Monday, August 14, 2017

Ancient Greece: Philons "Bird and snake"

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This one does not have any practical use. It might just be used for amusement.
Note that you can make the tree invisible, by pressing the invisible-button.

There is water in a reservoir. A bole is mounted on it. It has libs, a bird's nest and birds mounted on it.
A snake is swimming in the water. When water is filled in through the small holes on the right, the water rises and the snake rises, heading towards the birds.
The great bird now defends its little fellows. The rising water moves the bird and swings it's wings.
By sucreasing the water, the snake hides somewhere and the bird, now shure of it's sucess, goes back to the little birds. The presentation is finished. 

Ancient Rome: The water organ of Vitruvius

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According to Vitruvius, Ktesibios was the first to build an organ like this. The water organ of Vitruvius is an enhanced verion, which uses two cylinders.
Organs were used especially in the late Classical Antiquity. We are not quite sure wheter the Romans used Vitruvius' notes, or notes of other mechanics.

The two plungers are moved up and down. If you move a plunger down, air (red) flows through a valve. If you move it up, the valve closes and the air is piped to the hemisphere.
This hemisphere is placed in a reservoir, filled with water. The air is partially compressed, and partially the water is pressed down the hemisphere by the air. The water line in the reservoir rises. One part of the air floats thorugh a pipe on the top of the hemisphere.
There the air floats, passing another valve, in a chamber, whis is connected to the pipes. If a key is pressed, a valve opens. Air floats through a pipe, a tone is created.
The interesting part about this organ is, that water keeps an instant pressure. If air floats out of a pipe, the pressure in the reservoir decreases. The water line sinks and the pressure is restorred to normal.   

Ancient Rome: The Odometer Of Vitruv

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There might have been other Odometers before Vitruv, but only his' survived.
If you pull Vitruvs' wagon, the wheel, as you could imagine, rotates. A finger is mounted on one wheel. This finger rotates a gear (grey) on each turn. This gear should have 400 cleats. One of those cleats is extended. This extension rotates another gear (blue), which lies horizontal.
This horizontal gear is only rotated once per mile, because the big wheel rotates slowly.
There are about 25 holes in the horizontal gear. In it are small stones. When the wheel turns, one stone will fall into a pot.
If you want to count the miles you went on one day, you just have to count how many stones are in that pot. The number of stones equals the miles you went.

Ancient Greece: The Water Clock (Clepsydra) Of Ktesibios

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Water clocks were placed on public places in Ancient Greece. Even more often you could see them in court, to limit the speech time.
Water fills a canister. A float is lifted. A figure is mounted on its top, which points to a cylinder-shaped board. On the board are 24 squares, which stand for hours.
When the canister is full (24 hours have passed), the water flows through the pipe. The out flown water powers a gear, which rotates the board. The further the board rotates, the more days pass.

This simple piece of mechanics, adjusted rightly, could be quite precise.

Ancient Greece: Herons Trumpet Signal

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For the use in temples, Heron proposes following construction in his 'Pneumatic':
A rope is mounted on the door of the temple, which pulls a lever. This lever pushes a hemisphere into a water jar. The water presses air into the hemisphere. This air will now float through a trumpet, which is mounted on the hemisphere. A tone is created by pressure.
If the door is closed, the lever falls back to its first position. The hemisphere lifts and air will float into it.

Ancient Greece: The repeating catapult of Dionysius of Alexandria

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Dionysius of Alexandria invented this wonder of ancient Greece mechanics. The catapults accuracy has not been beaten in Ancient Times. We do not know if it was used on greater occasions.
The only thing one has to do is to turn the wheel back and forth. The wheel moves two chains, which in turn moves a slider.
On the slider lies the arrow. A claw keeps hold of the bowstring. The claw lifts, when a joint is rotated. The arrow flies away.
An arrow magazine is attached on top. The arrows make their way through a rotating tray with cam groove. The tray rotates, when the finger moves back and forth inside the cam groove.