Antiquity to the age of modern science,
man has observed and analyzed the
stars to measure and understand
The Musée des Arts et Métiers preserves
several tools in its collection of scientific instruments
that have marked the history and
practice of astronomy.
Prestigious objects that are often exceptionally intricate,
also bear witness to
the fascinating adventure that unites man and
The astrolabe is a calculation and
pedagogical tool of Greek origin
(2nd century BC). It
made it possible to solve astronomic
problems without any calculations. It
identified, for example, the time that the
the sun or the stars would rise or set,
and the sun's height at its
highest point above the horizon, etc.
From the 9th century onward, the astrolabe was commonly used by Arab-Persian astronomers, mainly to accurately determine the precise time to pray.
It was also an instrument that was favored by astrologers throughout the Middle Ages. The astrolabe's popularity only started to decline in the West in the 17th century.
The astrolabe of Arsenius (1530- 1580) exhibited at the Musée des Arts et Métiers is extraordinary due its size.
The diameter of the element called the mater (the receptacle) measures almost 12 inches in diameter.
Here the rete (the movable openwork part that joins the stars and the sun) is divided into months with the signs of the zodiac and it has 43 stars.
An alidade with vanes (a movable ruler for taking precise measurements) sits atop the device. There was no doubt that this instrument was destined to be used in astronomy.
The sundial dates back to
early antiquity when it was
a particularly prestigious
instrument. This instrument, which
has constantly evolved over the centuries,
both in its form, its precision
and its uses, was
mainly intended to
indicate solar time. It
can also give the dates of
the solstices and equinoxes.
From the 17th century, it was used to regulate the clocks, particularly when it was simplified to only indicate midday (the meridian).
During this period, several varieties of luxury sundials were developed, just like this portable sundial made of ivory.
The dial of Benjamin Scott (1688- 1751) dating from 1713, exhibited at the Musée des Arts et Métiers, is distinctive in that it combines two sundials on a single face.
One of the benefits of the double dial was that it was easy to orientate the device in the true North- South direction, simply by rotating it. It functions as a sort of a compass.
Invented in the 18th century by
John Hadley (1682-1744), this
instrument makes it possible to measure,
very precisely, the height
of a star above
the horizon, most notably the
It is a 60° sector equipped with a telescopic sight and two mirrors. One of these mirrors is adjustable.
By taking at least two height measurements and doing a calculation, you can obtain geographical coordinates of your location (longitude and latitude). Provided that you have a correctly set watch.
So in a way the sextant is therefore an ancestor of the GPS. It was essential for maritime navigation and it still is to this day.
French navigators La Pérouse (1741–1788) and Bougainville (1729–1811) are among the most renowned users of this instrument.
The idea of combining
lenses to lengthen
dates back to 1589. The telescope is
undoubtedly an empirically developed
it was sold at the
Galileo perfected the instrument in the summer of 1609, even though he didn't understand how its optics worked.
The discoveries he made with his telescope at the end of that year were published in 1610 in the "Sidereus Nuncius." They turned the world of astronomy upside down.
The four moons orbiting the planet Jupiter were undoubtedly his greatest discovery
Galileo estimated that his telescope magnified 20 times. The magnification effect depends on the diameter of the lens. The largest preserved telescopes in France are in the observatories in Meudon (83 cm) and Nice (76 cm).
Borda's Repeating Circle
The repeating circle, invented by
Borda (1733–1799), is a
graduated circle supported on a base which
can be pointed in any
direction. It is an improved version of the theodolite
(an instrument used for
It was used to measure an angle by taking repeated measurements and it was used initially for geodesic calculations then later in astronomy.
It is equipped with two telescopes with reticle eyepieces used to aim at the sides of the angle to be measured.
Most famously, Borda's repeating circle was used by the astronomers Delambre and Méchain in the 18th century, when they were measuring the meridian of Paris to develop the standard measurement of a meter.
The first orreries were
mechanical instruments used for
demonstration purposes. They were common in
England from the 18th century.
They made it possible to show
students and the public the
the planets around the sun,
taking into account the specific orbital
period of each planet.
Very often they could also show the planets' rotation on their own axis as well as the rotation of their natural satellites. The earth-moon system was particularly well demonstrated.
Many orreries were equipped with a manually operated gear system although some were equipped with a clock system.
The collection of scientific instruments on show at the Musée des Arts et
Métiers makes it possible to retrace certain major advances in astronomy
research. Like the universe it seeks to study, astronomy offers
infinite possibilities, from amateur practices to the advanced
major technologies that define space exploration.
Author: Denis Savoie, Scientific Advisor at the Musée des Arts et Métiers.