Evening star., 1953-04-03
lncus, Locking Wheels,
Built Fine Highways
Luid 10000 Miles Of Paving,
Dug Tunnels, Hung Bridges
By Thomos R. Henry

Greatest engineering feat of pre-
Columbian America was the 10000 mile
paved highway of the Inca empire.
It stretched from the jungles OF
Ecuador along the desert seacoast of
Peru and crossed parts of the Andes
at elevations of more than 5000 feet.
Inca engineers dug tunnels through
solid rock and built suspension bridges
over great chaSms.
Much Of this road is in use today. It
will be studied intensively for the next
two years by DR.. Victor Won Hagen of the
American Geographical Society. This
highway was built during the 18th CEN
tury. At that time. there was nothing
comparable in the world. The great
Roman road system Of Europe largely
had disappeared.
The Inca system compares favorably
with the Roman system despite the fact
that these Indians had no knowledge of
wheeled vehicles.
Exploration Planned.
DR.. Won Hagen and his associates
plan to explore about 1000 miles of the
highway network from Quito, Ecuador.
TO Lake T1ticaca in the Bolivian Andes.
They will make an intensive study not
only OF the highway network itself and
the construction methods of the Inca
engineers. but of the whole way of life
that developed around it. There were
post houses for royal couriers and viii
lage inns for the accommodation Of
travellers.
It is planned to travel by jeep as
much as possible. Where the terrain
makes automobile travel impossible, the
party Will travel by foot and use llamas
Tor transportation of supplies.
Ihey will carry only dehydrated foods
to tighten the load.
Earth Bombardment.
About $500 Shooting stars" an ho,,r
strike each 120-mile radius of the
earth'S atmosphere.
They leave ionization trails-trails
OF gas atoms Shorn of some of their
outer electrons-approximately 20 miles
'ong before they completely disintegrate.
Ihls is the conclusion of Drs. L. A.
Manning, o. G. Willard, jr., ana A. M.
PETERSEN of Stanford University. lust
reported to the American Geophysical
Union here. Their work was supported
Jointly by the Office of Naval Research
and the Army Signal Corps.
Most Are Invisible,
The 1onization trail of a meteor
sometimes is visible at night AS
shooting star. The greater number
however. are invisible. They do. how
ever, return echoes of high-freuuency
radio signals from attitudes of between
6O and 30 miles where the atmosphere
becomes sufficiently dense so that they
begin to be burned up by friction.
The California investigators carried
out simultaneous radio echo measure
mentS from stations about go miles
apart and were able to pick up some of
the meteor trails at their beginnings.
when they are difficult to detect. to
the final disintegration of the minute
pebbles from outer space. The amount
OF lonlzation produced naturally in
creaSes to maximum at the end of
the trail. In this way it was possible
to measure roughly the lengths of the
trails.
The likelihood of picking up any
great number of these meteors. they
point out in their report, Is quite small.
An 1onization trail can be detected
only when it happens to be perpen.
dlcular to the path of the radio signal
sent out. BY calculating the prob.
abilities, they arrived at the estimate
OF $500 an hour within the radius
covered by the signals.