Recently i Applied Engineering A YouTube channel has shown a working recreation of a pump design that some believe was used to pump water up to the ancient Alhambra palace and its citadel, located in what is now Spain. This so-called pulser pump design is notable for having no moving parts, but the water pump is one of the many interesting engineering achievements that made the Alhambra a truly unique place before the ravages of time caught up with it.
Although the engineering work is said to have been active in the 18th century, this pumping system and many other elements that existed at the height of its existence had already disappeared in the 19th century for many reasons. During this century a Spanish engineering professor, Cáceres, tried to reconstruct the machine as best he could based on the remaining descriptions, but unfortunately we will probably never know for sure what was there.
Similarly, the fountain based on the supposed period in the Court of Lions and other elements are now lost to time, but we have many ideas of how this all worked in the pre-industrial era.
The Alhambra
A UNESCO World Heritage Site since 1984, the Alhambra was first built in 1238 CE by Muhammad I, the first Nasrid ruler. The Nasrid dynasty would last from 1238 to 1491 CE when the Islamic state of al-Andalus fell during the Christian Reconquista.
Even after the end of the Nasrid dynasty, the Alhambra would see further construction by Charles V in the 16th century. This makes the Alhambra a unique combination of Islamic and Renaissance architecture and engineering. Sadly by the 18th century the building had been abandoned for centuries, invaded by squatters, and partially destroyed by Napoleon’s troops in 1812.
It was after these troubled times that the appreciation of such traditions began to flourish, as European and American tourists alike frequented the area. One of them – the American writer Washington Irving – was inspired by his visit in 1828 and eventually wrote. Legends of the Alhambrawhich contains many legends, stories, drawings, and articles about the site. This book in particular has been instrumental in making a global audience aware of this site and its legacy.
This rediscovery led to the site being recognized first as a Spanish Cultural Heritage monument in 1870 and then by UNESCO more than a century later.
Features of Water
Many castles of the time relied heavily on aquifers that collected rainwater, as well as access to local rivers in some way, often requiring human or animal labor to transport the rainwater. This was also how the Alhambra began as its first fortress, called the Alcazaba, which means ‘castle’ in Spanish, from the Arabic language. al-qaṣabah. The water from this well not only provides drinking water, but also the bathhouse (hammam) and water features such as a pool or well for houses within the city area. These houses also had toilets that were flushed using this well water.
As the Alhambra expanded, as there were more palaces and buildings associated with it, its water needs increased accordingly. Instead of a dozen small decorative water features and communal baths, there were now sparkling pools, fountains and a larger population. This made it necessary to find more efficient ways to get more water from the hill on which the Alhambra was built.
In addition to the pump mentioned above, there was also a water channel (i Acequia Real) that carried water from the Darro River. At a distance of 6.1 km from the fort the river is at a height high enough to provide water using only gravity. This aqueduct also supplies water through additional branches to the garden and residences outside the walls of the Alhambra.
More details can be found in this 2019 summary of hydraulic techniques used in al-Andalus castles by Luis José García-Pulido and Sara Peñalver Martín.
As noted in that revised article, the reason that the Alhambra is more advanced than other castles in the region of al-Andalus is that it was the seat of the Nasrid dynasty, ergo it was natural that it would not only have all the palaces and comforts, but also the most advanced water supply technology.
Unfortunately the unique pumping device used to supply the Alcazaba with water from the aqueduct was replaced in the 18th century with a rudimentary siphon system and the original device was removed. Until then the previous device had continued to function, despite the fact that the Alhambra’s new owners did not understand its working principles. This left 19th century researchers like Cáceres to rely entirely on notes made during the previous century.
That said, there are also suggestions that the Alcazaba of Antequera castle used a similar device to pump water uphill, containing ceramic pipes and other features described by Sancho de Toledo in 1545. Unfortunately these accounts were all written by people who had no knowledge of the engineering of the early Nasrid engineers – or any knowledge of engineering they had no knowledge of the engineering of working pumps.
This means that unfortunately we will never know exactly what this device looked like or how it worked, but we can still look at other methods that we are used to today. The idea of a hydraulic ram or pulser pump may seem very close compared to what little we know.
Self Powered Pumps
Unlike a water pump that uses e.g. an impeller to provide kinetic energy and thus move the liquid, a self-propelled pump uses physical properties such as the water hammer effect or the fact that gas in a liquid will rise to create a pumping effect. A hydraulic ram, for example, uses the effect of a water hammer and relies only on the kinetic energy of incoming water.
The basic sequence of operation of a hydraulic ram involves the force of water pushing a waste valve normally open, where the effect of the water hammer from the sudden interruption of current forces the delivery valve to open and push water into the delivery pipe.
This process will reverse again after a while, sending a pressure wave upstream and eventually leading to the reopening of the waste valve. The flow of the river will then resume, starting the whole process over.
In terms of technical complexity, this is a very specific design, with very complex components such as valves and a pressure vessel that prevents the system against pressure shocks. However this is a design that is technologically feasible to implement and work.
Another, similar type of pump is the gas lift pump. A very small variant of this is often used in devices such as coffee makers, where a pulser pump is actually used for the same general purpose. Rather than applying heat to a reservoir to create a gas (ie, steam), a pulser pump uses the same air pressure effect that is used with water-powered trompe air compressors.
As the water falls down the pipe it pulls air bubbles along with it, eventually reaching the bottom where said air is trapped in the hole while the water flows to the bottom.
A thin pipe through which water is pumped is placed in this air chamber in such a way that it will admit water and air as the latter’s level changes over time. In this way the water pockets are trapped between the air pockets, which leads to the discharge of water at the end of the pipe.
Whether the original device in Alhambra or Antequera is exactly the same as any pump design will probably remain a mystery, but it was also beyond the technological means of the time, where the pulser pump is undoubtedly more straightforward due to the lack of need for any valves and pressure vessels.
Time or Source You’re Watching
Although the Applied Engineering The video focuses on this pump design, whose author – Grady – was inspired by Primal Space the video is basically just historical content, not citing any relevant sources and spreading myths and misinformation as fact. The worst case is probably the legend that this fountain found in the Court of Lions worked in time, and the only evidence of it is the clock that has twelve lion images and is doubled for twelve hours a day.
Considering the archaeological evidence available so far, as well as the findings during the recent restoration, it seems clear that the marble block with its many holes where the water enters the basin was intended to distribute the flow. Next to the container we can see a parallel poem of twelve verses by the vizier and the poet Ibn Zamrak.
In verses 3 to 7 it specifically refers to “[..] which flows into that which still exists, we do not know which of them flows.” This strongly suggests that this theme was similar to the many reflecting pools that were popular in the Alhambra and elsewhere.” Thus, the idea of being a time-controlled machine may appear to be a purely Western explanation, with no hitherto unknown evidence emerging.
Lost History
Perhaps the most cruel aspect of history is that, like time itself, it has no interest in us living in the present. Throughout the ages as empires rise and fall to dust, wonderful inventions are made and quickly forgotten, leaving only echoes of deeds and miracles.
If we are lucky some of them are recorded as solidly as the Sumerian clay tablets buried under the desert sands, but otherwise what was there will never be again. This infinity is the eternal curse of the past, and the reason why it is always so important to make multiple copies of your important data.
Due to the passage of time, most of the history is just ruins, pieces of pots and bones buried in mud and sand. Some will try to fix things with human imagination which leads to false love, but this naturally has little connection with the past. That today the Alhambra has been largely restored is a testament to how much more respect we now look to the past, but the parts that were erased after the demise of the Nasrid dynasty may sadly be lost forever.
Featured image: The Court of the Myrtles light pool, looking north towards Comares Tower. (Credit: Tuxyso, Wikimedia)
