Technology, World-Changing Inventions

A Brief History of Optical Telescopes

The first example of a working telescope was invented in 1608 by Hans Lippershey of Middleburg, The Netherlands. Through others, his arrangement of mirrors and lenses would go through countless evolutions over time, and come to be one of the most useful scientific inventions in history.

Optical Forerunners

The optical properties of convex and concave transparent objects have been known for thousands of years. The first glass lenses were not created until the late 1200s, when techniques for making glass had advanced enough to produce relatively inexpensive, relatively clear glass. Advancements in grinding and polishing glass also contributed significantly.

Before long, small, wearable sets of lenses were used to correct visions—the first eyeglasses. Methods of correcting both farsightedness and nearsightedness were created. These lenses, along with greatly refined glass mirrors, further set the stage for the telescope.

The First Telescopes

Though two others made their own claims to the device’s invention at the same time, Lippershey, spectacle maker, was the first disseminate designs for the telescope, and the first to apply for a patent.

Lippershey’s original telescope was composed of a single convex lens and a single concave lens in a wooden tube, providing 3X magnification. Soon, the “Dutch perspective glass” was being built by lens and spectacle makers throughout the Netherlands, spreading quickly across Europe and evolving rapidly with new technological advancements.

Sir Isaac Newton is credited with creating the first practical reflector in 1668, using a design that included a small, flat, diagonal mirror that reflected light into an eyepiece mounted on the side of the telescope.


The achromatic telescope was invented by Chester Moore Hall in 1733. Using improved lenses, these telescopes reduced color aberrations and could be far shorter and  more functional than previous designs. Hall did not widely publicize his discovery, and the achromatic telescope did not see wide use until John Dollond began producing them in large quantities in the late 1750s.

The Telescope Gets Larger & More Powerful

In 1789, Sir William Herschel built a giant telescope, forty feet long and with a mirror four feet in diameter. This reflector design, with its huge mirror, was capable of gathering hundreds or thousands of times more light than a refractor telescope.

In 1856, a new process of depositing layers of silver on glass telescope mirrors was discovered by Leon Foucault and Karl August von Steinhall. The silver layer provided much greater reflectivity and longevity that the finish on the speculum mirrors used until that time. It also possible to remove and renew the coating without unwanted modification of the glass substrate.

Using improvements to this technique and other technological advancements, the first large, modern research reflectors were built in the early 20th century. These telescopes were designed specifically for high quality photographic imaging and installed in remote high altitude locations. Examples include the Hale telescope at the Mount Wilson Observatory (built in 1908) and the Mount Wilson Hooker telescope (1917), which measured 100 inches in length.

In 1932, a replacement for the telescopes’ silver lens coating was developed. Using thermal vacuum evaporation, a much longer lasting aluminum coating could be applied. An aluminized lens was used in what was then the world’s largest telescope, the 200 inch Hale reflector at Mount Palomar, in 1948.

Photo credit: El Bibliomata / Foter / Creative Commons Attribution 2.0 Generic (CC BY 2.0)


Paper Making Machines: A Brief History & How They Work

The first machine for making continuous sheets of paper was invented by Louis-Nicholas Robert in France in 1798. Robert’s machine became known as the Fourdrinier Machine, named after the Fourdrinier Brothers who financed its invention. Most modern paper making machines are derived from the original Fourdrinier model.

Prior to the invention of paper machines, individual sheets of paper were made by either pouring wood pulp slurry into a sheet mold (a type of fabric sieve) or by dipping the sheet mold into a vat of slurry. After being pressed to remove excess water, each paper sheet would be hung over a rope or wooden rod to air dry.

Fourdrinier Machines—and most, if not all, paper making machines based on its design—use a specially woven fabric mesh conveyor belt at the wet end (where the wet wood pulp enters the machine) to create a long, continuous paper web. Originally, this conveyor was made of bronze wire; modern machines use a special plastic fabric.

After the invention of his first paper machine, for which Roberts was granted the French patent in 1799 (the British patent went to John Gamble, an indirectly related player in its invention, in 1801), Roberts and Bryan Donkin created a series of significantly improved versions throughout the first decade of the 19th century.

The first paper machine in the United States was a cylinder mold machine, installed at Gilpin’s Mill in Delaware in 1817. The Fourdrinier Machine was introduced to the US a decade later.

Modern paper machines have four distinct sections. First is the forming section (a.k.a. “the wet end,” as mentioned above), where the wood pulp slurry is turned into a web of paper fiber on the machine’s fabric conveyor belt. Second is the press, where the continuous feed of paper fiber is fed through large rollers which squeeze the water out of the fiber using high pressure. Third is the dryer, where the paper fiber travels a serpentine route through a series of heated cylinders which further remove water content. Last is the calender section, where the now-dried paper is smoothed by heavy steel rollers.

From there, a separate machine cuts the long, continuous paper sheet into individual sheets of the required size.

Because the process of making paper has changed very little in the past 200 years, and because papermaking machines are generally built very robustly, they often remain in service for many decades with only very minor alterations and upgrades.

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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.