Telegram-herald., 1889-09-09
STEAM FOG HORNS
Queer Facts About the Conveying OF Their
Sounds in tho Air.

Queer Facts About the Conveying OF Their
Sounds in tho Air.
Poins Judiths siren is a damsel Of the first
class The fog horns extend their long.
black throats from the side OF the tog signal
house. hard by the light tower. and open
their mouths 70 the sea There are two OF
the sisters, each provided with boiler for
lungs and little engine, so that II either
gives cut, in lung power, the other may sing
In her place.
The governments fog sirens are among the
most interesting creatures Of the Lighthouse
service. They have been tho subject OF tho
study Of the services scientists for good
many years. They have been experimental
with, all sorts OF devices have been tried
with view % improving their serviceabn-
ity. and their position today in Importance
Is even Of seniority rank 70 the lighthouses
themselves But while the lighthouses are
pretty well perfected establishments, the fog
SIRENS. with ell the acoustic problems which
they give rise 70, are subjects Of the most in
teresting research, the utilized field of which
is still broad
Each Of the sister sirens at Point Judith is
sixteen feet long, tGpering from the throat Of
four inches diameter 10 the mouth, thirty
inches In diameter. There is a diaphragm
across the throat with four square holes nit,
and across this diaphragm and the square
holes whirls, az the rate OF !. 30 revolutions a
minute. an arrangement that Is like wheel
without the feuy. The steam is sent rushing
between the flying spokes and through the
holes, and goes reveberating along the six
teen feet OF cass iron neck and out OF tho BIG
mouth with a roar thai makes tho signal
house jump, and can be heard beyond Block
Island. 4 cam device on the engine lets
steam into tho SIRENS throat at intervals Of
forty seconds, and then the siren bellows
Continuously FOR six seconds The fog damsel
at Block Island lets & every thirty seconds
Instead Of every forty seconds, 50 that the
mariner who observes his chart can always
tel which shore he Is closer on by counting
tho intervals betwesn the fog sirens blasts.
The Importance of this difference OF interval
may not bo fully apparent 70 tho landsman.
and Is not always regarded 10y the mariner
guiding his ship blndly through impenetra-
bie fox. Aside from the impos1biiity Of a
master of a sailiug vessel maintaining a re-
liable .iaa of his position in a foz, where PER
haDs ho l. drifting more than saling the
contour x tns cast anf toe make of the
tides cat q 10 Sound Is such that he may
easily fnd himself sailing on 70 Point Judith
when ho believes ha Is cloae 20 tho Block Isl.
ard shore.
The development q The ziren has prsaonted
acoustic problems which, II really eEp.alna-
biz ~ acoustic and atmoerh-r.c principles.
have not been foroseen. and have bothered
tho eKperts when they ran against them. and
ara none the less curious now % the isy ob-
server. Moreover. the experts SIRE completely
f8lei il thrr Efforts 20 make tho siren do Tho
Vors that t vas thought &c could d. without
any trouble. although tbeY have found oat
wat the dLlcu'ty H. For instance. rita aIl
It's lung power. long throat sud big month,
ttat carry ia Believing far out into fbe ssa,
scnletiu mes the p0nior0us sound 9isapraars
utterly a. short distances. The sound FROM
ro.nt Jadl-h siren that reverberat-s .n tie
mariners ear away acroes t1 Bg1cx Island
mag not ts nsa~i ~ sl by tae Euf1rturate
skipper straninE rs ear Cor ia warn
blast a uile g shore Then sa3isriv. when
he les irft,d IN until Point julie Is too .a~s
On r'- lee r- escape from. tte thunder ~ -ts
siren bursts upcn hr1. a7t ns knows from rs
ponlerous tone That So = desperately near
TIE arsszerS are roaring on biz bow tlara
.s a1 uziF crunch. a cissh sni slirer. 7ad
ne aari and fast When ere LIFE ssrrT
crr~ e--s hiIn ssaors the 1rst targ ee es
IS t' 80 swearing Tssr sri chen e.
co-rCIsI tae a1tla-'-ss 81 81 7s r-.1
thar AZ 7n 1our on such q n-E p 80
te-ee f- .re f,r Erai cn Foint 5l.ii-s vas
ncr srrrI rx and ~ss oriT =,unded ~hen Il
wls -co .sts 20 rarn hin ~ Ia years E-e
~ ffa ant sseuer ~culd 10 asuss6 over t-e
cre 81 - srs s.rerrrh q -1nplaiats aks tr =
w tre aa.,orities Ue-sy r4-lre ~ tle
Hr-r .eerrr = Els sran vss ~1rslr- -r RI q
Tler sars --urd cue ~ experience sr3 CO
ricrs-rsfsf - t,re-ry .ssr t1a 1lIsrs1t cur
-rrs II sir piaT the tsuo~ wian 80 Srsr =
-sL that -he s-1ri witch ttsT carry f-r
nsl@s aus c~sr 49, o-esa te-T rlsr 49, t-ss
-ut = reach ~ tha mariners hesr.rF fs~
sls,-rusrd 90 even = fsw arn1ra8 tset ef
s,rr.. -as7 pasY w1fh 81 - is we're ,oot-
a.. xicx s hsrs snd threw N taers. snT-
wheTs hut 81 sts rsrtn@rs wzztlng sar -
fr-~sdeucs Journal