Posts about history

How Eratosthenes Estimated the Circumference of the Earth Over 2,000 Years Ago

In this video Carl Sagan explains how Greek astronomer Eratosthenes, in 200 BC, was able to deduce and calculate the earth was a sphere about 40,000 km in circumference.

It is wonderful to see how a bit of thought and curiosity have lead mankind to learn so much.

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Dinosaur Bird Wing and Feather in Amber

Rare Dinosaur-Era Bird Wings Found Trapped in Amber

Two tiny wings entombed in amber reveal that plumage (the layering, patterning, coloring, and arrangement of feathers) seen in birds today already existed in at least some of their predecessors nearly a hundred million years ago.

Skin, muscle, claws, and feather shafts are visible, along with the remains of rows of feathers similar in arrangement and microstructure to modern birds.

photo of dinosaur wing in amber with feathers visible

The nearly 100 million year old wing shows a structure that is very similar to modern birds.

The piece in this photo, and others samples, were bought at an amber market in Myitkyina, the capital of Kachin state in northern Myanmar. The region is politically unstable and most of the amber is sold to Chinese consumers for jewelry and decorative carvings.

Read the related posts for more on the wonderful discoveries saved in amber of hundreds of millions of years. We get to read about these amazing discoveries so often it is easy to lose appreciation for how amazing each one is. This photo shows a wind that was used by a dinosaur almost 100 million years ago.

Related: Marine Plankton From 100 Million Years Ago Found in Amber 2008)Learning About Life over 200 Million Years Ago From Samples Trapped In Amber (2012)The evolution of birds from small predatory dinosaursDino-Era Feathers Found Encased in Amber (2008)Amber Pieces Containing Remains from Dinosaurs and Birds Show Feather Evolution (2011)Ancient Whale Uncovered in Egyptian Desert

Ancient Chinese Natural Gas Drilling Using Bamboo

This very interesting article is a great read about the history of Chinese bamboo drilling by Oliver Kuhn.

The first recorded salt well in China was dug in Sichuan Province, around 2,250 years ago. This was the first time water well technology was applied successfully to the exploitation of salt, and marked the beginning of Sichuan’s salt drilling industry. From that point on, wells in Sichuan have penetrated the earth to tap into brine aquifers, essentially ground water with a salinity of over 50g/l. The water is then evaporated using a heat source, leaving the salt behind.

At some point around 2,000 years ago the leap from hand and shovel dug wells to percussively drilled ones was made. By the beginning of the 3rd century AD, wells were being drilled up to 140m deep. The drilling technique used can still be seen in China today, when rural farmers drill water wells. The drill bit is made of iron, the pipe bamboo. The rig is constructed from bamboo; one or more men stands on a wooden plank lever, much like a seesaw, and this lifts up the drill stem a metre or so. The pipe is allowed to drop, and the drill bit crashes down into the rock, pulverizing it. Inch by inch, month by month, the drilling slowly progresses.

A major breakthrough was achieved around 1050 AD, allowing deeper wells, when solid bamboo pipe was replaced by thin, light, flexible bamboo “cable”. This dramatically lowered the weight that needed to be lifted from the surface, a weight that increased with the depth being drilled. By the 1700s Sichuan wells were typically in the range of 300 – 400m deep

One bamboo pipe line would take away the brine, and others the gas. The 2,000 year plus Sichuan salt industry has drilled approximately 130,000 brine and gas wells, and 10% of those were in the immediate Zigong area. Zigong has a cumulative gas production over this period of over 30 billion cubic metres. The area continues to be a major salt producer, and many of the historical wells are still in production.

drawing of Chinese drilling scene

An ancient sketch originally from “The Annals of Salt Law of Sichuan Province”. A “Kang Pen” drum is seen in the centre foreground, with gas pipes directly feeding the salt stoves on the right. At the top, brine from a remote well is being carried in buckets by men, who feed it into a bamboo pipeline that runs down to the stoves. One of the carriers is being paid at top left, and it appears that a blow out is depicted on a new well being drilled.
(from Zhong & Huang)

As recently as the 1950s there was still over 95km of bamboo pipeline in operation in the Zigong area.

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Huge Human Population Boom 40,000 to 50,000 Years Ago

Interesting open access paper on looking at the Y-chromosome to explore our ancestry: A calibrated human Y-chromosomal phylogeny based on resequencing. I can’t understand all the details but the basic idea isn’t that complicated. It is interesting to see these details as are the conclusions that can be drawn: that we had a big explosion of human population o 41,000–52,000 years ago.

This population explosion occurred, between the first expansion of modern humans out of Africa 60,000 to 70,000 years ago and the Neolithic expansions of people in several parts of the world starting 10,000 years ago.

“We think this second, previously unknown population boom, may have occurred as humans adapted to their new environment after the first out-of-Africa expansion,” says Dr Qasim Ayub, lead author from the Wellcome Trust Sanger institute. “We think that when humans moved from the horn of Africa to Asia, Australia and eventually Europe, they remained in small groups by the coasts. It took them tens of thousands of years to adapt to the mountainous, forested surroundings on the inner continents. However, once their genetic makeup was suited to these new environments, the population increased extremely rapidly as the groups travelled inland and took advantage of the abundance of space and food.”

The work highlights how it is now possible to obtain new biological insights from existing DNA sequencing data sets, and the value of sharing data. The majority of the DNA information used for this study was obtained from freely-available online data-sets.

This is the first time researchers have used the information from large-scale DNA sequencing to create an accurate family tree of the Y chromosome, from which the inferences about human population history could be made.

Full press release

Related: Laser Tool Creates “blueprints” of Archeology SitesHHMI on Science 2.0: Information RevolutionScientists crack 40-year-old DNA puzzle

Underwater Pedestrian Bridge

photo of a 'bridge' parting the waters to allow pedestrian to pass

The Dutch water line was a series of water based defenses conceived by Maurice of Nassau in the early 17th century, and completed by his half brother Frederick Henry. Combined with natural bodies of water. The line could be used to protect the economic heartland of the Dutch Republic behind difficult to cross water barriers, when in danger.

The Fort de Roovere was part of this defense. In 2010 the fort was renovated and the moat revived with a small extra bit of engineering: a sunken pedestrian “bridge.” Where once engineers used ingenuity to use water to keep people out, now engineers used wood to let people experience the moat while still reaching the fort.

via: Sunken Pedestrian Bridge in the Netherlands Parts Moat Waters Like Moses!

Related: Monitor-Merrimac Memorial Bridge-TunnelMonkey BridgeQuantum Teleportation

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