Ctesibius

Ancient Greek alarm clock

The first alarm clock mentioned historically is one used by Plato, possibly to signal the beginning of his dawn lectures. It is said to have emitted an organ-like sound.

The first practical alarm clock was invented by Ctesibius in Alexandria, Ptolemaic Egypt. Ctesibius was the author of On Pneumatics, and is often referred to as “the father of pneumatics,” due to his work on air compression and elasticity.

Even though his inventions are well known, little is known about Ctesibius (floruit 285 – 222 BC) himself, although he is thought to have been originally a barber and the first head of Alexandria’s Museum. He also invented a counterweight-adjusted mirror, the hydraulis (the ancestor to today’s pipe organ), and described force pumps to remove water from wells.

In his efforts to create an improved clepsydra, or water clock, he added a dial with hands and other advancements. So successful were his innovations, that this became the most accurate form of timekeeping until Christiaan Huygens used a pendulum to regulate clocks in the 17th century.

In his efforts to improve the clepsydra, Ctesibius also gave thought to an improved alarm system. In the past, alarm clocks were generally regulated by the trickle or dropping of water into a vessel of a determined volume. Once a certain mass of water in the vessel had been achieved, it acted as a counterweight, forcing an action, such as the tipping over of another container, spilling pebbles onto a bell, or tripping a lever, causing a compression of air to make a horn sound. These methods, while effective, would not work more than a few moments, and would not necessarily get the attention of the individual who first set the alarm, particularly if they were sleeping.

After some thought on the matter, Ctesibius must have somehow struck on what we know as today to be electricity to get the attention of the recumbent alarm setter. The Greeks had long known of the properties of friction on thin rods of amber to produce a static charge. Ctesibius set about adapting this knowledge to wake people up.

Just off the coast of mainland Greece is the island of Lefkada, where for some time experiments had been carried out using Ionian currents, and how to store them. In essence, highly fired amphorae with finely beaten silver lining their interiors to just short of the neck were made. These were then filled with poor quality wine, and then connected to a sulphur ball which was rotated rapidly against animal fur. The resulting friction produced a sufficient static electric charge to shock a person. Ctesibius incorporated one of these Ionic current jars to his improved clepsydra, attaching two leads, one a thin beaten copper strip, one a thin beaten iron strip to the charged Ionic jar, with the other ends to a sort of leather hat on gimbals (Philo of Byzantium, 280 – 220 BC) to be worn by the sleeper. With the leads placed at each temple, the improved clepsydra could be set for a certain time, at which a connection would be made, and an electric shock would waken the sleeper. Later models also incorporated an auditory alarm, such as Ctesibius’ hydraulis.