Evening star., 1932-04-30
COSM|C RAYS MARK
/ ARRIVALS ON TAPE
/ IN CAPITAL TESTS
Plunge at Incredible Speed
Through Covering of
Record Chamber.
ABOUT DOZEN STRIKE
BODY EVERY SECOND
Average of Seven Per Cubic Cent?
meter Every 1000 Seconds Re-
ported at Standards Bureau.
BY THOMAS r. HENRY.

Cosmic rays plunging with incredible
power and speed through a thick slate
roof and wooden floor, are registering
their arrival on a ticker tape at the Bu-
reau of Standards today.
A counting machine for these myste-
riouS projectileS bombarding the face
of the earth from outer space was set
up for the meeting of the American
Physical Society by Drs. j. c. Street
and Thomas H. Johnson of the Bartol
Research Foundation, who reported the
actual counts made.
The instrument shows that the rays
are quite rare, seven on the average
striking each square centimeter of the
earth every 1000 seconds A total of
about a dozen pass through the average
human body from all directions every
second. The device consists of three
Geiger-M Muller counters, arranged YER
tically, one above the other. The
counter is hollow tube through which
passes wire carrying the highest pos
1tive charge of electricity possible with
out causing discharge.
Ray Causes Discharge.
When a cosmic ray enters the cham
ber it "ionizes" some of the atoms of
the atmosphere around the wire. This
upsets momentarily the balance of posi-
tive and negative electricity and causes
the wire to discharge. This, in turn,
can be registered by key striking the
ticker tape. But anything-ultra-vi violet
rays, heat rays, etc.-which got into the
tube might cause such discharges. The
heat of a lighted match across the room
will cause it to go craZy"-as one Of
the experimenterS described 1t.
But these tubes are so wired that a
discharge is registered only if a dis
charge takes place simultaneously in all
three. Nothing could do this but a
coSmic ray. 1t must penetrate five metal
walls and about a foot of gas-and In
practically mo time at all"-in order
to produce simultaneous ionization In
all three tubes and set the three wires
to discharging at once. Any other form
of radiation would be stopped long be-
fore it got over these hurdles.
The rays are believed to come from
outer space. The most powerful of them
will penetrate 200 feet Of water or six
feet of lead The slate roof Of the
Bureau of Standards Building where the
mechanism was set up and the wooden
floor above the demonstration room
were no obstacles. As many marks were
made on the ticker as if the apparatus
had been set up under the open sky.
Most of them come from a vertical di-
rection. Very raTRly one enters the
tubes when they aye placed in q hori-
zontal plane. The distribution In time
seems quite irregular. Sometimes the
tape will run for almost half hour
without a record. Usually they come at
O rate of about five every two minutes
Tells Of Nitrogen Trap.
z@v-@al "
TO the physicists by DR.. w. F. G: Swami
of the Franklin Institute. The trap
was an iron tube, Is feet long, filled
with nitrogen under high pressure. It
was determined from calculation that
If a cosnic ray entered this tube 1t
would raise havoc with the nitrogen
atoms by knocking of outer electrons.
For every centimeter the ray Travelled
through the gas, DR.. Swami calculated
il would hit about 100 atomic systems
converting each of them into ions
by taking of an electron. Through the
entire IS feet it would produce approx
tmately 40,000,000 CT these ions. Such
a sudden and enormous increase in the
ion content of the nitrogen could be de-
tected by physical measurement.
DR.. Swami also calculated that q
cosmic ray should pass through the
tube about four times an hour. Inc
experiment showed that this was just
about what happened. Four times eacr
hour there would be this enormous ION
spurt which, since it corresponded te
the calculated effect, could only be at
tributed to a single one of these myste-
riolls visitors having entered the trap.
The cosmic rays are made TO take
their own photographs-or rather tne
photographs of the tracks they are 1oi,
iowirg-by another device developed al
the Bartol Foundation Three OF these
devices. described as "clcud expansion
chambers" are being constructed fol
studying cosmic ray tracks over ex'
tended lengths of their paths.
Bares Effects of Dust.
Measurement of the comparative
effects of dust in the atmosphere ant
humidity on visibility effects IN New
York City was reported by DR.. Morgan
T. Riley of the National conference
Beard on Sanitation. He found ina
10000 dust particles per cubic loot pal
anced a 10 per cent increase IN relative
humidity. On more than half the days
he found, dust was more important II
decreasing the visibility, on 81 per cen
of the days humidity was Of the creates
Importance and one per cent OF thu
days the effect was equal. These values
he suggested. can be made the measure
of the success of an anti-smoke cam
psign.
INDEMNITY COMPANY SUIT