New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1873-10-29

s expanaton rests upon the fact that, during the
message of wind between tho observer aud the sound
Nc Instrument, the velocity of this win be
tar,ed az the surface OF the earth, on account OF
stratum immediately above will be retarded by that
below and the obstruction being ioosoned as we
ascend through the strata FROM thls ~ lonoWs that
tho sound wave VIII be deforned and the direction OF
It's normal changed. suppose, Tor example, the
toward the observer IN this ease the retardntOD OF
the sound-wave ABOVE Will be greater IMAM rs te'rua
ton below and the upper part OF the front Oh the Wc
will be thrown backward from the observer, ana Tue
direction OF the phohc wave VIII pe deeIed non No
Garth upward so as TO pass over INC "pierNo,, ~
other hand, II deep river a. wind r. o0whg dr.cty
toward the observer the upper part OF the lOht Oh e
wave will be inclined toward him.
Toe science OF acoustics In regard 70 the phenomena
oped with signal The laws OF It's production,
propagation, reflection and reraciion have been deter
mined with much precision. so that we are enabled IN
most casS9 10 GAdr, I'm tconGt,ops But in case
of loud sounds and those which arc propagated TO
eIeS1 % oscnr,fv sin exists AZ an
illustration OF this Isay mention the frequent occur
war Gen Warren Informs ms tina at the battle OF Seven
Pines in june IsG2 near Richmond Gen. Johnston OF
the Confederate army within three miles OF the
scene of action with force intended attack the flank
OF the Northern forces and although listening atten
lively for the sounds of the commencement OF the en-
lug abont three hours ended without his having heard
the guns. soe Johnstons Report) Another case of a
Caines's Mills june a. 1862 also near Richmond Al
thoughga sharp engagement was in progress within a
his staT were unaware OF the occurrence.
aud when their attention was called TO the feeble
sound thCy had no idea that IL was from ANYTHING more
than skirmish Of little Importance. (Sec Report OF
Committee ON Conduct OF tue WAR;
In third aud perhaps still more remarkable instance
in slrmish bew part OF the second Corps under
Gen Warren and force OF tue enemy the sound OF the
firing heard more distinctly az Gen. Mcade's head
quarters than IL was at the noadlnrltrs OF ne second
Nv the former and the point OF conflict Indeed the
sound appeared 80 near Gen Meades camp that the
Impression was made that the enemy bad gotten be-
tween it and Gen. Watrons command In iact' so many
instances occurred of wrong impressions a 10 direction
and distance derived from the sound of guns that he
reliance came TO be placed on these ndicaons IN me
report of series of experiments made under the drec-
ton OF the Lighthouse Board by Gen. Duane, of tho
Engineer CORPS Is the iolOWlHS Iehalh' me must
perpexng difficulty arises from the fact that the fog
ing In radius from one 10 on" and half miles Thus IN
moving directly from station the sound IA audible for
the distance Of mc Il then lost for alb mt the Same
distance ai,er which II Is again distinctly heard Tor
Aim IN a series Of experiments at which Sir Fred
eric Arrow ana Capt. webb OF the Trinity Board
assisted it found that IN passing IN the roar OF The
opposite side of island IN front of which the fog
signal was placed the sound entirely disappeared hut
by going further Of to the distance OF two or ihree
miles II reappeared ~ full force oven with large
Ain iron, the experiments made under the imne-
dnte direction of the present Chairman Of the Light
AZ" oGCYle1 The Ii.mhouse Engineer and also from
separate experiments made ny Gen. Duane IL appears
that although reflector, IN the focus OF winch steam
whistle ordinary belt - placed, reeniorces the
and indeed the instrument can be as well heard
in st ar tbe distance OF our or five miles in tho
line OF the axis Of the reflector whether the ear lie
cod ne ore OF behind H. Tie only ms pOtcss we can
advance at fOr the explanation OF these remark
able phenomena is that the lateral dWorgcncy of sound
on s Tendency 10 spread aterlly passes from it,
source is much greater tan has been supposed from
pcrmCnts a small scale. Inc lGed we WISH 20 convey
by this h That beau Of sound issuing through on.
ice although at fTet proceeding like beam OF light Ia
paralc rays begins to dVCrgc and 10 spre-d ont
Ia j, co'ici fflsTIn of a sphere and NJ a Sufficient
distance may Include considerable portion 81 s hOr.
Zon BY the application OF thiS bypotnesls 10 tue pccu
iariiics of the topography of a REGION and the position
ri he q IA
Of The phenomena Vi have just mentioned he accounted
for but abnormal elects may be o0,aed in some cases
in actual prCtice
IN critically examining the position Of ;he goundiug
body H. the experiment we htye heuuoncj, II was
found tbat the scas were placed the side OF bank
with large house directly in the rear the roof OF which
would tend to defect upward the sound, 50 as TO pro
duce i'm the dense shadow but on account OF The
ei "a ,,ilr and haf or two miles and at the
distance OF say three miles the sound OF the instrument
was quite loud. doubt not mat on eltlcdi e-iui-
one execution could be referred 10 the same principle
The exception To which l aliude l. expressed Ia
the following remarkable statement OF Cen duane;
'Thc fog signals bayo frequently been heard M DIS
lance of miles and as frequently cannot be heard mt
distance OF two miles ana thls WIN no perceplhe
dIfprence the state OF the atmosphere Tine signal Is
often he ard at greater distance IN one direction, while
another il VIII be scarcely auae AT te ulslauce Oi
ue. Tins Is generally the eilect at the surface, out
cam always be distinctly heard in POgland-l distance
of nine Ite>-duTius heavy northeast sn0w-Storm,
the wind blowing gaze nearly IRON Ioit"hd TOWARD
This is SO abnormal case and contrary to gen
scd under the authority Of the Lighthouse BOaId until
tcould oe VI ried aud more thoroughly examined. In all
date supervision the sound mas always been heard with
two exceptions farther with tie WIND than AGAINST A.
Trse cxccpons were Two cases OF feeble wind, IA
winch the sound heard at greater distance nj right
,nias tn tbr Girccton of the wind IL would appear
bnScycr from an the observations that III normal effect
OF the wind is to diminish the sound III blowing directly
against it. ..o.,,, , ,,,, -, Ga,
atmosphere during northeast storm on our coast
SyhIc appears - To- have direct bearing on the
phcnomtna 10 question. Ii Is this: that while violent
Wind Is blowing from the northeast INTO tne Interior
OF country wind OF equal Intensity is blowing ~ an
opposito direction at tue elevation OF ME OrtWo.
TINS is shown by the RAPIDLY eastwardIy motion OF the
upper Clouds occasionally seen through breaks III tile
lower At. TT. g., .
tou that ON occasion dn 1867 started from ALBANY,
ia the morning Of clear day Wiij Westerly wlhd, on
INV way 20 Boston The weather continued clear aud
within so miles of Boston. We then encountered vo-
lent storm wind and ram winch continued WIN us
uutil We reached inc CITY. On inquiry learned
that the storm had e9minSneed ~ IN Bos,
had been blowing violently toward Albany for 20 hours
Il had reached inwardy more than 81 niles AZ ths
pout IL encountered the west wind and was turned back
above In almost parallel current This IL the general
character OF the northeast storms along our coast ana
very probably give rise 10 abnormal phenomena In re-
gard TO sound which would Otherwise ne le1phcaDle;
Among such the mentioned by Gen. Duane, and
the occurrence must accept as fact, though by no
means a general one applicable to al stations
point Of observation from Cape ElIztbeth, at
the surface of the earth, parallel current
al air Mas flowing with equal velocity in the opposite
direction The eject OF the latter would be to increase
the velocity Of upper part Of the wave Of sound,
and OF the former to diminish It, the result OF the two
Gng TO incline the front Of the wave OF sound toward
he observer and to throw the upper sound down toward
the earth aud thus rendering the distant signal audible
under these conditions when Otherwise IL could not he
heard think probable that the same principle ap
plies in other cases OF the abnormal propagation OF
| sound
Ne NAV mention also in this connection that from the
general fact expressed the divergence OF the rays OF
sound the application OF reflection as means OF re-
enforcing sound of necessity IN considerable de
gree be failure, and also from the feeble effect pro-
duced by simple vibration, such as that from belts
l.l... IL al IN tNnr