energy and mechanics
10. Natural gas (China, 4th Century BC):
When the people of the southern provinces of China located natural gas ormethane on the surface of the soil, its spontaneous combustion must have made them decide to exploit it. A text dating from 347 BC describes the making of water proof bamboo pipes with bitumen. These pipes were used to transport methane to the towns, where it was used for various things along with town lighting. Methane was stored in bamboo tubes and these were used as torches and fuel reserves by travelers. It was during the first century, that the Chinese drilled the earth to collect methane in a systematic way. Methane gas, found on the surface, burned without danger. But it has been seen that the consumption of methane can cause some accidents. To avoid the explosion of methane, the gas collected at great depths though richer, had to be mixed with air before use.
9. Ball-Bearings (Mesopotamia, Egypt, 3000 BC):
The rows of logs used in Mesopotamia and in Egypt to transport heavy objects, such as blocks of stone or boats, can be said to be the principle behind the invention of the ball bearings. It consists of balls to reduce the friction between two moving objects at the point of contact. Thus, it was a mechanical principle, evidence of which was found in Greece in the 5th and 4th century BC. It was found in 1928 that a primitive ball bearing mechanism, consisting of a cylindrical case with bronze balls, was invented by Roman engineers. This cylindrical case might have reduced the friction between the metallic objects and the wooden objects. With the advancement of different means of transport, and also due to the advancement of metallurgy in 19th century the interest in ball bearing increased. Ball bearings were installed in 1879, and the first vehicle to benefit from it was the bicycle. In 1862, the Frenchmen Pierre Michaus patented ball bearings.
8. Aerodynamics (Tsiolkovski, 1892 – 96, Chrysler, 1934):
Since the birth of ballistics, problems caused by air resistance of moving objects have been experienced. But it was not until the vehicles moving on the ground, sea and air attained speed, that these problems were heeded. Between 1892 and 1896, Konstantin Eduardovich Tsiolkovski built fan engines, thus, defining mathematically the forces of friction exerted on the surface of the vehicle. But when Aeroplanes, cars and boats were designed, aerodynamics was not taken into account. In 1899 the Belgian Camille Jenatzy designed the vehicle which beat the 100 km/h record. Its chassis was in the form of a shell. Subsequently, Andre Citroen’s 7A, the front wheel drive and the Chrysler Airflow were the first motor vehicles that attempted to reduce the air resistance for the forward motion. Soon the automobile and the aviation industries started giving huge importance to the aerodynamics.
7. Turbines (Hero of Alexandria, 1st century BC, Leonardo da Vinci, 1480):
Turbines were the machines which worked on the hydraulics, gas and steam energy. The success of gas turbines in the 20th century led to thew turbo compressor. In 1480 AD, Leonardo da Vinci attempted to make the hot air turbine which was gas powered, and was called smoke jack. In 1872, the German F. Stolz proposed a turbine consisting of a combustion chamber from which hot air was directed towards a heat exchanger where it was re heated by air coming from another combustion chamber. This was then directed towards the compressor activating a paddle wheel, which in turn would send it out into the open air. Stolz devised the principle of the double cycle open gas turbine, but could not put it into practice as the technology was not advanced at that time. In 1884, Parsons made a turbine in which steam was fed centrally and ejected in all directions. The output of the De Laval turbine was improved independently by the Frenchman C.E.A. Rateau and the American Charles G. Curtis, in 1894.
6. Hydraulic pumps (Archimedes, 3rd century BC, Hero of Alexandria, 1stcentury BC):
Certain mechanisms, which convey water from one level to another and finally draw it up or invert its flow, were developed and improved. One such mechanism – the screw, was made by Archimeded. It consisted of seven partitions fixed in a spiral form on a log so as to create the same number of compartments. From a streamlining effect it was covered with a cylinder, and coal tar was used to make it water tight, leaving the only two ends open. The foundation for modern pumps was laid with the pneumatic organ made by Ctesibius, and engineer from the school of Alexandria. The device consisted of two cylinders with a hole made on their lower surfaces. The pistons were activated by rods fixed to a balancing rod. The two cylinders were connected to each other by a horizontal pipe, to which the drainage pipe was connected. Hero of Alexandria worked and improved upon this above mentioned principle. He attached a head to the drainage pipe which could rotate completely in a circle, that is, full 360 degree. Thus allowing water to be made available in all directions. He also reinforced the water tightness of the cylinder by making disc valves for the input of water.
5. Fuel cell ( Bacon, 1959):
In a fuel cell, reactions which produce electric current are brought about by the substances present outside the casing. Its main advantage is that it provides continuous current. In 1959, the Englishman, Francis Bacon built the first specific fuel cell. It consisted of an alkaline electrolyte potassium hydroxide dissolved in water. The electrodes are made up of a porous metal, into which the electrolyte can only penetrate in a controlled manner. Behind one electrode plate there is oxygen, and behind the other electrode plate is hydrogen. When hydrogen comes in contact with ions of the electrolyte, in the pores of the corresponding electrode, some electrons are freed. These electrons are captured by the atoms of oxygen on the other side. Hence the current flows as long as there is hydrogen and oxygen in the reservoir.
4. Electric Generator (Guericke, 1663; Gramme, 1870; Lamme, 1896):
In 1663, Otto Von Guericke had an idea of making a very simple machine producing static electricity. His machine consisted of a sulphur ball on an axle, turned by a crank. When both hands were placed around the ball, the hands were excited electrically. In 1787, the Englishman Edward Nairne made a device which produced negative or positive electricity, but it was of no practical use. In 1831, the Englishman Michael Faraday had discovered electromagnetic induction and his machine began to have a greater output after the Italian Antonio Pacinotti (1860) and the Belgian Zenobe Theophile Gramme (1870) brought about certain improvements. Subsequently, the generators started benefiting from the invention of the internal current equalizers, by the American Benjamin Graver Lamme, in 1896. Thus, generators became large and powerful. As a result, current was produced from steam and hydraulic energy and transmitted over greater distances. Thus, energy became available everywhere.
3. Electric Battery (Galvani, 1780; Fabbroni, 1769; Volta, 1800):
Copper and iron existed during the Parthian period. They might have notice the contractions an animal underwent on being hanged from an iron bar. On plugging copper and iron into a container of acetic acid, electricity was generated. Thus, we may conclude that Volta was inspired to make an electric battery, keeping all these discoveries in mind. In 1780, the Italian Galvani, attached a copper hook to the spinal c0rd of a dissected frog, and then hooked the frog to an iron net. When he touched the animal’s leg nerve with a scalpel, it underwent spasms. Volta, on other hand, understood the implications of Galvani’s experiment. Fabbroni, in 1796, discovered that if two strips of different metals were place in water in such a way that they touched each other, then one of the strip was oxidized. The battery by Volta consisted of several pairs of zinc-copper discs, in direct contact, but separated from one another by moist cardboard.
2. Carnot Cycle (Carnot, 1824):
Sadi Carnot’s invention was a major event because it founded a new science called Thermodynamics. In 1824, Carnot published a report, in which he outlined a theory of the steam engine. According to Carnot, the cylinder which is in contact with a source of heat must be divided into four stages. In the first stage, piston A, due to the expansion of the gas, is at the end of the stroke. It is anisothermic expansion wherein the internal loss of heat is made up by the external source of heat in the decompression. In the second stage, that is from B to C, there is cooling of the gas due to decompression, thus expansion is adiabatic. From C to D, which is the third stage, compression is isothermic and finally from D to A, it is an adiabatic phase. The two expansion stages produce energy and the compression stages use up the energy.
1. Atomic Energy (Einstein, 1907; Hahn, Meitner, Srassman, Bohr, 1939; Fermi, 1942):
The concept of the fission of the atom was first noticed in the work of Albert Einstein, in 1907, where he compared energy and matter (E=mc²). In 1938, the Germans Otto Hahn, Lise Meitner and Fritz Strassman discovered that when uranium was bombarded with slow or fast neutrons, it would break down into two other elements, barium and krypton, with the release of an enormous amount of energy. The peaceful use of atomic energy was realized only when the first atomic bomb was manufactured. This allowed three essential factors to be classified. The first was the nature of the element that could be used to start the energy releasing chain reactions. Bohr found it to be uranium-235 present in small quantities with uranium-238. Plutonium-239, which was discovered later, could also be used for the purpose. The Italian Enrico Fermi built the first nuclear reactor at the University of Chicago in the United States. It functioned with graphite, uranium metal and uranium oxide, with control rods made up of cadmium. The graphite served as a moderator, i.e., helping in slowing down the reaction.
