The Sleepwalkers (134 page)

It
will
be
remembered
that
Canon
Koppernigk
recorded
only
twenty-seven
observations
of
his
own
in
the
whole
Book
of
Revolutions
;
for
the
rest
he
relied
on
the
data
of
Hipparchus,
Ptolemy
and
others.
This
had
been
the
general
practice
up
to
Tycho.
It
was
taken
for
granted
that
planetary
tables
must
be
exact,
as
far
as
possible,
for
calendrical
and
navigational
purposes;
but
apart
from
the
limited
data
required
for
these
practical
reasons,
the
necessity
for
precision
was
not
at
all
realized.
This
attitude,
which
is
all
but
incomprehensible
to
the
modern
mind,
was
partly
due
to
the
Aristotelian
tradition
with
its
emphasis
on
qualities
instead
of
quantitative
measurement;
within
that
mental
framework
only
a
crank
could
be
interested
in
precision
for
precision's
sake.
Besides,
and
more
specifically,
a
geometry
of
the
skies
consisting
of
cycles
and
epicycles
did
not
require
a
great
many,
or
even
very
precise,
observational
data,
for
the
simple
reason
that
a
circle
is
defined
when
its
centre
and
a
single
point
of
its
circumference
are
known,
or,
if
the
centre
is
unknown,
by
three
points
of
its
circumference
alone.
Hence
it
was,
by
and
large,
sufficient
to
determine
the
positions
of
a
planet
at
a
few
characteristic
points
of
its
orbit,
and
then
to
arrange
one's
epicycles
and
deferents
in
the
way
most
favourable
to
"save
the
phenomena".
If
one
projects
one's
mind
back
to
the
other
side
of
the
watershed,
Tycho's
devotion
to
measurements,
to
fractions
of
minutes
of
arc,
appears
as
highly
original.
No
wonder
that
Kepler
called
him
the
Phoenix
of
Astronomy.

On
the
other
hand,
if
Tycho
was
ahead
of
his
time,
he
was
only
a
step
ahead
of
Kepler.
We
have
seen
how
Kepler
was
pining
for
Tycho's
observations,
for
precise
data
on
mean
distances
and
eccentricities.
A
century
earlier,
Kepler
would
probably
have
rested
on
the
laurels
of
his
solution
of
the
cosmic
mystery
without
bothering
about
those
small
disagreements
with
observed
facts;
but
this
metaphysical
cavalier-attitude
towards
facts
was
on
the
wane
among
the
advanced
minds
of
the
time.
Ocean
navigation,
the
increasing
precision
of
magnetic
compasses
and
clocks,
and
the
general
progress
in
technology
created
a
new
climate
of
respect
for
hard
fact
and
exact
measurement.
Thus,
for
instance,
the
debate
between
the
Copernican
and
Ptolemaic
systems
was
no
longer
pursued
by
theoretical
arguments
alone;
both
Kepler
and
Tycho
independently
decided
to
let
experiment
be
the
arbiter,
and
tried
to
determine
by
measurement
whether
a
stellar
parallax
existed
or
not.

One
of
the
reasons
for
Tycho's
quest
for
precision
was,
in
fact,
his
desire
to
check
the
validity
of
the
Copernican
system.
But
this
was
perhaps
rather
the
rationalization
of
a
deeper
urge.
Meticulous
patience,
precision
for
precision's
sake
was
for
him
a
form
of
worship.
His
first
great
experience
had
been
the
awestricken
realization
that
astronomic
events
could
be
exactly
predicted;
his
second
was
of
the
opposite
kind,
On
17
August,
1563,
at
the
age
of
seventeen,
while
Vedel
was
asleep,
he
noticed
that
Saturn
and
Jupiter
were
so
close
together
as
to
be
almost
indistinguishable.
He
looked
up
his
planetary
tables
and
discovered
that
the
Alphonsine
tables
were
a
whole
month
in
error
regarding
this
event,
and
the
Copernican
tables
by
several
days.
This
was
an
intolerable
and
shocking
state
of
affairs.
If
the
stargazers,
of
whose
low
company
his
family
so
disapproved,
could
not
do
better,
let
a
Danish
nobleman
show
them
how
a
proper
job
is
done.

And
show them he did, by methods and gadgets the like of which the world
had never seen.

2.
The New Star

At
the
age
of
twenty-six,
Tycho
considered
his
education
complete,
and
returned
to
Denmark.
For
the
next
five
years,
till
1575,
he
lived
first
on
the
family
estate
at
Knudstrup,
then
with
an
uncle,
Steen
Bille,
the
only
one
in
the
family
who
approved
of
Tycho's
perverse
hobby.
Steen
had
founded
the
first
paper
mill
and
glassworks
in
Denmark,
and
dabbled
a
lot
in
alchemy
in
which
Tycho
assisted
him.