Evening star., 1938-05-04
BY THOMAS r. HENRY.


device that will measure accurate
ly distances of billionth of a cent?
meter and SO incredibly sensitive
that it will detect the precise amount
wall OF stone building is bent by
the sun shining on it was described
to the Acoustical Society OF America,
meeting at the Bureau of Standards
yesterday, by DR.. John c. Hubbard
OF Johns Hopkins University.
1t can measure changes in diameter,
DR.. Hubbard said, of "a few diameters
of an atom" and promises to be a
valuable tool for the most precise
measurements required in industry or
in scientific experiments 1t will give
results much more precise and un-
mistakable than the interferometer,
whose results are due to the inter-
ference with each other of wave
lengths of light and which has been
used in the extraordinarily delicate
experiments made to test the theory
of relativity.
1t will be useful, DR.. Hubbard said.
in measuring the precise expansion
OF fine wires at various degrees of
temperature, the diameters Of glass
fibers and the estimation of the moist
ure content Of thin. solid films. The
device is a piezoelectric quartz crys-
tai which has the property of vi
brating to a very narrow band of wave
lengths and setting up an electric
current which will operate an indi-
eating device. Another form of the
same device is used by radio broad
casting stations to keep the wave
lengths within prescribed channels.
"ArtificiaI Milk" Made.
1t is so delicate, DR. Hubbard said,
laboratory it cannot be used when
cadet drill is in progress on the
campus because of the vibrations
which are set up by the tramping
feet in the ground, which are trans
mitted to the walls of the building.
There is a notable response when
class meets in the room above be-
cause Of the almost infinitely minute
degree to which the weight of the
students ber.Gs the walls.
With very similar quartz vibrators,
Dr. Hubbard revealed after the meet
ing. method has been devised at
Johns Hopkins of making an emul-
sion Of water and olive oil which is
essentially an artificial milk" which
can be injected into the veins of new
born babies too weak TO nurse, and
in this way some infants can be saved
who otherwise would perish in few
hours.
The crystal is set in vibration by
radio impulses while 1t is immersed
in a pan OF the two liquids. 1t sets
up a supersonic vibration in the liquid
itself, the extremely short, inaudible
sound waves moving in every direc-
ton and thoroughly mixing the mole
cules of the two substances.
The society went on record yester-
day in an official statement defining
noise as any unWanted sound"
There is altogether too much of it,
the society believes.
Physiological studies.' said the
statement, show that heart action.
breathing and digestion are. unfayor
ably affected by noise. Office workers
note an increased nervous tension and
reduced efficiency when they are sub
jected to the continuous disturbance
of typewriters and other machines.
In an experiment extending over
year it was found that one group OF
employees equipped with ear defen-
ders' was per cent more efficient in
production than similar group with
out the protective device"
Autos Big Offenders.
A survey of noises in New York
City. the report continued. showed that
SO per cent of it was due to motor traf-
fic, with its horns, cut-outS, grinding
brakes. traffic whistles. etc. About Is
per cent was due to the street cars,
subway and elevated. Radios in homes
and stores accounted for II per cent
of the total noise.
Slightly less than 10 per cent was
due to collections of ashes and garb-
age and deliveries of milk. ice. etc.
Whistles and bells of locomotives. fire
trucks, steamers and tugs accounted
for 8 per cent Pneumatic drills and