TO the gun materially assisted in
giving direction to the sound impulse and
in intensifying the effect. Mr. Della
Tore claims that steam whistle or siren
apparatus for projecting the sound i'm
pulse directly ahead of a moving vessel
will prove as ef1cacious as the firing of a
gun.
In some of the experiments a prolonged
rumbling sound resembling thunder was
heard when the gun was fired. The sur
face Of the water was at the time covered
with ripples, only the effect was less
marked than when the water was smooth.
The sound may therefore have been caused
by the wayelets in the water, in which
4 case it is probable that this kind of sound
may prove distur bling element of i'm
/ pOrtance when the experiment is tried
1 upon rough sea.
ALEXANDER GRAHAM BELL.
MIR. Della Tore states that mis- expert
ments have been tried in deep sea and
have been perfectly satisfactory. He has
already succeeded in getting percepti-
/ ble echo from an iceberg, He has in
vented an apparatus for the intensified
ton OF the sound of the echo as it re-
turns to its starting point. 1t thus ap-
pears that by very simple apparatus
collisions at sea can be avoided.