New-York tribune., 1920-02-01
Scientist Explains
Why One Is Led to
Sing in Bathroom
Running Water Strikes Note
and Voice Sounds Reso-
nant, While Furniture i'm
Bedroom Tends to Deaden
Foreign Press Bnyenu

NeU fork 1 r1bune
LONDON, Jan. 5.-"Sounds7 Of the
Town" was the subject of the third of
a series of Christmas lectures by
Professor w. H. Bragg q, the Royal
Institution Of "The World of Sound"
According to an account in "the Times"
Professor Bragg delighted his Juvenile
audience by his experiments in ex-
planation Of familiar noises in the
house-thc roar of the wind in the
chimney, the drip of water in the bath,
the echoings of an empty room, the
singing of the kettle, and the creakings
that are heard from the house is still
at night.
"Why do so many people sing in the
bathroom ?" asked the Professor, and
the girls and boys broke out into
laughter, remembering the impulse
that selzes them to break out into song
when they are having bath. The
professor explained that the note is
struck for them by the running water.
He also pointed out that, while the
voice sounds resonantly in the bath
room, it is not half so fne or inspir-
ing when song is continued in the
dressing room.
The reason is that the furniture of
the dressing room tends to deaden the
reverberations. Professor Bragg then
gave illustrations of the rise and fall
Of the pitch of the noises caused by
the dropping of little indlarubber
ball into a bowl Of water
Why the Kettle Sings
When the ball was given an irregu-
lar surface by dirt or grease it "burst"
the water, and thereby caused a loud
"plap," but when the ball was rubbed
quite clean and dry it fell noiselessly,
because the water Tapped around its
even surface.
The explanation given of the singing
OF the kettle was that the bubbles Of
steam formed at the bottom. nearest to
the fame, tried to get to the top, and
coming into contact with water of a
lower temperature fell back again with
sounds like tiny hammer strokes on
something solid. The roaring in the
chimney is due to the vibrations of
the air caused by the heat of the fire.
In illustration Of this the professor
produced strange roaring noises from
two drum pipes, one eight feet and one
twenty feet long, by means of a gas
burner placed underneath Those eerie
creaks and clicks heard at night are,
She professor said, simply explained
by changes in tempe rature. Articles
of furniture get warm during the day
and expand, and when the cool of the
Night comes they contract, and in do
ing 80 emit groans as if invisible be-
ings were handling them
Professor Bragg explained why it
was that motor car sounded higher
in pitch coming toward one than when
going away. 1t was possible, he said,
to estimate the speed of the car by the
difference in pitch between the two
sounds, and h could imagine very in
telligent and musical policeman trying
to trap a car that way.
Whispering Gallery of st. Paul's
Professor Bragg told the story of
two great obelisks with curved colossi
erected by q Pharoah in Egypt. One
OF the figures sang when it was shown
open by the first beams Of the morn
ing sun, and pilgrims came from afar
The professor mentioned that he him1
self read an inscription carved on the
obelisk by an ancient visitor, which
ran: 81 came and heard and wondered" "
but q later Pharaoh had the figure re-
paired, and it sang no more. The ex-
panation Of the singing given by sci
ence is that the intense heat of the
Egyptian sun caused Two Of the stones,
which were loose, to CRATE against each
other, and this ceased when, in the
course Of the repairs, the stones were
properly set.
One Of the most famous effects Of
sound IN London, Professor Bragg said,
was the whispering gallerf at St.
PauPs. Words spoken at one end Of
the gallery go right round and are
heard at the other end. a model o.
the gallery was shown. and a gas jet at
one end was made to jump when g
S light noise was made at the other
Wavelets of sound, it was explained,
are reflected along the wall Of the
gallery.
Professor Bragg also told an anus
ing personal experience ne had VIII e in
the service of the Admiralty during the
war. AS an aid in the anti submarine
campaign it Was important to fix exact
ly the sound Of submarine under
water. Sir Richard Pagct, of the
Board of Invention and Research, be
ing an expert musician, was lowered
into the sea. He was brought up hum
min gthe exact note made by passing
submarine.