3rd c. B.C. Archives - Kotsanas Museum

Archimede’s burning mirrors

admino — Tue, 09 Apr 2024 10:10:29 +0000

It is a hypothetical reconstruction of the renowned burning mirrors of Archimedes. Several ancient Greek writers, including Archimedes, had written books “on burning mirrors”, but none of them have survived. Some medieval writers describe the burning of the Roman fleet by Archimedes using such mirrors, though it is not mentioned by ancient writers. One of them, Ioannis Tzetzes (1110-1180 A.D.) describes the burning of ships, from a distance within an arrow’s range, with the help of large hexagonal mirrors invented by Archimedes. He also mentions that these large hexagonal mirrors consisted of smaller mirrors, adjusted to the main one by means of blades and joints. This remarkable description indicates an adjustable mirror with variable focus. Although the alleged burning of ships is considered a myth, it would be quite possible to set moving ships on fire using large mirrors with adjustable focus. The reconstructed mirrors, using the right placement of pulleys (or gears alternatively) and the easy rotation of a single rope, follow an adjustable parabolic path, constantly changing its focus, according to the operator’s will. Archimedes had all the necessary knowledge in Mathematics and Engineering, as well as the technological skills in order to construct them.

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The “anaphoric” clock

admino — Tue, 09 Apr 2024 10:10:05 +0000

It was a brilliant hydraulic clock which indicated, with accuracy, the 365 different hours of the year. A cam disc – on which a drawing represented
the sky and the zodiac cycle – rotated behind a bronze grid. The grid consisted of 7 homocentric circles defining the month intervals and 24 curved rods defining the hours according to the “hour – month” diagram (“analemma”). The rotation of the disc was achieved through a pulley and a flexible chain
with a counterweight and a weight-float which was lowered or lifted through the isochronous (=equal time) descent or ascent of the water level. This isochronous descent or ascent was ensured by the isochronous water outflow
through a self-regulated controller of the constant level of the Ktesibios type.
Every day a pointer was placed successively on the corresponding one of the 365 holes of the disc periphery, which defined the days of the zodiac year, and marked the 12-day and 12-night non-isochronous hours according to the season.

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The automatic goblet of Philon

admino — Tue, 09 Apr 2024 10:12:31 +0000

It was an invention of Philon of Byzantium which always kept a goblet of wine full, regardless of the quantity removed. It consisted of an air-tight vessel full of wine with a horizontal tube-tap that led to a goblet. The perforated bottom of the goblet led to a hollow base (horizontal piping with a vertical tube that reached the height of the goblet). A smaller tube that started from the top of the air-tight vessel penetrated its bottom and entered the vertical tube of the hollow base in a depth equivalent to the desired level of the wine in the goblet. The level of the wine in the vertical tube of the hollow base fell after the removal of a certain quantity of wine from the goblet, thus, allowing the entrance of air through the smaller tube in the air-tight vessel. This led to the flow of wine towards the goblet and to the increase of its level in the hollow base. When the level of the wine reached the mouth of the smaller tube of the vessel it created vacuum and the flow stopped.

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The automatic servant of Philon

admino — Tue, 09 Apr 2024 10:07:06 +0000

This was a humanoid robot in the form of a female servant (life-size) which in her right hand held a jug of wine. When the visitor placed a cup in the palm of her left hand, she automatically poured wine, initially, and then she poured water into the cup mixing it when desired. Inside the servant, there were two airtight containers with wine and water, respectively. At their bottom there were two tubes leading their content through her right hand to the lip of the wine jug. Two air pipes started at the top of the containers, went through their bottom and led curved into her stomach. Her left arm was connected, through the articulation, to her shoulders; while a helical rod (spring) that was positioned in extension of the restraining rod raised it. Two pipes started at the same point (joint) and came down penetrating and freeing the curved perforated ends of the air pipes. The pipes of the joint had two holes at their ends, with the hole that communicated with the wine container preceding that which communicated with the water container. When the cup was placed into the servant’s palm, her left hand came down and the tubes of the joint lifted. The hole in one pipe was aligned with the air pipe of the wine container, air entered the container and wine flowed from the tube into the cup. When the cup of wine was half- full, the hand (due to weight) descended further, the passage of the air pipe of wine was obstructed and the flow stopped. At the same time the other tube was aligned with the air pipe of the water container and it began to flow, thus, diluting the wine. When the cup was full, the hand (due to weight) descended further, the passage of the air pipe with water was obstructed and the flow stopped. Also, if the cup was removed at any moment, the left hand rose, the tubes of the joint descended, cutting off the air pipes, creating vacuum in the containers and stopping the liquid flow. The servant then filled the visitor’s cup with wine or diluted with water of desired quantity depending on the time it was pulled from her palm.

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The hydraulic automaton of Pan and of the thirsty dragon or deer

admino — Tue, 09 Apr 2024 10:12:23 +0000

It was a conception of Philon of Byzantium depicting a dragon or a deer that drank water with great hunger and roared only when Pan turned away from it. When Pan turned, the dragon relaxed. The theme was repeated continuously. For the operation of the automaton, water from a spring was driven inside the airtight intermediate container, forcing air to leave towards the built-in tube of the dragon or the deer giving a roaring impression. Then, when the water level exceeded the axial siphon, it emptied through it to the lower container, therefore, because of the vacuum created by the emptying of the container, the tube incorporated in the deer sipped water and air giving the drinking impression. If Pan turned to the deer, the water from the spring was driven by the rotating horizontal pipe directly into the lower container, the phenomenon ceased and the water level in the large krater (bowl) rose.

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The hydraulic automaton of the “chirping birds” and of the “returning owl”

admino — Tue, 09 Apr 2024 10:07:30 +0000

It was a conception of Philon of Byzantium (which was improved by Heron of Alexandria) depicting birds chirping, when an owl turned away from them and they stopped frightened, when it turned towards them. Automatically, the theme was repeated continuously. For the operation of the automaton, water from a spring was driven inside the upper airtight container forcing the air to leave through a pipe. Because the pipe led to water, the vibrating wavelength produced a chirp with notes of different frequency. Then, when the water level exceeded the curved siphon of the container, it emptied through it to the intermediate container, diverting a yoke to its side. This forced the built-in rotating shaft supporting the owl to turn towards the birds that then stopped chirping. When the water level exceeded the axial siphon of the intermediate container, it emptied through to the lower container, diverting the yoke towards its counterweight, which caused the owl to turn away from the birds that then began to sing again, etc.

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The hydraulic clock of Archimedes

admino — Tue, 09 Apr 2024 10:12:39 +0000

It was a complex hydraulic clock with many automatically moving objects. It consisted of the central storage container which supplied the water. The water went through a smaller container which ensured the stability of the water level (with a conical valve on a float), leading to the outflow nozzle. The supply of the flow was regulated depending on the date, turning the nozzle on a calibrated semicircular disc (so that the hypsometric difference of the nozzle outflow hole and the level of water were altered, consequently, altering the time duration of the hour on the particular day). On the two columns of its façade, two moving rings (and two statuettes) indicated the hours that had been covered and the hours which remained respectively. On each hour, the pupils of the human eyes on a mask changed colour and a spherule fell into another container from the automatic opening of a crow’s beak, with a bang. Simultaneously, the water fell into a volumetric container which, on the hour, was automatically reversed and two small snakes slid towards the birds on the tree that cried out frightened.

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The hydraulic clock of Ktesibios

admino — Tue, 09 Apr 2024 10:07:54 +0000

It was a marvel of automation, since the clock was able to operate continuously, without human intervention, indicating the 365 hour-days of the year (of altering day time hour duration). The water from a spring supplied, through a spillway, the upper bronze container. This, in turn, supplied the smaller intermediate container which was a constant level controller through a system it contained (a conical valve on the float to interrupt the flow). Then a dripper supplied the tall bronze container, drop by drop, with a constant water supply. With the rising of water there in the float rose and, through a rod, a statuette with a pointer rose at the same pace. The pointer indicated the hour of 24h on a rotating drum containing a trace of hours of day and night depending on the date. At the end of the 24 hours, the water exceeded the side-built siphon and drained rapidly. On the descent of the float an ingenius drive system was activated in the ratio of 1 in 365 (which consisted of a toothed ruler, a pawl, two gears and a worm gear) that ensured the rotation of the drum calibrated in 1/365 of its circumference as the pointer of the statuette now indicated the exact time of the next day.

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The ingenius wine-jug of Philon

admino — Tue, 09 Apr 2024 10:06:25 +0000

It was a jug –conception of Philon of Byzantium– from which water, wine or watered-wine, depending on the will of the cupbearer, was poured automatically. It consisted of a vertical diaphragm that separated the jug into the compartments of water and wine, and the outlet fluid pipes which, however, were found one inside the other so that outside the jug they appeared as one. The jug had an airtight lid which made it impossible for the fluids to flow at its inversion, because of the vacuum that was created by the inability to substitute the outlet fluids with air. Two tubes began in the middle of the jug (the one communicated with the water compartment and the other with the wine compartment) and reached the neck so that they formed its handle. At the sides of the tubes there were air holes which the cupbearer covered with his finger. With the combinational disclosure of the air hole of the water compartment, wine compartment or even the two simultaneously, the cupbearer allowed the incoming air into the corresponding compartments and the flow of water, wine or watered-wine, according to the wish of the visitor.

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The planetarium of Archimedes

admino — Tue, 09 Apr 2024 10:11:34 +0000

This is a remarkable device which simulates automatically the complex movements of the sun, the moon and the planets known in antiquity, as they appear from any point on earth. It constitutes the most complex mechanism of antiquity. It was a remarkable invention as attested by the relevant reports of ancient sources. According to Cicero (1st c. A.D.), it was the only piece of the spoils that general Marcellus kept for himself after the fall of Syracuse. Suggested reconstruction: With every manual turn of the sphere, the central inner disc rotates isochronously through suitable cogwheels, having a transmission ratio 1:365,25 (3651/4), which was the assumed year duration at the time. Going further, the differing periodicity of the above celestial bodies is achieved with astonishing accuracy through a complex system of cogwheels, as well as the acceleration, deceleration and reverse movement. The sun and its inner planets (Mercury and Aphrodite-Venus), according to the geocentric system, are equipped with a suitable arrangement of cogwheels and jointed bars with slots, to accelerate their apparent movements (angular velocities and bidirectional movements) perfoming a full rotation throughout the year. The outer planets (Mars, Jupiter and Cronus-Saturn), on the contrary, carry a separate pair of eccentric cogwheels with a brilliant pin and slot system for their periodic (2 years and 10 months, 12 years and 30 years respectively) and bidirectional movements. The moon carries the cog-wheel arrangement corresponding to the mechanism of Antikythera, in order to effect its periodicity (27 and 1/3 days) and angular velocity. Its phases are shown through its simultaneous rotation around its axis, via a pair of vertical cogwheels and a leather string inside its supporting tubelet.

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