New-York tribune., 1919-12-07
Sound Range Finder
One of War Marvels
Is Shown to Public
4
Device, Perfected at Prince.
ton, Enabled Americana to
Locate Hiding Place Of
Gums Ten Miles Away
sreeie, corresncndenee

NOvtSFpVNUSWCS
PRINCETON, N. j., Dec. 6.-Sound
ranging, the process developed here
which enabled American artillery to
erain its guns on invisible German bat
Eeries in action, was given it's first
public demonstration in Palmer ply
Nsics laboratory to-day by Professor
Augustus Trowbridge, head of the
Princeton department Of physics. Pro-
lessor Trowbridge, who was a lieuten-
ant colonel in the army, not only had a
'yreat part in the development Of sound
ranging devices, but was head of the
Sound Ranging Service in France,
where his work was rewarded by the
Distinguished Service Medal, the Brit
ish d. S. o. and the French Cross of
Ehe Legion of Honor.
He declared that sound ranging not
only would play an extremely impor-
sant part in artillery work of future
vars, but would prove of great use in
u number of civilian pursuits.
Distant Guns Located
With the apparatus developed in the
American service the position of gun
N action ten miles distant can be de-
tepmined to within ten yards. During
the final great battles, when American
artillery was most active, half the in
form alton regarding targets came from
The sound rangers.
The French experimental with sound
ranging soon after the war began in
1914 but were unsuccessful The Brit
sh developed it to a certain degree, but
Americans, mostly experts from the
physics department of Princeton, made
crets to the United States government
n 1917.
The apparatus consists mainly of an
electrically operated chronograph. SEN
iitive enough to detect the sound of
runs firing ten miles away. A delicate
line recorder completes the outfit, and
\ trigonometric formula for working
Up the data of the chronograph and
line recorder determines the location
If firing battery
Telling of the sound ranging work in
france, Colonel Trowbridge said the
different sounding stations on the arcs
nan batteries did not require watch
.ng. After setting them up properly
he soldiers returned to their central
stations. The apparatus had to be
suned to "hear" firing to catch the
-eports of the gun discharges, rather
han the whistle Of passing shells or
he explosions of the latter.
This tuning process was reduced to
such q fine point that before the armi-
stice it was actually possible to deter
nine not only the position of the hos
lie guns hut their calibre and their
aiming point
Accurate Results Shown
Colonel Trowbridge exhibited a plate
-scol ding the firing on the morning OF
he armistice on an American sector
During the early forenoon the firing
vas reflected in lines of heavy detona-
lion. At II sharp the lines began, to
weaken; IN ten minutes only an occa-
sional shot was recorded. and by moor
he plate was blank, showing that the
cannonading to whose pitch it had beer
set had entirely ceased.
The sound ranging units organized
Ander Colonel Trowbridges command
consisted of four officers and sixty men
Special training was necessary, the Off
GERS being for the most part scientific
experts. Officers and men both under
vent preliminary training at the
Princeton experiment station before
being sent abroad.
As an actual demonstration of tho
aigh pitch of efficiency to which the
science has been developed. the colone
set up a set used in France and pitch
ing it to the tone of pencil tapping
against a window, found the correct
,lirectio and distance of the source OF
he sound, matter of 55 feet.