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describe anomalies in it, such as occur around iron ore deposits. As far as
we know, the lines have no equivalent in reality, and if they did, they
would vary all over the place as the earth's field changes, anyway.'" Do
pigeons then follow some maplike structure in the earth's field itself, a
grid like that described by dowsers and geomancers since ancient times,
something we can't find today even with our SQUID? Some migrating
birds make a dogleg to the east in their north-south flyway, sailing out
of sight of land over Lake Superior. Do they go out of their way to avoid
being disoriented by iron ore deposits in the Mesabi Range? We can
suspect, but we don't yet know.
To most people, of course, the most interesting questions concern
themselves. Do we, too, have compasses in our heads?
On June 29, 1979, R. Robin Baker, a young University of Man-
chester researcher into bionavigation, led a group of high school students
into a bus at Barnard Castle, near Leeds, England. Baker blindfolded
and earmuffed them, then gave them all headbands. Half of the head-
gear contained magnets and half contained brass bars that their wearers
thought were magnets. As the volunteers leaned back to concentrate,
Baker wove a mazelike course through the town's tangled streets, then
traveled a straight highway to the southwest. After a few miles the coach
stopped while the students wrote on cards an estimate of the compass
direction toward the school. Then the driver turned through 135 degrees
and continued east to a spot southeast of the school, where the students
again estimated their direction. When the cards were analyzed, it turned
out that the persons with brass bars by their heads had been able to sense
the proper heading quite reliably, while those wearing magnets had not.
Gould and his Princeton co-worker K. P. Able recently tried to repli-
cate Baker's experiment but failed. However, Baker's review of the at-
tempt suggested that the volunteers' directional sense may have been
thrown off by magnetic storms, weak magnetic gradients inside the bus,
and/or the greater electromagnetic contamination of Princeton compared
with rural England. Baker and co-worker Janice Mather have recently
devised a simpler test method. In the middle of a specially built, light-
tight wooden hut free of magnetic interference, the subject is blind-
folded, earmuffed, and seated on a friction-free swivel chair. After being
turned around several times, the subject must estimate his or her com-
pass heading as before. With statistically consistent success in more than
150 persons, Baker believes he has proven the existence of a human
magnetic sense.
Oddly enough, he finds that as long as people can't feel the sun or
sense some other obvious cue, they can judge direction better with blind-