Jul 26, 1775: U.S. postal system established

July 26, 2011 · Posted in Uncategorized · Comment 

U.S. postal system established. (2011). The History Channel website. Retrieved 5:14, July 26, 2011, from http://www.history.com/this-day-in-history/us-postal-system-established.
firstpostagestamp
On this day in 1775, the U.S. postal system is established by the Second Continental Congress, with Benjamin Franklin as its first postmaster general. Franklin (1706-1790) put in place the foundation for many aspects of today’s mail system. During early colonial times in the 1600s, few American colonists needed to send mail to each other; it was more likely that their correspondence was with letter writers in Britain. Mail deliveries from across the Atlantic were sporadic and could take many months to arrive. There were no post offices in the colonies, so mail was typically left at inns and taverns. In 1753, Benjamin Franklin, who had been postmaster of Philadelphia, became one of two joint postmasters general for the colonies. He made numerous improvements to the mail system, including setting up new, more efficient colonial routes and cutting delivery time in half between Philadelphia and New York by having the weekly mail wagon travel both day and night via relay teams. Franklin also debuted the first rate chart, which standardized delivery costs based on distance and weight. In 1774, the British fired Franklin from his postmaster job because of his revolutionary activities. However, the following year, he was appointed postmaster general of the United Colonies by the Continental Congress. Franklin held the job until late in 1776, when he was sent to France as a diplomat. He left a vastly improved mail system, with routes from Florida to Maine and regular service between the colonies and Britain. President George Washington appointed Samuel Osgood, a former Massachusetts congressman, as the first postmaster general of the American nation under the new U.S. constitution in 1789. At the time, there were approximately 75 post offices in the country.

Today, the United States has over 40,000 post offices and the postal service delivers 212 billion pieces of mail each year to over 144 million homes and businesses in the United States, Puerto Rico, Guam, the American Virgin Islands and American Samoa. The postal service is the nation’s largest civilian employer, with over 700,000 career workers, who handle more than 44 percent of the world’s cards and letters. The postal service is a not-for-profit, self-supporting agency that covers its expenses through postage (stamp use in the United States started in 1847) and related products. The postal service gets the mail delivered, rain or shine, using everything from planes to mules. However, it’s not cheap: The U.S. Postal Service says that when fuel costs go up by just one penny, its own costs rise by $8 million.

Pythagoras for Kids

July 21, 2011 · Posted in Math · Comment 

 

Pythagoras

http://www.historyforkids.org/learn/greeks/science/math/pythagoras.htm

Pythagoras lived in the 500s BC, and was one of the first Greek mathematical thinkers. He spent most of his life in the Greek colonies in Sicily and southern Italy. He had a group of followers (like the later disciples of Jesus) who followed him around and taught other people what he had taught them. The Pythagoreans were known for their pure lives (they didn’t eatbeans, for example, because they thought beans were not pure enough). They wore their hair long, and wore only simple clothing, and went barefoot. Both men and women were Pythagoreans.

Pythagoreans were interested in philosophy, but especially in music and mathematics, two ways of making order out of chaos. Music is noise that makes sense, and mathematics is rules for how the world works.

Pythagoras himself is best known for proving that the Pythagorean Theorem was true. The Sumerians, two thousand years earlier, already knew that it was generally true, and they used it in their measurements, but Pythagoras is said to have proved that it would always be true. We don’t really know whether it was Pythagoras that proved it, because there’s no evidence for it until the time ofEuclid, but that’s the tradition. Some people think that the proof must have been written around the time of Euclid, instead.

Here is the proof:

The Pythagorean Theorem says that in a right triangle, the sum of the squares of the two right-angle sides will always be the same as the square of the hypotenuse (the long side). A2 + B2 = C2. Try it yourself: if Side A is 4 inches long, and Side B is 3 inches long, then 4×4=16, and 3×3=9, and 9+16=25, and so Side C will be 5 inches long. Try it with other size triangles and see if this is still true (you can use a calculator, or your computer, to figure out the square roots).

But how can you know that this is always true, every single time, no matter what size the triangle is?

Take a straight line and divide it into two pieces, and call one piece a and the other piece b, like this:

Now make a square with this line on each side, like this:

and draw in the lines where A meets B on each side to make four smaller shapes. So now you have one square with area AxA (the big yellow one) and one square with area BxB (the little green one) and two rectangles with area AxB (the light blue ones). So the area of the whole square is (A+B) x (A+B) or the area is (AxA) + 2(AxB) + (BxB).

Or you might say that
(A+B)2 = A2 + 2AB + B2

Now draw diagonal lines across the blue rectangles, making four smaller blue triangles. Call those lines C. Do you see that you have made four blue right triangles, whose sides are A, B, and C?

Now imagine that you take these triangles and rearrange them (or if you print it out you can cut them up with scissors and really rearrange them) around the edges of the square like this:

The little triangles take up part of the square. The area of all four triangles together is the same as the two blue rectangles you made them from, so that is 2AB.

The area of the pink square in the middle is CxC or C2.

And the area of the whole big square is, as we have already seen,
A2 + 2AB + B2
So A2 + 2AB + B2 = 2AB + C2
We can subtract 2AB from both sides, so
that gives (ta da!)

A2 + B2 = C2

Here’s an animated short video showing another way to prove the Pythagorean Theorem.

Tsunami hits Alexandria, Egypt Jul 21, 365

July 21, 2011 · Posted in Uncategorized · Comment 
Tsunami hits Alexandria, Egypt. (2011). The History Channel website. Retrieved 3:47, July 21, 2011, from http://www.history.com/this-day-in-history/tsunami-hits-alexandria-egypt.
Alexandria Egypt
On this day in the year 365, a powerful earthquake off the coast of Greece causes a tsunami that devastates the city of Alexandria, Egypt. Although there were no measuring tools at the time, scientists now estimate that the quake was actually two tremors in succession, the largest of which is thought to have had a magnitude of 8.0.

The quake was centered near the plate boundary called the Hellenic Arc and quickly sent a wall of water across the Mediterranean Sea toward the Egyptian coast. Ships in the harbor at Alexandria were overturned as the water near the coast receded suddenly. Reports indicate that many people rushed out to loot the hapless ships. The tsunami wave then rushed in and carried the ships over the sea walls, landing many on top of buildings. In Alexandria, approximately 5,000 people lost their lives and 50,000 homes were destoyed.

The surrounding villages and towns suffered even greater destruction. Many were virtually wiped off the map. Outside the city, 45,000 people were killed. In addition, the inundation of saltwater rendered farmland useless for years to come. Evidence indicates that the area’s shoreline was permanently changed by the disaster. Slowly, but steadily, the buildings of Alexandria’s Royal Quarter were overtaken by the sea following the tsunami. It was not until 1995 that archaeologists discovered the ruins of the old city off the coast of present-day Alexandria.

Today, the anniversary of the tsunami is celebrated annually with the residents saying prayers and marking the evening by illuminating the city.

The First Battle of Bull Run

July 21, 2011 · Posted in Uncategorized · Comment 
Jul 21, 1861:
Battle of Bull Run--July 21st 1861-500

The First Battle of Bull Run. (2011). The History Channel website. Retrieved 3:20, July 21, 2011, from http://www.history.com/this-day-in-history/the-first-battle-of-bull-run.

In the first major land battle of the Civil War, a large Union force under General Irvin McDowell is routed by a Confederate army under General Pierre G.T. Beauregard.

Three months after the Civil War erupted at Fort Sumter, Union military command still believed that the Confederacy could be crushed quickly and with little loss of life. In July, this overconfidence led to a premature offensive into northern Virginia by General McDowell. Searching out the Confederate forces, McDowell led 34,000 troops–mostly inexperienced and poorly trained militiamen–toward the railroad junction of Manassas, located just 30 miles from Washington, D.C. Alerted to the Union advance, General Beauregard massed some 20,000 troops there and was soon joined by General Joseph Johnston, who brought some 9,000 more troops by railroad.

On the morning of July 21, hearing of the proximity of the two opposing forces, hundreds of civilians–men, women, and children–turned out to watch the first major battle of the Civil War. The fighting commenced with three Union divisions crossing the Bull Run stream, and the Confederate flank was driven back to Henry House Hill. However, at this strategic location, Beauregard had fashioned a strong defensive line anchored by a brigade of Virginia infantry under General Thomas J. Jackson. Firing from a concealed slope, Jackson’s men repulsed a series of Federal charges, winning Jackson his famous nickname “Stonewall.”

Meanwhile, Confederate cavalry under J.E.B. Stuart captured the Union artillery, and Beauregard ordered a counterattack on the exposed Union right flank. The rebels came charging down the hill, yelling furiously, and McDowell’s line was broken, forcing his troops in a hasty retreat across Bull Run. The retreat soon became an unorganized flight, and supplies littered the road back to Washington. Union forces endured a loss of 3,000 men killed, wounded, or missing in action while the Confederates suffered 2,000 casualties. The scale of this bloodshed horrified not only the frightened spectators at Bull Run but also the U.S. government in Washington, which was faced with an uncertain military strategy in quelling the “Southern insurrection.”

Atlantis comes in for its final landing

July 21, 2011 · Posted in Uncategorized · Comment 
Posted at 08:41 AM ET, 07/21/2011

Video

By 


(Bill Ingalls/AP)


Just before sunrise, the space shuttle Atlantis made its final landing, putting to bed the 30-year U.S. shuttle program. “Like a UFO in the dark, fiery contrails lighting Florida up,” Beth Carpenter wrote on Twitterin one of the many elegies.

The NASA Goddard Photo and Video team put together a short, sweet tribute to the last flights of Discovery and Atlantis. In the first few seconds, Discovery moves past the night side of the Earth into the daytime, as the Aurora Borealis clings to Earth’s side. In the second, the Discovery shuttle moves over a cloudy United States. And in the last few moments, the sun rises behind Atlantis in this time-lapse sequence on July 19, 2011, just two days before it landed:

(Watch the video here)

 

By Melissa Bell  |  08:41 AM ET, 07/21/2011

http://www.washingtonpost.com/blogs/blogpost/post/atlantis-comes-in-for-its-final-landing-video/2011/07/21/gIQAwJVcRI_blog.html

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