Technology, World-Changing Inventions

Water Treatment Technology Through History

Water Treatment Technology Through History


Civilization has changed in uncountable ways over the course of human history, but one factor remains the same: the need for clean drinking water. Every significant ancient civilization was established near a water source, but the quality of the water from these sources was often suspect. Evidence shows that humankind has been working to clean up their water and water supplies since as early as 4000 BCE.

Cloudiness and particulate contamination were among the factors that drove humanity’s first water treatment efforts; unpleasant taste and foul odors were likely driving forces, as well. Written records show ancient peoples treating their water by filtering it through charcoal, boiling it, straining it, and through other basic means. Egyptians as far back as 1500 BCE used alum to remove suspended particles from drinking water.

By the 1700s CE, filtration of drinking water was a common practice, though the efficacy of this filtration is unknown. More effective slow sand filtration came into regular use throughout Europe during the early 1800s.

As the 19th century progressed, scientists found a link between drinking water contamination and outbreaks of disease. Drs. John Snow and Louis Pasteur made significant scientific finds in regards to the negative effects microbes in drinking water had on public health. Particulates in water were now seen to be not just aesthetic problems, but health risks as well.

Slow sand filtration continued to be the dominant form of water treatment into the early 1900s. in 1908, chlorine was first used as a disinfectant for drinking water in Jersey City, New Jersey. Elsewhere, other disinfectants like ozone were introduced.

The U.S. Public Health Service set federal regulations for drinking water quality starting in 1914, with expanded and revised standards being initiated in 1925, 1946, and 1962. The Safe Drinking Water Act was passed in 1974, and was quickly adopted by all fifty states.

Water treatment technology continues to evolve and improve, even as new contaminants and health hazards in our water present themselves in increasing numbers. Modern water treatment is a multi-step process that involves a combination of multiple technologies. These include, but are not limited to, filtration systems, coagulant (which form larger, easier-to-remove particles call “floc” from smaller particulates) and disinfectant chemicals, and industrial water softeners.

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Planned future articles on Sandy Historical will expand on some of the concepts mentioned here. Please visit this page again soon for links to further reading.

Technology, The Science of Film, Music & Art

The Printing Press After Gutenberg, Part I

We all know Big John Gutenberg is responsible for the invention of the printing press, way back in Ye Olde Fifteenth Century CE. But there have been a ton of new advances in printing press technology since then. What else does the world of the printing press have in story for the historically inclined? Read on to find out, and look for Part II of this series in the near future. (Date TBA.)

A modern offset printing press running at full bore.

A modern offset printing press running at full bore.

Advanced Lithography

Offset printing is a common printing method that transfers an inked image or type from a hand-carved metal plate to a rubber blanket to the printing medium. A variation on the lithographic printing process, this technique uses the natural repulsion of oil and water to keep the non-printed areas of the image or text frame ink-free.

Lithography itself was originally intended as an inexpensive way to reproduce artwork. However, it proved difficult to reproduce images/text quickly and clearly with standard lithography methods.

The offset printing press was invented in England in 1875 by Robert Barclay. Barclay combined the basic technique used in lithography with mid-19th century CE transfer printing processes and the rotary printing press. Invented by American inventory Richard March Hoe in 1843, the rotary printing press used a metal cylinder to transfer inked images and/or text instead of the flat stones used in lithography.

Barclay added a cover around the roller; manufactured from specially treated cardboard, the roller assisted in transferring the ink the printed surface. The cardboard was later replaced with rubber, which is still used in offset printing today. The rubber-coated roller was later discovered (accidentally, by New Jersey photographer Ira Washington Rubel) to be ideal for reprinting photos on photo paper, as well.

Occam’s Razor?

Technological advances make the modern offset printing press a far faster and more efficient machine than Barclay’s original device. Computer programs provide perfect recreation of the original image or text; automation allows the system to operate at much, much higher speeds; and, of course, electrical power makes it all possible.

However, to actually print the image or text, today’s offset presses still transfer ink to rubber rollers which produce the image/text on the print surface. Barclay’s general principle remains intact. One hundred forty years later, the original technology is still the most effective. Truly a rarity in the modern world.

Photo credit: Kelly Sue / Foter / CC BY-SA

Historical Science & Technology

Astronomy in the Hellenistic Period

Running for just under three centuries, from 323 BCE to 31 BCE, the Hellenistic period of ancient Greek and Mediterranean history saw Greek cultural influence at its peak across the known world (which, at the time, was Europe, Africa, and Asia). The Hellenistic period saw great strides in numerous areas, including the arts, literature, philosophy, and science. In the scientific field, astronomers made a number of important discoveries.

Planetary Models

The accepted planetary model at the time was the Eudoxan system. This model was accurate at the basest levels, but was riddled with significant flaws. Among them: it did not predict planetary motion exactly; it did not explain why planets appear to change speeds; it did not explain changes in the brightness of planets as seen from Earth; and, in its use of concentric spheres to represent planetary orbits (called “deferents”), maintained that all other planets always stay the same distance from ours. (Keep in mind this was a time when Earth was still thought to be the center of the universe–see below.)

To address these inconsistencies, Apollonius of Perga introduced two new mechanisms to the existing model. First, eccentric deferents acknowledged that some planets may move on slightly off-center orbits, thus accounting for variable distances and the accompanying variable brightness. Second, Apollonius’ deferent and epicycle model compounds this by adding a smaller circular orbit in which a planet may travel while traversing its main orbit around the earth. Appolonius’ model at least partially explained the retrograde motions planets appear to go through, in which they seemingly reverse their motion through the celestial Zodiac.

Diagram of a planetary orbit in the deferent and epicycle model.

Diagram of a planetary orbit in the deferent and epicycle model.

Observational Astronomy

Hipparchus, a circa 2nd century BCE astronomer, geographer, and mathematician, insisted that Greek astronomers meet or exceed the accuracy of Babylonian astronomers when predicting planetary motion. Using existing Babylonian references, as well as observations of equinoxes and lunar cycles, he created thorough geometrical models of the motion of Moon and the (apparent) motion of the Sun. However, Hipparchus was unable to create accurate models for the remaining planets.

Later, Hipparchus compiled the first star catalogue. He recorded the positions and brightness of observable stars, so that future astronomers could tell whether these stars moved, changed in brightness, or died, or if new stars were born. The potential movement of stars was attributed to the motion of the celestial sphere, to which (it was then thought) all stars are affixed.


Though his theory wasn’t proven correct until centuries later, Aristarchus of Samos proposed a new cosmological arrangement that put the Sun, not Earth, at the center of the known universe. This idea was not well-received, and most references to Aristarchus’ work have been lost to history. The astronomer and philosopher Seleucus of Seleucia is the only known contemporaneous supporter of Aristarchus’ heliocentric model, but we all know better now, don’t we?!

Cosmic Scales

Not one to let worldwide critical contempt slow him down, Aristarchus also wrote one of the definitive early works on cosmic scale—also the only significant piece of his writing still known today. In On the Sizes and Distances of the Sun and Moon, he calculated the sizes of the Sun and Moon and their distances from the Earth, measured in Earth radii. (Talk about an on-the-nose book title, amirite?)

Photo credit: Internet Archive Book Images / Foter / No known copyright restrictions


Hayabusa: Japan’s Asteroid Sampling Spacecraft

Launched in May 2003, the Hayabusa was developed and launched by the Japan Aerospace Exploration Agency (JAXA—essentially Japan’s NASA). The unmanned spacecraft rendezvoused with the small, near-Earth asteroid 25143 Itokawa in November 2005, extensively studied the asteroid, collected samples, and successfully returned to Earth. It was decommissioned upon its return in June 2010.

Mission to Mars An Asteroid

Upon reaching space after its launch in the early morning hours of 9 May 2003 from Japan’s Uchinoura Space Center, Hayabusa (“peregrine falcon”) flew through the cosmos on the power of its four xenon ion engines for nearly two years straight. As it approached Itokawa in September 2005, Hayabusa settled into a heliocentric orbit around the asteroid and surveyed its surface from a distance of roughly 12.4 miles (20 kilometers).

Following its initial visual reconnaissance, Hayabusa slowly but surely moved closer to the asteroid’s surface. The spacecraft executed a number of soft landings, during which it collected surface samples from a pre-selected “safe site.” Real-time command from JAXA was impossible due to the long communications delay caused by sheer distance, so Hayabusa operated via autonomous optical navigation.


Each time its collection device contacted Itokawa, Hayabusa automatically fired miniscule projectiles at the asteroid’s surface and collected the resulting spray; the collected particles were stored onboard for further study upon the craft’s return to Earth.

Though Hayabusa was not intended to actually land on the asteroid, it did so briefly, coming to rest on Itokawa’s surface for roughly 30 minutes.

After “following” the asteroid for several months and collecting various samples—and following minor problems with its thrusters and altitude controls—the spacecraft began its return to Earth. Hayabusa’s reentry capsule detached from the main body of the craft, and “coasted” back to Earth on a ballistic trajectory. After experiencing peak deceleration of approximately 25G, the capsule landed safely via parachute near Woomera, Australia.

Multiple Firsties

While Hayabusa was not the first spacecraft to visit an asteroid, it was the first collect material samples and bring them back to Earth. It was the first spacecraft designed from the start to make physical contact with an asteroid. Following its incidental landing (see above), Hayabusa was the first spacecraft to land on an asteroid and take off again; NASA’s NEAR Shoemaker landed on the asteroid it studied on its mission, but did not return to Earth.

Photo credit: geckzilla / Foter / CC BY

Historical Science & Technology

A Brief History of the N-Body Problem

Motivated by the desire to understand the motions of the Sun, Moon, planets, and visible stars, the n-body problem is a series of physics equations used to predict the individual motions of celestial bodies and their gravitational effects on each other’s motion. Like many an old school physics jam, this nut was first cracked by Sir Isaac “Don’t Call Me Fig” Newton.

I Like Ike

Working with astronomer John Flamsteed, Newton gathered orbital positions of several planets’ orbits and produced a functional equation based on analytical geometry that predicted the planets’ motion and various orbital properties, including position, diameter, period, and velocity. However, after studying the predictions of his equation for several years, Newton and his squad discovered that those predictions were not terribly accurate in most cases.

Newton deduced that the interactive gravitational forces of the planets were affecting their orbits. Further study led to the realization that the factors on which he based his equation—initial and additional orbital positions, orbital velocity—were insufficient to determine a planet’s actual orbit; interactive gravitational forces had to be factored in, as well. While these forces conform to Newton’s Laws of Motion and Law of Universal Gravitation, the n-body (multiple body) interactions made it extremely difficult to find an exact solution.

"Physics is a piece of cake" - Newton, probably

“Physics is a piece of cake” – Newton, probably

In his Pricipia, Newton addressed the n-body problem thusly:

“And hence it is that the attractive force is found on both bodies. The Sun attracts Jupiter and the other planets, Jupiter attracts is satellites and similarly the satellites act on one another. And although the actions of each of a pair of planets on the other can be distinguished from each other and can be considered as two actions by which each attracts the other, yet inasmuch as they are between the same, two bodies they are not two but a simple operation between two termini. Two bodies can be drawn to each other by the contraction of rope between them. The cause of the action is twofold, namely the disposition of each of the two bodies; the action is likewise twofold, insofar as it is upon two bodies; but insofar as it is between two bodies it is single and one…”

Further, Newton deduced via his 3rd Law of Universal Gravitation that “according to this Law, all bodies must attract each other.”

King Oscar’s N-Body Ransom

After Newton checked out, lots of attempted to devise equations that would produce a general solution to the n-body problem. By the late 19th century CE, solving the n-body problem was of such importance that King Oscar II of Sweden offered a substantial prize for anyone who could solve it. The announcement of the prize stated, in part:

“Given a system of arbitrarily many mass points that attract each according to Newton’s law, under the assumption that no two points ever collide, try to find a representation of the coordinates of each point as a series in a variable that is some known function of time and for all those whose values the series converges uniformly.”

As a backup plan—in case no one could provide a solution—any other significant contribution to classical mechanics was also considered worthy of the prize. Ultimately, the prize was awarded to French mathematician and theoretical physicist Henri Poincaré, who did not actual solve the -body problem. Poincaré’s first attempted solution contained a number of significant errors, but the final, “official” version included numerous important ideas that later contributed to the creation of chaos theory.

The solution to King Oscar’s problem, as originally stated, was discovered by Finnish mathematician Karl F. Sundman.

Photo credit: amcdawes / Foter / CC BY-SA

Historical Science & Technology

The Rise & Fall of The Library of Alexandria

The Royal Library of Alexandria is perhaps the most famous, and certainly one of the largest and most significant, libraries of the ancient world. Dedicated to the nine Muses, and intended as a display of the wealth of Egypt under the Ptolemaic Dynasty, the Library of Alexandria stood as a symbol of cultural progress for hundreds of years until it was destroyed by fire, along with an incalculable amount of collected knowledge, in the early centuries CE.

A Riddle, Wrapped In A Mystery, Inside An Enigma, Slathered in BBQ Sauce

The Library of Alexandria (just “the Library” from here on out) is probably most famous for having been burned down by an invading army, an act that has come to symbolize the intentional destruction of culture and knowledge of any kind. However, beyond its fame as a repository for vast amounts of written knowledge (the exact number of scrolls housed in the Library is unknown, but one of its leading patrons, King Ptolemy II Philadelphus, set a goal of 500,000 during his reign) and the notoriety of its destruction, little is known about the Library itself.

Modern knowledge of the Library is a spicy stew of true history, myth, and legend. The year(s) of its construction are unknown, as is the exact date on which it was destroyed. The earliest known reference to the Library is in the Letter of Aristeas, written between 180 and 145 BCE. The Letter states that construction began under the reign of Ptolemy I Soter in the mid-4th century BCE; other sources give the date as a century or more later.

The Library’s layout and exact dimensions are unknown, but we do know it was built in the style of Aristotle’s Lyceum and located in the city’s Royal Quarter, adjacent to the Musaeum of Alexandria. Officially tasked with collecting all of the world’s knowledge, and well-funded by royal decree, most Library staff kept busy translating works onto papyrus scrolls. Legend has it that any book found on any ship coming into the harbor was immediately taken to the Library for translation/copying.

The Library also served as a global center for research and learning. Many of the world’s greatest scholars were hosted there and funded for travel, lodgings, and stipends (for their entire families) by the Library’s Ptolemaic patrons.

The Library, The Library, The Library of Alexandria is On Fire

The Cliffs Notes version of Egyptian history will tell of the burning of the Library, but it’s possible—likely, even—that the Library was actually destroyed by a series of fires and/or other destructive acts. Centuries of research have identified four possible causes of the Library’s destruction.

Scenario #1: In 48 BCE, Julius Caesar’s troops lay siege to Alexandria, and in taking the city, may have accidentally set fire to the Library. Several ancient texts state that the Library was only damaged in the fire and not completely destroyed. Others state that, based on contemporaneous maps and other resources, the Library was burned down to its foundation during Caesar’s siege.

Scenario #2: In the 3rd century CE, Roman Emperor Aurelian’s troops fought in Alexandria to suppress a revolt led by Queen Zenobia of Palmyra. During the fighting, many areas of the city were severely damaged or destroyed by a number of fires, several areas adjacent to the Library among them. It is possible the Library was destroyed, as well. Writings of the era offer conflicting evidence.

Detail of a 5th century CE scroll depicting Theophilus: Destroyer of Libraries.

Detail of a 5th century CE scroll depicting Theophilus: Destroyer of Libraries.

Scenario #3: Roman Emperor Theodosius outlawed paganism in 391 CE; an accompanying decree from Pope Theophilus of Alexandria closed the city’s temples. “Closed” being code, apparently, for destroy, as most of Alexandria’s “heathen” temples were demolished, including the Serapeum, which housed a substantial portion of the Library’s collection at the time. Contemporaneous writings make no mention of the Library’s destruction at this time, though several compare the burning of the scrolls to the destruction of the Library itself by Julius Caesar. (See Scenario #1.) Some modern researchers believe the Library was destroyed at this time, but not as part of the decree; rather, the Library was burned down during the ensuing religious riots.

Scenario #4: In 642 CE, general ‘Amr ibn al ‘Aas led the Muslim conquest of Egypt, marching his army through Alexandria in the process. Much contemporaneous writing supports this version of events, though it comes almost exclusively from Muslim sources; the story was reinforced by various sources well into Medieval times. However, most modern scholars agree that this scenario is highly unlikely, and that the ongoing written and oral support it received was naught but grandstanding.

Photo credit: Foter / Public Domain Mark 1.0