Scientific American
120
AUGUST
Indeed, they were never intended for the finest
THE ASTROLABE OF REGIO MONTANUS.
urements_
BY CHARLES Aa BRABSLER.
Since they
meas·
were light and easily carried
word f o r
Above the planisphere lies the neatly cut out and
The subject of our present article, which we shall
about, being from twenty to thirty centimeters in di­
decorated
endeavor to describe as well as illustrate, is one of
ameter, they were peculiarly adapted for seamen and
the
those intensely interesting instruments
used by
our
travelers.
ecliptic
forefathers
the
and
for
taking
the
altitude
of
sun
A
clever
observer
such
as
Regiomontanus
might
1905.
planum, signifying a plane).
sphere, and
a
12,
"rete"
carrying
constellations
and
of
the
upon its
ecliptic.
circular
The
interior
pole
of
the
the positions of some of the stars are
also given.
It is tb.e astrolabe of Regiomontanus,
obtain very exact measurements with a carefully-con­
and it may still be seen in the Germanic Museum at
structed astrolabe such as the one we show in the cut.
the'
Nuremberg.
The
pointed ends of which serve as indicators for reading
stars at sea.
Who was this Regiomontanus?
Johannes
astrolabe
was
a
sort
of
universal
instrument.
Turning upon the axis of the whole we finally find
diopter rule, called also the "Alhidad rule," the
Muller by name, he was born at Konigsberg in 1436,
Not only could the height of a star above the horizon
off the degrees on the outer circle.
and he became an astronomer and mathematician of
be measured by it and its distance from the zenith,
from the ends and approaching the center we see the
repute, in fact one of the greatest astrono·
little sighting boards with their holes for
mers of the time, and like the great men
vision.
of the day he affected the name of his native
time
city,
up
conferring
thereby
fame
upon
his
birthplace, and assumed, therefore, the ap­
Regio.l1wntanus,
pellation
meaning
the
must
proceed
as
follows:
Hang
astrolabe so that the plane of the
coincides exactly with
the sun's rays.
Then,
the plane
of
looking through the
two holes in the diopter rule, turn it until
In connection with Bernhard Walther he
the sun can be seen.
built, in 1472, the first German observatory,
exact
If now we desire to find the local
we
mater
a
Konigsberger.
where he
Slightly removed
conducted
observations
a
series
with
the
of
the
most
beautiful
in degrees at the point of the diopter near­
in­
est the eye.
struments of his own invention and mal{e,
to which this astrolabe also belonged.
Upon the extreme cir­
cle the height of the sun may now be read
Now look up in the tables the position of
A
the sun,
number of instruments of the kind that were
the sun's longitude for
this day
in the ecliptic, and, by turning the "rete,"
employed upon shipboard sprang from his
bring the point on the ecliptic of the sun
fertile
given
brain;
and
it
is
certain
that
Co­
for
this
day
into
coincidence
with
lumbus made use of the astronomical tables,
the height of the sun as measured by the
compiled by Regiomontanus, for the deter­
diopter
mination of his whereabouts during his voy­
pointer on the "rete" will now indicate a
rule on the outer scale.
A special
ages and they must have played an import­
figure engraved upon the disk, which will
ant part in the later discoveries of the bold
correspond with the sun's time at the mo­
Genoese_
ment of the observation.
It was Regiomontanus, too, who
first studied
the
distances
and
motion
of
The astrolabe in
its positive form was invented by Hipparch­
the comets.
us in the second century before Christ and
Before the telescope was discovered, and
until
the
beginning of the eighteenth
cen­
it only came into use in 1610, all the practi­
tury it was occasionally used, even though
cal astronomers busied themselves exclusive­
it did not give very exact results.
ly with measurements.
To-day the telescope
... ....
and the measuring instrument are combined
A SAFETY BUFFER FOR AUTOMOBILES.
and in this form the most exact observations
Collisions by an automobile, either with
of the stars are made possible; then the so­
stationary or moving objects, nearly always
called
diopters
were
employed
had to be pointed at the stars.
and
they
result in a certain amount of damage being
These were
inflicted upon the motor vehicle.
either tubes having small openings in either
As a rule
it is the front lamps, mudguards, and, occa-
end through which one could see the star,
Sionally,
ASTROLABE OF REGIOMONTANUS,
or rulers of wood or metal, that carried at
the
front
wheels
which
SUffer.
With the object of minimizing this danger,
their lower end a perforated board' and at the upper
but also many measurements, particularly the position
and also for protecting the obstacles with which the
end a similar board used as a sight.
of the sun, from which the local time and also the
car happens to collide, a novel safety buffer has been
sidereal time
introduced by the Simms Motor Manufacturing Com­
This method of 'observation, far from complete, re­
quired
large
and
carefully-divided
circles,
that
is,
astrolabe
could
be obtained.
When in
was suspended by the ring at the
use the
top or
pany, of London.
quarter circles or quadrants wherewith the height of
held freely in the hand so that the white line we see
the stars above the horizon or the distance between
drawn across the face of the disk should fall exactly
rim
two stars
upon the horizon and in that way form the artificial
members
could
be measured;
for
the
larger
these
quadrants the farther apart were the divisions repre­
horizon ,
senting degrees and as a consequence the more exactly
dicular to it.
was
perfect suspension
the
operator enabled
to read
them
off.
Tycho
Brahe, the great Danish astronomer of the sixteenth
the
vertical
lines
should
be
perpen­
From this it is easy to see that an im­
of the instrument would lead t o
grave faults i n the calculations.
eentury, had worked with one of these large measur­
ing instruments.
while
According to Biirgel he had a huge
segments
are engraved, was made of metal;
so also were all
attached
of the chassis
either
to
the
front
of the automobile.
or
side
To this
rim is fixed a short length of pneumatic cushion, fully
inflated.
Being placed well in advance of the front
of the vehicle, the lamps, mudguards, and wheels are
adequately
The large disk, upon which the divisions of degrees
As will be seen from the accom­
panying illustration, the device consists of two short
protected,
and
the curved nature
of
the
buffer tends to transform the impact into a glancing
blow.
OWing to the bracket carrying the buffer being
quadrant let into a wall, called a wall quadrant, with
the other parts most carefully worked out of metal.
of stout construction and fashioned in the form of
a radius of more than three meters; the whole circuit
Mater is the name given to the large disk divided into
spring, there is little possibility of the buffer collaps­
of this immense instrument was nigh
degreE'�.
ing or buckling by the force of the impact with another
meters.
He was successful in
on to twenty
obtaining
very exact
Inside of this is set a second metal plate,
the so-called planisphere, and we can recognize it by
results with this. The astroblades were, however, much
the engraved net work.
small"!r, and also the results were greatly inferior to
degree-divisions
those obtained with the huge quadrants and octants.
plane surface,
Car Equipped with Buffer Striking
a
of
the
This net work comprises the
heavens carried
hence the
name
out
upon
a
(sphaera, the Latin
Delivery Tricycle.
A NOVEL l'NEUMATIC SAFETY BUFFER FOR AUTOMOBILES.
a
object.
The device has been subjected to several tests when
fitted to a 20-horse-power car.
The
working of
the
buffer is well shown in the accompanying illustration.
A Near View of the Buffer.