Mower County transcript. [volume] (Lansing, Minn.) 1868-1915, 1873-05-15
AMERICAN FOG SIGNALS.
A Novel Phe no,neno,i or Sound:

Novel Phenomenon Of Sound: Il
An English official committee recent
~ visited Canada, and: the United
States, to make an examination Of the
fog Signals in use. They found the
signals of Canada good and effective,
and of great benefit to the trade.
The London Times says
- In tina States great attention has
been paid to fog signals, Fog may be
said to be the normal condition Of the
coast for half q year or more, and ship
masters cannot afford to be delayed by
it. but take til risk of running on by
the help of fog signals, even in crowd
ed track but undoubtedly great risks
attend this kind of navigation, some.
times ending in serious; disasters. In
the United States, as with us. the bell
is generally applied only to, places
where OTHER signals cannot be convent.
emily used: The most powerful signals
in use next to the gun are the horn and
whistle. OF tho horn there are two
kinds-np rle]y, that of Dabol1, worked
with mir, and the siren, worked by
steam. The whistle is of the ordinary
shape us ed in England. but is used to
give hparse, low-pitchea blast, in
stead OF 2 shrill one. the note being
regulated as desired. But this note
is never used for purposes of distinc:
tio1; as with us, the distinctive fea-
tnres are in the interval between the
blasts, and sometimes in the volume.
depending on the consumption of coal
and diameter of the cylinders. Each
and all OF these instruments do good
service on the American coasts. At
Portland the committee, steaming out
to wlndward, heard all the instruments
distinctly ut six miles. The New York
Lighthouse Board state that siren is
reported as having been heard for 26
miles In calm, but against q strong
gale the greatest distance does not ex-
coed two and half miles. Professor
Henry, chairman of the United States
Light House Board, in. mentioning
some experiments he had made, OBJ
served that the sound of the whistle is
only that of resonant cavity, and in.
stanced his having made bells of wood.
The committee noticed that the site for
q fog signal must be chosen that no
point, or cliff shall intervene and inter-
fere with the arc of sound. They oh:
serve that all the horns and whistles
they heard, may with care and atten
ton, be relied upon, when under vay.
to range of from two to eight miles.
acco lding, to the direction and force OF
the wind. They are often reported
as heard ct a greater distance, butt is
generally by persons who by previous
knowledge were prepared tor the
sound. The comnittee consider several
points clearly established in their trial,
and experiments that up wind the
reach of sound is very limited, dim.
finishing with the increased Of forcefoi
wind, while very little obstructs il
altogether that sound travels as ia,
when projected across as down the
wind, il. not further; that sound i,
sometimes strangely DETECTED accord.
ing to some unknown law, and it wa,
frequently observed to be stronger a,
a greater distance than in the inter
mediate range "A point which Prof
Henry proposes to investigate; tba
the listener is assisted by standing i,
front of q flat surface of wood, inter
cepting the sound and causing it K
reyerberate to the ear; and that tn,
sounds of the air trumpet, the steam
siren: and the steam whistle (all pitche,
at q low note, as found from experienc
the best adapted for carrying SCUM
further) differ SO little, that the mari
ner at sea, just getting within rang
of the sound. would be entirely unabl
to decide which instrument was heard
land that for purposes of distinction tn
only trustworthy guides are variation
in the number and length OF blast
and intervals