Modbury High School: Fill & Download for Free

Australia has had school shootings, it’s just that they weren’t covered much in the media. Here is a list from Wikipedia:Orara High School, Coffs Harbour, Australia June 19, 1991- A student brought a rifle to school injuring 2 teachers and 1 student. The shooter was tackled to the ground by fellow students. This was the first known school shooting to occur in AustraliaBanksia Park High School, Adelaide, Australia, March 31, 1993 - A student brought a shotgun and rifle to school. The shooter fired two shots and the school was evacuated. The student remained in the school till coaxed out by police.La Trobe University shooting, Melbourne, Australia, August 3, 1999 - A student opened fire in a La Trobe University campus restaurant that he used to be employed by, killing the restaurant's manager. Other patrons were injured.Monash University shooting, Melbourne, Australia, October 21, 2002 - A student shot his classmates and teacher, killing two and injuring five. It took place at Monash University in Melbourne, Victoria, AustraliaTomaree High School, Salamander Bay, Australia, April 3, 2003 - The shooter threw petrol bombs before opening fire, seriously wounding 2 students.Modbury High School, Adelaide, Australia, May 7, 2012 - A Year 8 student took a revolver on school grounds, firing shots; nobody was injuredSchool shooting - WikipediaAustralia has also had school shootings and they were after 1996

Gee, haven’t we all learned in high school that James Watt invented the steam engine and spurred the Industrial Revolution!I, for one, am glad that you forgot that bit of history lesson, because the actual story is a much more fascinating account human enterprise, and an interplay between markets, technology, and capital.It all began with iron.You see, people had long known about iron ore, and as early as late 15th century, crude iron was being extracted by a process known as smelting[1][1][1][1]. (No rocket science here. You heat the ore till the iron melts and then you pour it out.) What you needed was a sufficiently hot oven and fuel. Charcoal, i.e., half burnt wood was used as the fuel, and bellows were used to deliver additional air to the fuel, thereby raising the rate of combustion. You can think of the metallurgical bellow as a giant version of this.And this is a schematic of the whole process of smelting.Courtesy: Iron processingWhat has this got to do with steam engines, you ask?Charcoal is contaminated with sulfur, which in the course of smelting, blended with the iron ore. The resulting iron, known as pig iron, was brittle. The smelters soon realized this. They also realized that using coke (purified coal, which has a much less concentration of sulfur) as fuel would improve the quality of iron substantially.Mining flourished as an enterprise to cater to the increased demand of iron ore and coke. Shallow mines were horribly dusty and not conducive to business … because you know, the laborers couldn’t breathe. Deeper mines cut down on dust but flooding was a common problem because these were often located below the water line. There was a huge demand for something to pump out water.You see where this is going. Right!Concept of an engine run on steam was not new. Hero of Alexandria constructed (or at least described) aeolipile, the earliest version of the modern steam engine, almost two millennia before the industrial revolution[2][2][2][2].In 15th and 16th centuries, people experimented with boilers to generate steam in a confined space, and the pressure generated would be used to move water through a pipe. These were rudimentary designs. The engines never seemed to work for long, and boiler explosions were commonplace.Where others failed, Edward Somerset (second Marquis of Worcester) succeeded. In 1665, he built a steam engine that actually worked. He improvised a bit and had the steam created in a boiler fill a vessel half filled with water. The steam was then allowed to run out to another cooler vessel, where it condensed back into water. The lower pressure of the escaping steam would create a vacuum that would suck water into the first vessel to replace the steam that left. Unfortunately, Somerset’s engine was only good at moving water. It operated fountains, but had very few other applications.Edward Somerset’s steam-engine । Courtesy: AlamyIn 1680, Huygens conceptualized the gas engine. He figured that an explosion inside a cylinder’s combustion chamber could push a piston up. The explosive force would expand the gas and lift the piston, and would remove all of the air from the cylinder through a set of open valves. The valves would then be closed, and the subsequent vacuum would pull back down the piston.Huygens’ steam engine । Courtesy: ScienceDirectSweet! But it didn’t work, at least not as well as Huygens wanted.But ideas have a curious shelf-life.Denis Papin, one of Huygens’ students and inventor of the “digester” pressure cooker, modified Huygens’ design by filling the combustion chamber with water (Huygens had used gunpowder). A flame boiled the water to create steam, which would lift the piston up. The flame was then removed and the steam condensed, forming a vacuum, which sucked down the piston, and it started all over again.Papin’s engine । Courtesy: ThermodynamicsIt worked. Papin’s cylinder was was 2½ inches in diameter and could lift 60 pounds once a minute. Papin described it in his memoir A New Method to Obtain Very Great Motive Powers at Small Cost[3][3][3][3]. He was one of the first to use the term ‘motive power’ and also gave a crude description of what we now know as the Carnot cycle[4][4][4][4].Thomas Savery of Modbury was familiar with the works of both Somerset and Papin. He combined and improved upon their designs. His “Fire Engine” consisted of Somerset’s two-vessel design, with the addition of a useful cock valve to control the flow of steam between the two vessels. He also ran some of the pumped water over the outside of the vessels to create surface condensation, which helped the steam condense and the engine run faster.[5][5][5][5]Savery’s steam engine. (Reproduced from footnote 5)He marketed it as the “Miner’s Friend.” Miners used it to pump the water out of their mines but the Miner’s Friend was no friend beyond 40 or 50 feet, as the suction was not enough to pull up much water. (Although Savery himself wrote that his “engine at 60, 70, or 80 feet raises a full bore of water with much ease.") Plus, Savery’s engine had a reputation for boiler explosions.Still, the demand was there.Thomas Newcomen of Darthmouth (and fifteen miles down the road from where Savery hailed) created the “Atmospheric Steam Engine” by combining Savery’s surface condensation vessel design with the Huygens/Papin cylinder and piston design.Newcomen’s atmospheric steam engine । Courtesy: Steam Engine HistorySteam would be fed into a cylinder with a boiler, until the piston reached the top. Then the outside of the cylinder was cooled by turning a valve or adding droplets of cold water inside the cylinder. Condensation of steam would create a vacuum and pull down the piston. Instead of pumping water directly with that vacuum, it would move a beam above it up and down. A pump rod attached to the beam would operate a water pump in the mine.[6][6][6][6]Unfortunately for Newcomen, Savery held a patent that covered any steam engine that used this surface condensation method. In 1708, the two men formed a partnership to co-own the patent for this new and improved Newcomen engine. A piston of diameter of 2 feet operated at at six to ten strokes a minute. A small modification by Humphrey Potter improved the speed to 15-16 strokes per minute. Theoretically, Newcomen engine could pump 3500 pounds of water up 162 feet. That’s the power of eight horses.Newcomen engine was a technological wonder in its day, but (there’s always a but) it still was practically only five horse power and it malfunctioned a lot … a lot lot.Enter James Watt.He was tasked with fixing the engine at Glasgow university. He soon identified the problem. Because the Newcomen engine kept blasting cold water inside and on the surface of the cylinder, it wasted a lot of energy used to create the vacuum. Watt theorized that the cylinder had to be kept boiling hot to improve its efficiency. His solution was to create a separate chamber (“condenser”) outside of the cylinder, and kept underwater, as cool as possible.Watt’s engine । Courtesy: Steam Engine HistoryPhysics was sound, but the engineering was shoddy. The condenser did not work optimally because the cylinder was not “cylindrical” enough and the engine leaked steam like crazy. Watt himself constructed a cylinder that was within 3/8th of an inch of being a “true cylinder.” But it wasn’t enough. Nothing was enough. He worked for five years — 1763 to 1767 — to perfect his design.And how was it perfected?There is a saying that wars make the strangest of bedfellows.And war was raging.Brits were fighting the French, the Spanish, the Dutch, and the Colonists in ‘Murica. King George needed guns … big guns. But big guns came with big problems. Higher the gap between the cannon’s barrel and the cannon ball (“windage”), lower the effectiveness of the gunpowder’s blast.John Wilkinson of Shropshire was the man who had perfected the art of making highly effective cannons with a narrow “windage.” His cannons fired higher, farther, and faster. To keep his art secret, he hadn’t even obtained a patent, for he was afraid that some lowly politician would peddle the blueprints of his boring tool for money.But he needed to hurry. It was a huge order, and the King couldn’t wait. He needed something to remove water from his mines and pump his bellows, and he had seen Watt’s engine in action. For all its faults, it was better than Newcomen engine at pumping up the water. What it was not better at was pumping the bellows.Wilkinson was puzzled, and he had paid an arm and leg to have Watt’s engine installed. He dismantled the engine, and figured out the problem. The cylinder wasn’t “true,” but he could make it “true” with the help of his boring tool — the same instrument he used to reduce the “windage” of cannons.Like a true businessman, he told Watt that he could improve his little contraption in exchange for the exclusive rights to supply precision cylinders to his steam engines.So, who invented the steam engine? All these people, and none of them. At the risk of sounding melodramatic, I would just say that it was … time.Footnotes[1] Smelting - Wikipedia[1] Smelting - Wikipedia[1] Smelting - Wikipedia[1] Smelting - Wikipedia[2] Hero of Alexandria - Wikipedia[2] Hero of Alexandria - Wikipedia[2] Hero of Alexandria - Wikipedia[2] Hero of Alexandria - Wikipedia[3] http://www.eoht.info/page/A+New+Method+to+Obtain+Very+Great+Motive+Powers+at+Small+Cost[3] http://www.eoht.info/page/A+New+Method+to+Obtain+Very+Great+Motive+Powers+at+Small+Cost[3] http://www.eoht.info/page/A+New+Method+to+Obtain+Very+Great+Motive+Powers+at+Small+Cost[3] http://www.eoht.info/page/A+New+Method+to+Obtain+Very+Great+Motive+Powers+at+Small+Cost[4] Carnot cycle - Wikipedia[4] Carnot cycle - Wikipedia[4] Carnot cycle - Wikipedia[4] Carnot cycle - Wikipedia[5] Savery Pump[5] Savery Pump[5] Savery Pump[5] Savery Pump[6] Newcomen Details[6] Newcomen Details[6] Newcomen Details[6] Newcomen Details