Engineering

Part 1 - Engineers 1

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Thank you for reading, voting, following and adding, 'ENGINEERING' to your reading list or library.    Dunc MacPhun 2022 March 25.

The first engineer on record is Imhotep, the reputed architect of Djoser's step pyramid, built about 2630–2610 BCE but there are many earlier engineers such as the unsung genius who invented the shaduf (a counter weight on a lever slung from tree, used to lift water up to an irrigation channel).

The term engineer dates back only to 1325 CE, and it originally meant a constructor of military engines such as the catapult. The word engine comes from the Latin ingenium, meaning a clever invention.  But early engineers devised ways to make tools and reduce work using material they found in their neighbourhood and extracted metals from ores.

Much later, natural philosophers observed the work of artisans and tried to explain what they found but it was not until the middle ages that some chemists began to systemically use the scientific method and not until the 19th century that William Whewell coined the word scientist.

 Archimedes of Syracuse (287 - 212 BCE) was one of the first to apply mathematics to physical phenomena and is credited with machines, such as his screw pump, compound pulleys, and defensive war machines. 

Hero (or Heron) of Alexandria (10 - 70 CE) invented the first steam turbine and was associated with a piston-in-cylinder, force pump widely used as a fire engine pump in Roman times.

The René Descartes designed an experiment to determine atmospheric pressure as early as 1631. In 1654, Otto von Guericke developed a piston vacuum pump to extract the air from a closed container. His most famous experiment occurred in 1657, when he put two 20-inch diameter hemispheres together with a vacuum seal and pumped most of the air out of the enclosed space. The air pressure outside held the hemispheres together so tightly that they could not be pulled apart by two teams of horses.

In 1638, Galileo, pondering as to why some syphons would not work, suggested an experiment. Raffaele Magiotti and Gasparo Berti filled a long tube, sealed at both ends, with water. They then stood the tube upright in a basin already full of water. When they removed the bottom plug, some of the water poured out into the basin and, when it stopped, the level of the water inside the tube stayed at exactly 10.3 m (34 ft) above the basin.

In 1643, one of Galileo Galilei's students, Evangelista Torricelli, had the novel idea that it was not a vacuum that kept the water in the sealed tube but the weight of the atmosphere and invented the mercury barometer that was used to prove that air pressure was less at higher altitudes.

 In1690, Denis Papin, after working with Christiaan Huygens and Robert Boyle, built a model piston steam engine and, in 1705, he developed a larger steam engine (based on an invention by Thomas Savery) with the help of Gottfried Leibniz. It used steam pressure and it was used to power the first steam-powered vehicle of any kind, a paddle wheel driven ship. Papin's work may have influenced Thomas Newcomen's atmospheric engine built in 1712.

In 1689, Papin suggested that a forced air pump could maintain the pressure and fresh air inside a diving bell, allowing men to work underwater. Engineer John Smeaton used this idea 1789.  In a 1759 paper, Smeaton, studying the wings of windmills, developed the concept of a lift equation and the Smeaton coefficient. The Wright brothers later found this was in error and used a wind tunnel to correct it.

In 1662, Robert Boyle used a J-shaped glass tube, to compare the pressure and volume of a gas. The tube was sealed at the short end and partly filled with mercury so that a fixed quantity of air was trapped in the short end of the tube. By adding mercury Boyle could measured the pressure of the gas from the difference levels of the mercury in the two ends of the tube, and he could measure the volume of the gas in the short end. Thus proving that the volume was halved if the pressure was doubled and vice versa. In 1663, King Charles II named Boyle as a founding member of the Royal Society of London.

 Gas laws

Boyle also discovered that air was needed to propagate sound and that ice had a larger volume than the original volume of water, explaining why ice floated in water. 

 Robert Hooke built vacuum pumps and experimented with gas laws while he also built telescopes and, in 1665, inspired the use of microscopes with his book, Micrographia. Based on his microscopic observations of fossils, Hooke was an early proponent of biological evolution. He suggested that air contained a substance necessary for combustion and that air was made of small particles separated by relatively large distances and proposed, correctly, that heat was the manifestation of faster movement of the particles of matter. He hypothesized that the motion of the planets was governed by a gravitational inverse square law and came close to an experimental proof, an idea that was developed by Isaac Newton.

 Elasticity

Hooke discovered the laws of elasticity and designed a balance spring for watches that was an essential feature for the precise clocks needed to find longitude at sea. Hooke also introduced the pendulum for clocks. He was the first to suggest that matter expanded when heated, and was also involved in the design of a machine to cut teeth on watch gears much finer than could be done by hand. After the Great Fire of London in 1666, he was appointed Surveyor to the City of London. Hooke's planning still influences London today and his ideas of building wide boulevards on a grid pattern were subsequently used in the renovation of Liverpool and Paris.

Among his many achievements, Isaac Newton published his work on the three universal laws of motion in 1687. 

1. An object remains at rest or moves at a constant velocity until an external force is applied.

2. the force applied is equal to the mass of an object multiplied by the acceleration. (Force = mass x acceleration). Thus, if you double the force, you double the acceleration, and, if you double the mass, you cut the acceleration in half. Mass is the weight divided by the gravitation acceleration. (On the Earth's surface, the free fall acceleration in a vacuum averages 9.8 m/s2 (approximately 32.2 feet/second squared)). Acceleration is feet per second per second, meaning that an object falling, in a vacuum, under Earth's gravity alone will accelerate to a velocity of 32.2 ft per second every second. After one second it will have velocity of 32.2 ft per second and after two seconds the velocity will be 64.4 ft per second etc.

3. When an object applies a force to a second object, the second object exerts an equal force in the opposite in direction. (To every action there is an equal but opposite reaction). Newton used these laws to defined the law of universal gravitation, accurately explaining the solar system. (Incidentally, he coined the term gravity from the Latin word gravitas (weight)). Among his many other achievements, he improved mathematics and also devised a calculus for geometrical analysis that proved essential for most subsequent engineering work.

Newton's work contributed to the Industrial Revolution and his laws of motion were not modified until Einstein realized that they did not apply when velocities approached the speed of light, and published the theory of relativity, 200 years later.