Maker, Unknown, probably English.
c. 1890. Movement 5h" x 12" dia. / 11"h x 13" over
hexagonal glazed case.
Clock work driven orrery with Earnshaw type, split bi-metallic chronometer detent
escapement with jeweled potence pivot and driven with chain fusee.
Eight day duration. An additional spring barrel drives the orrery with one year duration.
It also serves to eliminate the backlash that would be present in a
mechanism with so many wheels. Subsidiary dial for
the Bisextile, four year
(leap year) cycle. Outer ring with year calendar and zodiacal indicators.
Orrery with two inner planets, Mercury and Venus with rings to indicate each
planet's orbital inclination to the sun. Also a separate tellurian depicting
the Earth and moon system, with moon phases, the moon's orbital inclination
in relation to the ecliptic represented by a ring around the Earth and a
track for the moon to physically rise and fall with respect to the Earth, an
indicator to show where it rises and sets relative to the surface of the
Earth, below a
subsidiary dial for moon's age and phases. The Earth at correct inclination
with dial ring above divided into two twelve hour sectors illustrated with
Roman numerals rotating with the earth. An apparatus connecting the earth to
the Sun to shows the Sun's zenith and declination around the Earth as well
as lines showing the approximate areas of sunrise and sunset in the Northern hemisphere. The entire mechanism
pirouettes upon its central spindle once per year with indicator hand for
outer silvered ring to indicate the position of the sun in the ecliptic as
well as the date, month and zodiac house. All subsidiary dials engraved and
silvered on skeltonized frame with unique upper and lower plates (not
mirrored) held by nine pillars. Total of 45 wheels within the mechanism.
The glazed case has eight sides with metal framing and rests on a painted
wooden base. The base shape and colors suggest an oriental inspiration. The
entire presentation, including the choice of an Earnshaw type chronometer
escapement all contribute to a strong visual impact of complexity. Qualities
I found very attractive.
An overall view showing the large, 12" outer silvered ring engraved with
a calendar containing the months, days and the associated zodiac and their
signs all in Latin. The interior of the base is blue, probably to invoke the
color of the sky.
This device is a combination of a tellurian, which shows only the
Sun/Earth/Moon system and an orrery which includes also other planets.
However it makes no attempt to have a correct scale between the components
of the tellurian and the rest of the orrery making this a hybrid. Of course
if the correct scale were attempted a pleasing representation would be
impossible as the Sun would be huge in comparison to the rest of the
celestial bodies and one could not get the detail of the Earth/Moon system
one enjoys in this model.
A closeup of the Earth, Sun and inner planets of Mercury and Venus.
Notice the apparatus that connects from the top of the sun to a circular
harness around the Earth. This give a depiction of where the Sun is overhead
on the Earth not only at the point where the the harness is supported, but
at any given time by following the harness ring around the surface of the
Earth. A brass ring crowns the Earth with two sets of Roman numerals on each
semi-circle; each I through XII. This ring rotates with the Earth and
indicates the hour of day or night against the pointer just visible in the