Today, a tale of two secret weapons. The University
of Houston's College of Engineering presents this
series about the machines that make our civilization
run, and the people whose ingenuity created them.
The late days of WW-II
finally brought the war to my quiet home in
Minnesota. Since Tokyo was over 6000 miles away,
our mutual slaughter had largely been carried out
in the Pacific Ocean. Then, in January, 1945, we
learned about Japan's secret weapon. She was trying
to ignite our mainland with incendiary bombs.
The bombs drifted over North America, carried by
30-foot-diameter balloons. They were made of fine
Japanese mulberry paper called washi. The bomb was
mounted on a horizontal ring below the balloon,
along with a complex array of small sandbags.
The hydrogen expanded by day, and the balloon rose
until a sensor detected that it was too high. Then
it vented some hydrogen. As the balloon shrank by
night it fell until another sensor dropped
sandbags. Finally, after three such cycles, the
sensor lit a long fuse and vented the remaining
hydrogen. The balloon then landed on American soil,
and, soon after, it exploded.
At first we thought these bombs were being released
by submarines off the West Coast. But the balloons
were too big and far too numerous. They would've
taken too many submarines!
Once we'd found a few sandbags, the Geological
Survey set out to learn where the sand came from.
Sand carries a distinct fingerprint of minerals,
occasional coral fragments, and fossilized diatoms.
(A diatom is the kind of single-celled creature
that makes up algae.) Geological detective work
soon pinned down a region near Tokyo. The bombs
were making an astonishing journey all the way from
Japan -- something no one had thought possible.
We didn't know that Japanese meteorologists had
discovered a jet stream, moving very fast at
altitudes over 30,000 feet. The balloons rode that
jet stream and got here in a scant three days.
So bombs fell harmlessly near Klamath Falls,
Oregon, and Bigelow, Kansas. They fell in remote
corners of Manitoba, Colorado, Texas, and Mexico.
They reached Iowa, North Dakota -- even Michigan.
None landed in St. Paul. But, Oh, Father Christmas!
How this 14-year-old boy longed to see one.
Meanwhile the Japanese press said panic was
gripping America, which was now in flames.
Forensic geologist John McPhee tells the story of
this byroad in military history. It seems that only
one balloon bomb actually killed anyone. It landed
in the Cascade mountains. Five Sunday-school
children and their minister's wife, all on a
fishing trip, found it just before it exploded. It
killed all six.
But I said this was a tale of two secret weapons.
Another balloon bomb ran into an electric line at
the Hanford plant in Washington and cut the power.
For a while, it shut down the production of
plutonium for the atom bomb that would fall on
Nagasaki -- only five months later.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds