The Islamic Hegemony Essay Example for Free

The Islamic Hegemony Essay The course of world history could have been altered if a single detail in the events in the 1200’s was changed or did not happen, or a decision was roughly executed at the wrong time, place and situation. Other races or nations may have been the world’s superpower today if the right opportunities were present at that time, and it only means that what could be happening today may be reversed in an instant as not a single nation holds the monopoly of societal change. The world we know today could have been much different if Genghis Khan’s attempt to destroy the Persian Empire was defeated. In the next sections we will present a historical alteration of events and hypothesize on the consequences of Genghis Khan’s defeat with its repercussions on the political, cultural and economic environment of the present. Islamic armies have conquered much of the Central Asian region and converted the population to Islam before the Mongolian invasion of Persia in the 1200’s which halted the Muslim expansion. Whenever these Muslim warriors went, torture, massacre and abuse on the different nomadic tribes, Turkish, Mongolian and other non-Muslim people were perpetuated. The affair on the Silk Road was the only event which altered the course of history. If Genghis Khan was not able to defeat the Persians, it would have been possible that the Islamic Empire expanded East ward without facing any formidable resistance. China in 1279 during the Sung Dynasty has suffered from Mongolian attacks hence any organized resistance would be impossible and the disoriented armies formed to oppose the Muslims would be severely annihilated en masse. The possibility was great that the combined forces of Khwarazmian Empire’s of Shah Muhammad II of Eastern Iran and the Abbasid Caliphate in Baghdad could take hold of the territories that the Mongolian hordes have reached; India, China, Central Asia and farther up in Poland. Without the emergence of Pax Mongolica (Phillips 32), Muslim influence could have reached a vast expanse in Asia, Eurasia and the Caucasus for it was evident that the Muslim armies converted to Islam every nation or kingdom that they had conquered under the scimitar and the green flag. Thus, we would be having two of the world’s most populous nations (China and India) under Muhammad’s doctrines and such could greatly alter the balance of power in the contemporary history. With Islam as the world’s leading religion in terms of the number of believers. The factor that could have attributed to the Islamic success in dispersing its culture and belief is that unlike the Mongolians, who subscribed to the cultures of the conquered lands, they brought along with tem an organized religion and culture paired with iron will to impose their belief and culture by the sword. Later in Kublai Khan’s rule, he had planned to conquer Japan from the Korean Peninsula but was halted when the Mongolian fleet was destroyed by a typhoon. The Mongol leader attacked in 1274 but was unsuccessful due to a hurricane, known to the Japanese as the winds of the Kamikaze. Eight years later, Kublai struck again launching the largest naval brigade prior to the 1700s. However, the Mongol fleet was sunk by another massive hurricane. After these two disastrous failures, Kublai deserted his plans for the conquest of Japan. (Hooker 2) Imagine when the Islamic conquerors have annexed China into the Islamic sphere of influence with the Arabian dynasty on its helm, we would have a Muslim Japan, which is another world superpower today. With the occupation of China and Japan, it would have been easier for the Arab converters to take hold of South East Asian countries like Philippines, Indonesia and the Indochina and monopolize the political and religious power in the region, blocking the European colonial powers from acquiring their colonies (Dutch East Indies, Indochina and Philippines) in the early part of the 14th century. On the other side of the picture, Muslim armies were also waging a war in the Iberian Peninsula, taking Portugal and Spain from their bases in Egypt and North Africa. This could have spelled total disaster for the Christian armies that were also engaged in the Crusades aimed at retaking the Holy Land from the combined armies of different caliphates and kingdoms in the Middle East. This would be greatly altered in the event that the Islamic armies would be concentrated on the expansion in the European kingdoms. Europe at that time was facing constant disputes on its closely knitted states and principalities hence the political atmosphere was not conducive to economic activities. Without trade from the East (mainly referred to the Silk Road) the mercantile economy was paralyzed. The Mongol hordes rampaged Europe with: †¦A massive raid rather than a complete occupation; nevertheless, the picture she paints is chilling. Driving across the North German plain, the same route Cold War planners pictured for a Soviet invasion, the Mongols would have made use of expert reconnaissance to target plunder and grazing land. They would have sacked Belgium and Holland, destroying the embryonic financial centers of Europe. They would have turned south into France, destroying Paris and with it the revival of ancient philosophy that it would have hosted a few decades later. Perhaps they would have crossed the Alps and ravaged Italy, destroying the other birthplaces of the Renaissance†¦The Dark Ages were pure light compared to what could have happened (Dutch) With such factors, the European nations would not be able to reach a stage of economic growth. The Anglo Saxon and European kingdoms were limited to self-preservation and busied with internal conflicts, so if ever the Arabian Empire would pose a threat to the continent, the nations would not be able to respond accordingly. Though these nations were not totally annexed by the Arabian Empire, the age of explorations will not be like what it was in real history. The colonial powers of Europe may have not conquered parts of Africa because of a strong Islamic influence on the continent brought about by the healthy trade relations with the caliphates and emirates in the Islamic world. The Asian continents were already fortified with Islamic sultanates that had ensued from China, which was already an Islamic territory. The discovery of the New World may have not been possible because of the diverted attention of the European nations from exploration to warfare and territorial defense. The effects of these events could have paralyzed the entire European economy as they were scuttling for raw materials for their industries and caused a crisis in the production system making wars of aggression and annexation more often. It should be noted that the Crusades were, hypothetically, defeated by the Muslim armies thus, the Holy Land was in the sole custody of an Islamic state in the Palestine. If that was what had happened, there is a strong probability that the Zionist Israel will not exist therefore a more peaceful Middle East. It was also likely that the strong Islamic states have maintained the sovereignty of their oil resources and subsequently created a more prosperous oil industry free of European influences. Hence, the events that could have transpired in the 1200’s would have created a new world order wherein the Islamic culture is dominant. The majority of the world’s population could have been Muslims and with such superiority in number religious discrimination would be inexistent. It could have been possible that a nation in Middle East is today’s superpower not the United States. Such was the gravity of the alterations in world affairs that even as we speak, we would be subscribing to Arabic-speaking television networks. The dynamism of history is truly fragile. There are many possibilities in the historical development of human societies and each would yield another result. Works Cited Dutch, Steven. The Mongols. (1998). May 23, 2008 http://www. uwgb. edu/dutchs/WestTech/xmongol. htm. Hooker, Richard. The Establishment of the Bakufu. Japan, Korea and the Mongols. May 23, 2008 http://www. wsu. edu/~dee/FEUJAPAN/KAMAKURA. HTM. Phillips, E. D. The Mongols. Vol. 2. New York: Frederick A. Prager, 1969.

Gas metal arc welding

Gas metal arc welding Gas Metal Arc Welding (GMAW) 1 Introduction Welding is the fabrication process of joining two metal pieces permanently by applying heat or pressure or both. Joining takes place by melting and fusing: melting the base metals and applying the filler metal. This is achieved by melting workpieces and adding a filler material to form a pool of molten material (weld pool) that cools to become a strong joint. (Wikipedia) Some advantages of welding are that it produces a strong and tight joining between two pieces, is cost effective, simple and can be mechanized and automated. However welding results in internal stresses, distortions and changes in microstructure in the weld region. GMAW is currently one of the most popular welding methods, especially in industrial environments because it has lead to simplification of the welding process. GMAW is said to be one of the easiest welding processes to learn and perform. This is because in the process, the power source virtually does all the work by adjusting welding parameters to handle differing conditions. GMAW is extensively used in sheet metal industry and automobile industry. It has replaced riveting and resistance spot welding. It has also found applications in robot welding, where robots handle the workpieces and the welding gun to increase the consistency and the manufacturing process rate. The change in welding trends from SMAW to GMAW in the small and medium fabrications, mainly in the automotive industry. The reason is the attempt of manufacturers to maintain quality and decreasing cost.Lateron it was noted that GMAW was not preferred previously because of the limitation of incomplete fusion, which was not preferred for bridge and structural fabrications. However, with increase in the technology in GMAW, such as advancement in pulsed spray mode of transfer of metal, applications of the welding process has increased. Then there were some advancement in pulse metal arc welding by producing spray transfer at low mean currents. In a GMAW, process good thermal and electrical conductivities act as a drawback because such properties lead to excessive heating of base metals. Hence, limiting the use of the gas metal arc welding process. Pulsed gas metal arc welding (GMAW-P) addresses such problems. Another advancement in GMAW is the use of double electrode in the welding proc ess to increase the manufacturing speed. The DE-GMAW allows increasing the melting current while controlling the base metal current at a desired level. They also developed a model to correlate the change in resistance in the base metal required to achieve the desired base metal current. Then came upon the process of laser hybrid welding, which is popular in automotive industry today. They describe the interaction of laser with GMAW during welding and discuss various variables involved during the process. Later on engineers reviewed the droplet transfer models of solid wire. They described the simulation models: SFBT (static force balance theory), PIT (pinch instability theory) and VOF theory. They concluded that results produced by VOF were in confirmation with the experimental results. With advancement in technology of GMAW, its applications have touched new horizon. Therefore, it is important to study about this process in detail. The purpose of this report is to present the process variables, effect of process variables and equipment on the welding process, and sensing and control systems. Advantages, disadvantages and applications of GMAW process are briefly discussed. This report is expected to help future researchers in their research endeavors by acting as a literature review and a guide to the gas metal arc welding process. 2 Methodology This section will briefly describe the types of welding processes and then concentrate on the GMAW process. Different methods of GMAW process, the modes of metal transfer are introduced in this section. Emphasis is laid on the process variables in the GMAW process, equipment used, and the sensing and control systems. In designing a welding process, the effect of different process variables must be considered. Each application has its unique requirements and limitations. These will be in relation to the parameters that can be controlled or not. Also, the equipment used is of great concern in terms of its simple operation and control and uses. It is important to know the process variables that will have affect on the welding process and their relationship with other parameters. The emerging necessity of the welding processes is its automation. With the use of robots in welding, it has become necessary to automate the whole process and monitor and control the operation and quality of weld. Different sensing and control systems under research and recently introduced in the industry are discussed. 2.1 Welding processes Various welding processes have been developed and used in the welding industry depending upon their application, energy source, such as mechanical, electrical, chemical or optical, metals to be welded, location of metals, cost, etc. The three broad classes are: Solid state welding Fusion welding Soldering and Brazing 2.1.1 Solid state welding Solid state weldingis a welding process, in which two work pieces are joined under a pressure providing an intimate contact between them and at a temperature essentially below the melting point of the parent material (Kopeliovich). Two materials bind by diffusion of the interface atoms. The processes that come under this class are: Forge Welding (FOW) Cold Welding (CW) Friction Welding (FRW) Explosive Welding (EXW) Diffusion Welding (DFW) Ultrasonic Welding (USW) Although these processes have advantages, they require thorough surface preparation like degreasing, oxide removal and brushing or sanding. In addition, these processes are expensive. 2.1.2 Soldering and brazin. Soldering and brazing involve melting the filler metal, which then flows into the space between the closely fitted base metals and solidifies. In soldering, the melting point of the filler metal is below 800Â °F while in brazing it is above this temperature. In both these processes, the melting point of the filler metal is below that of base metals. The filler metal is distributed between the properly fitted parts by capillary attraction. Some disadvantages are removal of flux residuals to prevent corrosion, no gas shielding may cause porosity of the joint, large sections cannot be joined, filler materials may contain toxic components and expensive filler materials. 2.1.3 Fusion welding Fusion welding involves the partial melting of two members welded by a heat source and amalgamated into one piece. The thermal energy required for fusion is usually supplied by chemical or electrical means. It may use a filler material like a consumable electrode or a wire. Fusion welding uses a protective layer like gas shielding or flux, which melts and forms a viscous slag on the weld metal that solidifies and removed later. 2.2. Gas metal arc welding (GMAW) Gas metal arc welding (GMAW) or metal inert gas (MIG) welding or metal active gas (MAG) welding is a semi-automatic or automatic arc welding process, which joins metals by heating them to their melting point with an electric arc. A continuous, consumable electrode wire and a shielding gas are fed through a welding gun. MIG involves use of an inert gas while MAG uses active gas like oxygen or carbon dioxide. 2.2.1 GMAW process Gas metal arc welding process usually comprise of a constant voltage, direct current (constant current or alternating current systems can also be used) arc burning between a thin bare metal wire electrode and the work piece. The arc and weld area are encased in a protective gas shield, fed through the welding gun. A continuous, consumable wire electrode is fed from a spool, through the welding torch/gun, which is connected to the positive terminal into the weld zone. 2.2.1.1 Parameters. The parameters of GMAW process are: Shielding gas Electrode size Electric parameter: voltage and current (continuous current is used) Feed rate (of electrode) Travel speed The shielding gas like carbon dioxide or a mixture of carbon dioxide and argon helps protect the molten metal from reacting with the atmosphere. Molten metal when exposed reacts with oxygen, nitrogen and hydrogen in the environment. Shielding gas flows through the gun and cable assembly and out of the gun nozzle with the welding wire to shield and protect the molten weld pool. The risk of reacting of metal with atmosphere limits the use of GMAW indoors because outdoors wind can blow the shielding gas away from the work piece and result in reaction. The consumable wire commonly is copper colored mild steel, which has been electroplated with a thin layer of copper to protect it from rusting, improve electrical conductivity, increase contact tip life, and improve arc performance. 2.2.2 GMAW methods. GMAW can be performed in three different ways: Semiautomatic Welding wire feeding is controlled by the equipment and the movement of welding gun is by hand. Also called hand-held welding. Machine Welding a gun is connected to a manipulator (not hand-held). Manipulator controls are adjusted constantly by an operator. Automatic Welding welds without the constant adjusting of controls by a welder or operator. 2.2.3 Mode of metal transfer in GMAW. GMAW use four different modes to transfer metal from the electrode to the work piece. These are: Globular mode of transfer Short-circuit transfer Globular transfer Spray transfer Pulse-spray transfer 2.2.3.1 Short-circuit transfer Short circuit transfer refers to the welding achieved by short-circuiting (touching) welding wire with the base metal between 90 200 times per second. The wire feed speeds, voltages, and deposition rates are usually lower than with other types of metal transfer such as spray transfer. This facilitates welding thin or thick metals in any position. A typical Short Circuit Cycle can be summarized in following steps: Electrode is short-circuited to base metal. No arc and current is flowing through electrode wire and base metal. Resistance in electrode wire increases causing it to heat, melt and neck down. Electrode wire separates from weld puddle, creating an arc. Small portion of electrode wire is deposited, which forms a weld puddle. Arc length and load voltage are at maximum. Heat of arc flattens the puddle and increases the diameter tip of electrode. Wire feed speed overcomes heat of arc and wire approaches base metal again. Short circuit cycle starts again. 2.2.3.2 Globular Transfer Globular transfer refers to the state of transfer between short-circuiting and spray arc transfer. Large globs of wire are expelled from the end of the electrode wire and allowed to enter the weld puddle. This type of mode of transfer results when welding parameters such as voltage, amperage and wire feed speed is somewhat higher than the settings for short circuit transfer. 2.2.3.3 Spray Arc Transfer Spray arc transfer refers to spraying a stream of tiny molten droplets across the arc, from the electrode wire to the base metal. Spray arc transfer uses relatively high voltage, wire feed speed and amperage values, compared to short circuit transfer. Inert argon rich shielding gas is used for best results. 2.2.3.4 Pulse-spray Transfer In the pulse-spray transfer mode, the power supply is made to cycle between a high spray transfer current and a low background current. It is different from the spray transfer in that it allows the super cooling of the weld pool during background cycle. In each cycle one droplet transfers from the electrode to the weld pool. The low background current allows pulse-spray mode of transfer to weld out of position on thick sections with higher energy than the short-circuit transfer, thus producing a higher average current and improved sidewall fusion. It can be used to lower heat input and reduce distortion when high travel speeds are not needed or cannot be achieved because of equipment or throughput limitations. 2.2.4 Process Variables The process variables of the GMAW affect the welding efficiency and weld quality. These variables either act alone by affecting the final product or they interact with each other and affect weld penetration, bead geometry. It is important to study these variables and have their set limits for a desired welding process and good overall weld quality. The enough penetration, high heating rate and rightwelding profile make the quality of welding joint. These are affected by welding current, arc voltage,welding speed and protective gas parameters. Table 1 shows the effect of different process variables on penetration depth, deposition rate, bead size and bead width. Table 1: Effect of process variables on penetration, deposition rate, bead size and bead width. Welding variables Desired changes to change Penetration Deposition rate Bead size Bead width Increase Decrease Increase Decrease Increase Decrease Increase Decrease Current and wire feed speed Increase Decrease Increase Decrease Increase Decrease Little effect Little effect Voltage No effect No effect Little effect Little effect Little effect Little effect Increase Decrease Travel speed No effect No effect Little effect Little effect Decrease Increase Decrease Increase Electrode extension Decrease Increase Increasea Decreasea Increase Decrease Decrease Increase Wire diameter Decrease Increase Decrease Increase Little effect Little effect Little effect Little effect Shield gas % Increase Decrease Little effect Little effect Little effect Little effect Increase Decrease Gun angle Drag Push Little effect Little effect Little effect Little effect Push Drag a change will occur if current is maintained by wire feed speed. http://products.asminternational.org/hbk/index.jsp The process variables are listed and discussed below: Welding current (electrode feed speed) Polarity Arc voltage (arc length) Travel speed Electrode extension Electrode orientation (gun angle) Electrode diameter 2.2.4.1 Welding current Welding current is the electrical amperage in the power system as the weld is being made. In GMAW constant voltage power sources (voltage) are used, therefore, amperage is thought to be controlled by wire feed speed. Welding current is read from the power source meter or a separate ammeter is often used. The total welding amperage or current supplied to the arc is determined by the wire feed rate, open circuit voltage setting and the slope setting on the welding power source (Figure 1 and Figure 2). The faster the wire feed speed, higher is the welding amperage. However, the wire feed speed only determines the balance between the welding current and the load voltage at the arc. When all other variables are held constant, an increase in welding current results in an increase in the depth and width of penetration, deposition rate, and weld bead size. This makes GMAW arc was made self-regulating. i.e. if the welder pulls the torch away from the workpiece—raising the arc length and arc voltage—the power supply drops the arc current to burn off wire at a slower rate until the preset arc voltage was re-established. If the welder pushed the torch toward the work—shortening the arc and reducing the arc voltage—the power supply quickly raised the welding current to burn off more wire until the preset arc voltage was re-established. 2.2.4.2 Polarity Polarity describes the electrical connection of the electrode (welding gun) with the terminal of a power source. When the gun power lead is connected to the positive terminal, the polarity is designated as direct current electrode positive (DCEP). When the electrode or the gun power is connected to the negative terminal, the polarity is designated as direct current electrode negative (DCEN). When alternating current (AC) is used, the polarity changes every half cycle of 50 or 60 Hz. In GMAW usually DCEP is used because it yields a stable arc, smooth metal transfer, relatively low spatter, good weld bead characteristics and deep penetration for a wide range of welding currents. On the other hand, DCEN results in the molten droplet size tends to increase and the droplet transfer becomes irregular (Figure 3). This increases large grain spatter. Some wires with unique chemical composition have been developed for DCEN, which give excellent results on galvanized sheets. Variable polarity gas metal arc welding (VP-GMAW) is the current trend in the welding industry. Inverter pulse power supplies allow to combine DCEP and DCEN polarities in varying amounts (Figure 4). In their research, Harwig et al. (2000) showed that VP-GMAW could be used for welding thin gage aluminium sheets. They noted that during DCEN polarity, droplet formation takes place and it is transferred across the arc by DCEP polarity. They said that DCEN could be added up to 60 % to the current, beyond that the arc becomes unstable. 2.2.4.3. Arc Voltage Arc voltage is the amount of voltage present between the electrode and workpiece. Arc voltage and arc length are used interchangeably. Arc voltage is an approximate means of defining the physical arc length in electrical terms. However, one physical arc length could yield different arc voltage readings, depending on factors such as shielding gas, current, and electrode extension. If all these variables are kept constant, arc voltage and arc length can be correlated i.e. with increase in voltage setting, arc length increases. The welders are interested in arc length, but arc voltage is easy to monitor and must be specified in welding procedures. Therefore, its the arc voltage that is most commonly used term than the arc length. Arc voltage controls the height and width of the weld. Any increase in arc voltage from specific value, flattens the bead and increase the width of the fusion zone. Very high voltage results in porosity, spatter (unstable arc), and undercut. However, a voltage less than required will result in narrower weld bead with higher crown i.e. wire stubs on the work. Therefore, voltage must be set midway between high/low voltages. 2.2.4.4. Travel speed is the speed at which a welder moves the electrode along the joint to make a weld. Technically its the linear rate at which the arc is moved along the weld joint. Weld penetration is always maximum at intermediate travel speed, when all other conditions are constant. If low travel speed is used, the arc will impinge on the molten weld pool than working on the base metal and hence affect penetration efficiency. Large increase in travel speed will result in less thermal energy on the base metal. At high speed, the rate of melting of base metal is increased first and then decreased. If travel speed is increased any further, undercutting along the edges of weld bead may occur because of insufficient deposition of filler metal in the path melted by the arc. High speed GMAW as signifies uses high travel speeds. Rapid Arc Company uses pulsed GMAW for faster travel speeds, low spatter, out of position operation and lower heat input. They achieve high travel speeds by using lower arc voltage i.e. shorter arc length, this reduces spatter and washed out bead profile, allowing high torch travel speed. They divided rapid waveform into four parts (Figure 5): Pulse: A sudden increase in current increases arc energy, and forms and squeezes a molten droplet extending from the end of the electrode. Puddle Rise: The ramp down of current relaxes the plasma force, depressing the puddle, allowing it to rise up towards the droplet. Short : The arc collapses, and the droplet contacts the weld puddle. Puddle Repulsion: immediately following a short breaking into an arc, a gentle plasma boost pushes the puddle away and conditions the electrode tip. This ensures reliable separation of the wire tip and the puddle resulting in a stable rhythm of the cycle. 2.2.4.5 Electrode orientation Electrode orientation is the angle of the electrode axis with respect to the travel direction. This is called the travel angle. On the other hand, it could be the angle of the electrode axis with the work surface. This is called the work angle. When the electrode points in a direction opposite to the travel direction, it results in a trail angle and is called the backhand welding technique. When the electrode points in the direction of travel, it results in a lead angle and is called the forehand welding technique. The maximum penetration is achieved for trailing travel angle between 5 to 15Â ° (from perpendicular). This also provides a narrow, convex surface configuration and shielding of the molten weld pool. However, the leading travel angle provides the welder better visibility and a flatter weld surface. This is more commonly used technique. For materials such as aluminum, a leading angle is preferred, because it provides a cleaning action ahead of the molten weld metal, which promotes wetting and reduces base-material oxidation. This is because the leading angle of the electrode pushes the molten metal and slag ahead of the weld. When producing fillet welds in the horizontal position, the work angle should be about 45Â ° to the vertical member. 2.2.4.6. The electrode extension The distance between the last point of electrical contact (usually the gun contact tip or tube) and the end of the electrode. An increase in the amount of this extension causes an increase in electrical resistance. This, in turn, generates additional heat in the electrode, which contributes to greater electrode melting rates. Without an increase in arc voltage, the additional metal will be deposited as a narrow, high-crowned weld bead. The optimum electrode extension generally ranges from 6.4 to 13 mm for short-circuiting transfer and from 13 to 25 mm for spray and globular transfers. 2.2.4.7. The electrode diameter Influences the weld bead configuration. A larger electrode requires a higher minimum current than a smaller electrode does to achieve the same metal transfer characteristics.Higher currents, in turn, produce additional electrode melting and larger, more-fluid weld deposits. Higher currents also result in higher deposition rates and greater penetration, but may prevent the use of some electrodes in the vertical and overhead positions. 2.2.5 Equipment The basic assembly of GMAW containing the components of equipment can be seen in Figure 6. It is important to study each part of the equipment to reach the required quality of the weld. Each application of GMAW will have a specific requirement for each part. Therefore, these can be controlled or modified to change the welding process to achieve good welding efficiency and quality. The fundamental equipment for a typical GMAW installation includes: Welding gun Electrode feed unit Welding control mechanism Power source Electrode source Regulated Shielding gas For automatic welding equipment the wire feed unit and the current contact and gas barrel are combined in a single welding head (Figure 7). For Semi automatic welding flexibility is generally achieved by separating the wire feed unit from the torch and passing wire, gas, current and cooling water through the flexible conduit. Wire-feeding complexities must be considered using these systems. High powered motors are required to push wire for several yards. Ferrous metal wires can be fed through smooth, flexible and rigid spiral steel wire-feed tubes. But, aluminium and non-ferrous metals are difficult to feed through tubes until they are nylon lined. The wire feed difficulties increase with decreasing wire diameter. Welding current in GMAW equipment is introduced to the wire by passing it to a copper tube. A variation in point of current pick up can alter the resistance between contact and arc and cause variations in burn-off rate because of its effect on overall circuit resistance. With high currents or high resistance metals the current contact tube is shortened or fitted with small tip diameter tip to reduce variation. Water cooking is required for equipments that have automatic welding heads and those that work at about 250 A. Water cooling and chromium-plated surface make removal of fume and spatter from the nozzle easier. POWER CABLE (NEGATIVE) POWER CABLE (POSITIVE) WELDING VOLTAGE CURRENT DETECTION 115 VAC IN TO PRIMARY POWER 230/460/575 V COOLING WATER IN SHIELDING GAS IN TO CARRIAGE DRIVE MOTOR 115 VAC IN TRAVEL START/STOP WIRE FEED MOTOR SHIELDING GAS IN COOLING WATER IN COOLING WATER OUT The parts of GMAW are discussed below in detail. 2.2.5.1Welding gun Responsible for delivering the electrical current to the electrode, and directs it to the work piece and allows the flow of shielding gas to the weld area. The choice of welding gun is critical, but often ignored over power source, wire feeder, and shielding gas, which are most costly. Proper choice can give good welds and productivity. Different types of guns are used for different applications: heavy duty guns for high current and high volume production, and light guns for low current and out of position welding. Figure 8 shows the most commonly used gun, which is air cooled. Water cooled gun is used for high current requirement. Welding guns are rated on their current-carrying capacity. If inert gas is used, the gun rating is reduced to a much lower extent. A welding gun can be equipped with its own electrode feed unit. Parts of welding gun Back end is the power pin that connects the gun and power cable to the wire feeder. This connection must be tight. A loose connection between the gun and the feeder can cause electrical resistance throughout the entire system. This will result in overheating, which may damage the gun or the wire feeder. This may also cause gas leakage and poor conductivity that can lead to an erratic arc and poor weld quality. Usually a supportive strain relief is provided at the connection between the power cable and wire feeder. This helps in good wire feeding, which results in a stable arc and quality welds. There is another option of selecting a gun with multiple feeders for various GMAW applications reducing overall cost. Contact tube: is used to transmit welding current to the electrode and to direct the electrode towards the work. It is usually made of copper or a copper alloy and connected electrically by power cable to the power source. The tube hole for wire input is of 0.13 to 0.25 mm larger than the wire being use, larger for aluminium and non ferrous metals. Nylon lining is used for non ferrous metals and aluminium electrodes. This inner surface of the tube has to be changed in case of excessive wear, which may result in poor electrical contact. Consumables (nozzles and tips): The nozzle in the welding gun directs the shielding gas into the welding area. An even flow must be maintained to protect molten weld from the environmental gases. Larger nozzles are used for high current work with large weld pool and small nozzles used for low current work. Consumables are selected based on longevity instead of price. This reduces costs of replacement parts and changeover time. Non-threaded, large-base contact tips that fit securely to the diffuser provide good electrical conductivity and heat transfer. It is important to use heavy-duty tips and nozzles that provide good gas coverage to help ensure good arc starts, less spatter, and less rework and cleanup. Electrode conduit and liner support: protect and direct the electrode from the feed rolls to the gun and contact tube. They are connected to a bracket adjacent to the feed rolls on the electrode feed motor. It is necessary to maintain uninterrupted electrode feeding for good arc stability. The liner is the most critical component of the GMAW gun because of the problems that can arise from it. A steel liner is used for steel and copper electrodes, whereas nylo

Sound Waves Essay -- physics acoustics sound

What is a sound wave? A sound wave is produced by a mechanical vibration, such as a tuning fork. The vibrating object causes the surrounding medium, such as air, to vibrate as well.The wave travels through the medium to a detector, like your ear, and it is heard.As with any type of wave, a sound wave is also described by it's wavelength, amplitude, period, and frequency. WAVELENGTH is the distance from one point on the wave, to the next identical point, or the length of one part of the wave. AMPLITUDE is the distance from the midpoint to the place of maximum displacement. FREQUENCY is the number of cycles that occur in one second. It is also the inverse of the period. PERIOD is the time it takes for a wave to complete one full cycle. It is also the inverse of frequency. Sound waves are longitudinal waves that consist of high and low pressure areas called condensations and rarefactions, respectively. Since sound waves are longitudinal waves, the particles of the medium oscillate parallel to the velocity of the wave. The individual particles do not travel along the wave. They only oscillate back and forth and the wave still propagates through them. The speed of sound depends on the type of medium that the wave is traveling through. In air, the speed of sound is about 340 m/s or 760 mph for a normal spring day. The speed also depends on the temperature of the medium. The formula used to figure out the speed of sound, in air, on any given day is; v = 331 m/s + 0.6T where v is the velocity of the wave, T is the temperature of the air in degrees celcius, 331 m/s is the speed of sound at 0Â °C, and 0.6 is just a constant. So as the temperature increases, so does the speed o... ...99. Health Issue of the Month: Middle Ear Infection. March 1999. 12 Apr. 2003. Sight and Hearing Association. Hecht, Eugene. Physics: Algebra / Trig. 2nd ed. Brooks/Cole, 1998. Henderson, Tom. Sound Waves and the Eardrum. 17 Aug 1998. 10 Apr 2003. Kurtus, Ron. Sound Waves. 18 Feb 2002. 10 Apr 2003. Russel, Dr. Dan. Longitudinal and Transverse Wave Motion. 12 Apr 2003. Serway, Raymond A. and Robert J Beichner. Physics for Scientists and Engineers. 5th ed. Brooks/Cole, 2000.

Our Young Folks - An Ethical Guide for Children :: Our Young Folks

Our Young Folks - An Ethical Guide for Children Our Young Folks was a children’s magazine that ran from 1865 until 1873. Although the magazine didn’t last long, it was widely read by children across the country and even abroad, and circulation eventually exceeded 75,000 (Kelly 345). The magazine began publication just four months before the end of the Civil War, and during this time of upheaval Our Young Folks was an ethical guide for the nation’s children. Nearly every story offers the reader a moral, and children were continually urged to put others before themselves. Selfless Models One of the ways Our Young Folks gave its readers moral instructions was by setting examples. The magazine was packed with stories of selfless children who lived and died for others. Such characters were held up as models for how the young readers of the magazine should behave. One of these selfless stories is â€Å"My Heroine,† which is a poem about a young girl who dies while protecting her baby. Stanzas six and seven clearly outline the child’s heroism: Her mother gave the piteous tale: â€Å"How that child’s courage did not fail, Or else poor baby-† She stopped, pale, And shed tears without number; Then told how at the fireside warm, Lizzie, with baby on her arm, Slipped- threw him from her- safe from harm, Then fell- here in her slumber.    Lizzie shrieked, â€Å"Take him!† and uptossed Her poor burnt hands, and seemed half lost, Until a smile her features crossed, As sweet as angels’ may be. â€Å"Yes, ma’am,† she said, in feeble tone, Our Young Folks - An Ethical Guide for Children :: Our Young Folks Our Young Folks - An Ethical Guide for Children Our Young Folks was a children’s magazine that ran from 1865 until 1873. Although the magazine didn’t last long, it was widely read by children across the country and even abroad, and circulation eventually exceeded 75,000 (Kelly 345). The magazine began publication just four months before the end of the Civil War, and during this time of upheaval Our Young Folks was an ethical guide for the nation’s children. Nearly every story offers the reader a moral, and children were continually urged to put others before themselves. Selfless Models One of the ways Our Young Folks gave its readers moral instructions was by setting examples. The magazine was packed with stories of selfless children who lived and died for others. Such characters were held up as models for how the young readers of the magazine should behave. One of these selfless stories is â€Å"My Heroine,† which is a poem about a young girl who dies while protecting her baby. Stanzas six and seven clearly outline the child’s heroism: Her mother gave the piteous tale: â€Å"How that child’s courage did not fail, Or else poor baby-† She stopped, pale, And shed tears without number; Then told how at the fireside warm, Lizzie, with baby on her arm, Slipped- threw him from her- safe from harm, Then fell- here in her slumber.    Lizzie shrieked, â€Å"Take him!† and uptossed Her poor burnt hands, and seemed half lost, Until a smile her features crossed, As sweet as angels’ may be. â€Å"Yes, ma’am,† she said, in feeble tone,

A Comparison of Things Fall Apart and Julius Caesar Essays -- comparis

Comparing Things Fall Apart and Julius Caesar      Ã‚  Ã‚   "Things Fall Apart" by Chinua Achebe and "Julius Caesar" by William Shakespeare are two very different books that are interrelated through their similar themes and characters. There are characters from both stories that can connect to one another through their common motives and characteristics. Many of the main themes and elements of the stories are similar including a tragic ending and themes of betrayal, honor, and conflict. However, there are differences between the characters and themes from the two books as well.    In Things fall apart, Okonkwo would resemble Caesar most because they were both men of high titles with success in war and battle. Okonkwo was a well accomplished soldier known for the many heads that he had severed off enemies during tribal conflicts. Casesar was one of the greatest generals of all time bringing Rome to its peak height of power. Both men did not fear death but meet death abruptly. Even though they were very similar, Caesar was killed by an assassination, while Okonkwo commits suicide.    Mr. Kiaga, the translator and negotiator for the Christian missionary can be matched most easily to Antony. Both men had great oratory skills which they put to good use. Kiaga used his skills to convert and had won many converts to the new faith. Antony used his oratory skills to convince the crowd at Caesar's funeral that Brutus and the conspirators had killed Caesar unjustly. Both men had very loyal qualities. Antony was loyal to Caesar and wanted to avenge Caesar's death. Mr Kiaga was loyal to the church and Mr Brown, the priest and head of the missionary. Even though they are similar in many ways, they have differe... ...ad done nothing at all and Brutus killed him because he believed that the general would change into a tyrannical ruler. Caesar's ambition could have destroyed Rome if it wasn't for the noble actions of Brutus.    Even though these two books may seem very different, they also share many similarities. Though they are not related through their plots, they definitely share some very important themes and resemblance of characters. Through these similarities, two different stories in completely different time frames and locations can be brought together in many instances.    Works Cited:    Achebe, Chinua. Things Fall Apart. 1958. The Norton Anthology of World Masterpieces, Expanded Edition, Vol. 1. Ed. Maynard Mack. London: Norton, 1995. Shakespeare, William. Julius Caesar. Ed. Alan Durband. London: Hutchinson & Co. Publishers Ltd., 1984.

Demonstrate the persistence of Wordsworthian ideal of country folk Essay

Demonstrate the persistence of Wordsworthian ideal of country folk, childhood and natural education in the two texts that you have chosen. Critical Essay by Rachel Gowland. Wordsworth, as a poet of the romantic era, had several themes, which contribute to this title. This essay will be looking at these themes and discovering whether they have any relevance in the texts studied. These are, the Secret Garden and Goodnight Mr Tom. The preference for rural life and its people was at the height of fashion at the time of Wordsworth. Social reformers such as Rousseau talked about the â€Å"noble savage† and the rustic idyll was an accepted theme for artistes and poets alike. While the social revolutions may have changed by the time the texts were written, the ideals are still continued to some degree. Wordsworth had many sympathies with the victims and vagrants that wandered in the cities and the countryside. Many of his short poems were portraits of simple rural people, intended to illustrate the nature of these folk and their basic wisdom. Poems such as Michael (1880) have the characters almost fused with their natural surroundings. In Michael, patience and tenderness are the key features of the old man’s character. There is strength and a â€Å"natural affinity to the hills and fields in which he lived and worked.† 1 The Secret garden is almost a glorification of rustic folk and their simple way of life. Mary Lennox first encounters Martha, who gives her glimpses of a simple life quite alien to her. â€Å"There’s twelve of us an’ my father only gets sixteen shilling a week. I can tell you my mothers put to it to get porridge for ’em all. They tumble about on th’ moor an’ play there all day an’ mother says th’ air of th’ moor fattens ’em.† (Page 32) 2 Through Martha, she begins to emerge from her egotistical former self. She starts to think about others rather than herself. â€Å"Thank you. She said it stiffly because she was not used to thanking people or noticing that they did things for her† (Page 71) 2 Martha appears a particularly content and dignified individual, who takes pride in her work and her family. She treats Mary as an equal in many ways and is amazed by Mary’s colonial pride. Martha’s plain good sense is treated with respect throughout the book and her dialogues with Mary often bring about great changes in her young charge’s attitudes. â€Å"It was not the custom that Mistress Mary should do anything but stand and allow herself to be dressed like a doll, but before she was ready for breakfast, she began to suspect that her life at Missthlewaite Manor would end by teaching her a number of things quite new to her.† (Page 32) 2 Martha’s is described as an â€Å"untrained Yorkshire rustic† who was not trained to be subservient and had no notion that she should be. In this way she becomes an emboldened character, who helps Mary to grow through her plain sense. Martha was obviously trained well by her mother who also is a rustic woman. She is almost the guiding hand in the background, helping Mary, and later Colin, to transform. Her wisdom shines through Martha and Dickon and all the principles held in family life. Hers is the good mother, the mother earth in Wordsworth’s poems. The respect for her and her kind shines through in the text as it does in the poems, through the voice of the narrator. She is again a considered equal in the narrator’s eyes to all who she comes into contact with. This makes it possible for her to contact Colin’s father and speak to him about his charges. † I sent for you today because Mrs Sowerby said I ought to see you. † (Page 112) 2 The idea of simple sense and country wisdom is proved right in the text. It is the uneducated, untrained folk in the text who can see through the external ugliness of Mary and Colin’s characters to the beauty that lies beneath. And it is the country folk who unlock these children from their past to an almost redemption. This celebration of rural life and the people can also be seen in Good night Mr Tom. The events that occur in Will’s life in the city are overcome by the calm everyday life of the country and its folk. The main character in Wills life is Tom who exudes this country wisdom and good sense. Will takes to heart Tom’s thoughts when persevering with a new task like learning to ride a bicycle. He could hear his Dad’s words over and over again in his head. † Takes yer time, everythin’ ‘as its own time†. (Page 291) 3 Tom guides Will through his life events, helping him to come to terms with all that life throws at him. This is in marked contrast to the ideas of the psychologist, Mr Stelton, whom they both encounter in the hospital when Will is rescued. Tom’s ideas of healing through fresh air, hard work and simple country life are in conflict with the ideas of analysis and treatment. Even the appearance of Tom as a gruff, solid but warm-hearted individual is different to the description of Mr Stelton. â€Å"Tom was well into his sixties, a healthy robust, stockily built man with a head of thick white hair.† (Page 10) 3 In contrast to â€Å"The man was going bald and the hair that remained was of a thin texture. His skin was as white and shiny as a cloistered nun. He gave Tom a bland smile.† (Page 217) 3 The psychologist’s educated ideas appear foolish in response to Tom’s good sense. As in The Secret Garden the figures of authority and city education are made to look ignorant in response to the wisdom of characters such as Mrs Sowerby and Tom. The characters in the village of Little Weirworld are full of warmth and sincerity, with a genuine sense of community that includes everyone in their midst. Their simple pleasures and way of life helps them maintain a sense of calm dignity and practical sense, even in time of crisis. When Mrs Hartridge received a telegram, it was with care and concern that the villagers arranged for someone to be there when she received it. This contrasts sharply with the lack of interest shown by the people in the district where Will originally came from. â€Å"She keeps herself to herself. Bit of a madam. Thinks she’s a bleedin’ saint if you’ll excooth me languid. She does night shifts so I don’t never see her. I live next door yer see. Mind you, I don’t arf hear some funny noises. Very funny.† (Page 203) 3 Tom is ridiculed by the city folk for his accent and intention, but they appear very flippant and foolish when the full story is uncovered. â€Å"I’d like to git my hands on that women†, the warden growled furiously. His pride had been shaken badly. It was embarrassing to have them think he didn’t know his job.† (Page 207) 3 Again, it is the simple country folk in the text who can see through the external ugliness and weakness to the beauty that lies beneath. And it is the country folk who unlock Will from his past. Wordsworth and his contemporaries, viewed childhood as a time of great innocence and joy. A time when new experiences are welcomed and emotions and senses are at there most responsive There was a time when meadow, grove and stream The earth and every common sight, To me did seem Apparelled in celestial light, The glory and freshness of a dream. (Line 1-5) 4 They viewed the child as a redeemer of the adult with their innocence and freedom of mind and spirit. In the Secret Garden, the children can be seen to hold the key to all wisdom. Martha plays an important part in helping Mary to grow into a whole human being. â€Å"He wouldn’t like me.† Said Mary in her stiff, cold little way. No-one does.† Marta looked reflective again. â€Å"How does tha’ like thyself?† (Page 61) 2 In the same way Mary then passes on her newfound wisdom to Colin and they both look to Dickon to expand their experience. It is Dickon who becomes the real redeemer. He exudes healthy childhood wholesomeness. â€Å"A boy was sitting under a tree, with his back against it. He was a funny looking boy about twelve. He looked very clean and his nose turned up and his cheeks were as red as poppies and never had Mistress Mary seen such round and such blue eyes in any boys face.† (Page 92) 2 He makes Colin believe that he can get well and walk. His positive calm attitude clears the gloom from Colin’s mind and he begins to believe in himself. â€Å"When tha’ stops bein’ afraid tha’lt stand on ’em,† Dickon said with renewed cheer. â€Å"An’ tha’lt stop bein’ afraid in a bit.† (Page 206) 2 Once Mary and Colin finally learn to become children again they can then redeem Colin’s father. He begins to wonder whether he can have a relationship with his son but has many doubts. Colin changes this by becoming a positive character that is not afraid of the future or his health any more. In this way he heals himself and also his father. â€Å"It seemed actually like the laughter of young things, the uncontrollable laughter of children who were trying not to be heard.† (Page 272) 2 And â€Å"He said it all so like a healthy boy-his face flushed, his words tumbling over each other in his eagerness- that Mr Craven’s shook with unbelieving joy.† (Page 274) 2 The child as a redeemer can also be seen as a theme in Good Night Mr Tom. Will looks at Tom through the eyes of a child and as such does not see the gruff exterior that the villagers have seen for the forty years since his wife died. Will brings memories of his wife flooding back but with them comes healing. â€Å"Tom stood behind him and stared over his head into the shop. He remembered how Rachel used to spin with delight in there.† (Page 57) 3 Tom learns how to socialise again through necessity and becomes a member of the village community once more. Mrs Fletcher looked steadily into his eyes. His forehead had lost its old furrowed look. The deep pitted wrinkles had softened outwards. Behind his scowling manner was a kindly old man and if it hadn’t been for the arrival of a rather insipid little boy, she might never have known, nor might anyone else for that matter.† (Page134) 3 He responds emotionally to Will in ways that have been closed off for a long time. â€Å"He called me Dad,† he whispered croakily into the darkness. † He called me Dad.† And although he felt overwhelmed with happiness, the tears ran silently down his face. † (Page 288) 3 In the same way, Will has his own redeemer in the shape of Zach, who teaches him to like himself and believe in his own abilities. As Martha and Dickon, Zach is a positive thinker who believes anything is possible. Will had lived all his life with criticism and blame, and Zach and Tom gave him back his self-esteem. â€Å"Willie almost dropped the clod of earth he was holding. No one had ever said they liked him. He’d always accepted that no one did. Even his mum said she only liked him when he was quiet and still. For her to like him he had to make himself invisible.† (Page 77) 3 In this way both Mary Lennox and Will are similar, in that they have to learn to love themselves before they can be loved in return or learn to respond to others around them. It seems clear that the theme of natural education is persistent in both texts. In the Secret Garden there is a distinct lack of formal education in all the children encountered. Mary had a series of governesses but learnt by her own volition, because she chose too. Her education almost begins again when she reaches Misstlethwaite Manor. Through Martha and Dickon she learns how to explore, imagine and play. She begins to discover the simple pleasures of play. â€Å"The skipping rope was a wonderful thing. She counted and skipped, and skipped and counted, until her cheeks were quite red, and she was more interested than she had ever been since she was born.† (Page 71) 2 At first alone and then with Colin she explores the garden and her curiosity and thirst for knowledge begins. The awakening of the garden itself mirrors her awakening. They learn through this almost holistic approach, that through the garden and nature they become physically, socially and emotionally aware. Again it is Dickon who inspires them with his positiveness and his knowledge. Dickon, has little formal education but has a wealth of knowledge which appears to be much more useful than the facts leant in a classroom. He is a pure Wordsworthian invention. â€Å"Do you understand everything birds say?† said Mary. â€Å"I think I do and they think I do,† he said. â€Å"I’ve lived on th’ moor with ’em so long. I’ve watched ’em break shell an’ come out an’ fledge an’ learn to fly ‘an begin to sing, till I think I’m one of ’em.† (Page 95) 2 His mind is unfettered and unspoilt by a formal education, especially one that almost encourages passive learning i.e., the vessels to be filled approach, over active exploration and discovery. Mary and later Colin learn to become independent and active thinkers. â€Å"Colin saw it all, watching each change as it took place. Every morning he was brought out and every hour of each day when it didn’t rain he spent in the garden. He would lie on the grass â€Å"watching things growing,† he said. â€Å"If you watched long enough you could see the buds unsheathe themselves.† (Page221) 2 This positive attitude to learning and education can also be seen in Goodnight Mr Tom. Will has a formal education, but has to grow in spirit to progress in the mind. Again it’s the positiveness of the people and surroundings that help him to a new confidence. â€Å"We’ll begin this evening,† he said sharply. â€Å"That do?† â€Å"Wot?† â€Å"Learnin’ to read and write. I’ll teach you to write yer own name for a beginnin’.† (Page 102) 3 His times of growth and change correspond to when he is with nature. He makes friends and begins to learn how to interact whilst picking blackberries. He becomes more relaxed and confident whilst on holiday by the sea. Again there is this almost holistic approach as Will improves physically, mentally and emotionally. He is able to express himself through art and then acting as his confidence grows. Finally through nature and physical expenditure he is able to come to terms with the grief and loss in his life. In both texts the children are changed by the country folk around them and the ideals and life that they uphold. These rustic folk become educators and healers through their wisdom and plain good sense. The children bloom through a newfound confidence and most importantly an acceptance of oneself. Once this happens they can then consciously and unconsciously redeem the adults around them. In these ways the Wordsworthian ideals are prevalent throughout the texts. Bibliography ENGLISH ROMANTIC VERSE;PENGUIN BOOKS;1986. FROM BLAKE TO BYRON; BORIS FORD; PENGUIN BOOKS; 1982. THE SECRET GARDEN; FRANCES HODGESON BURNETT; PENGUIN CLASSICS; 1995. GOODNIGHT MR TOM; MICHELLE MAGORIAN; PUFFIN BOOKS; 1981. ROMANTIC CRITICAL ESSAYS; DAVID BROMWICH; CAMBRIDGE UNIVERSITY PRESS; 1987. BEYOND ROMANTICISM; ROUTLEDGE; 1992. LITERATURE, EDUCATION AND ROMANTICISM; ALLAN RICHARDSON; CAMBRIDGE UNIVERSITY PRESS; 1984.

Geographical Discoveries

Great geographical discoveries – a popular term geographical discoveries made at the turn of the fifteenth and sixteenth centuries, in particular: circumnavigation Cape of Good Hope by Diaz (1488), the discovery of America by Columbus (1492), and then the conquest, trip [[Vasco da Gama | to India (1498) and the first trip around the world, Magellan (1519-1522). These events triggered a further voyages of discovery and contributed to a significant widening of the geographical horizon of Europeans. Expedition of Christopher Columbus Rulers of Spain, they realized that they begin to lose the distance to Portugal, which definitely lead the quantity organized expeditions. But so far Spain was busy fighting with the Arabs, who defended her at the last stronghold – Grenada. When in 1492 the Saracens were expelled from the Iberian peninsula, Ferdinand and Isabella agreed to finance the expedition, which presented them with a description of the Genoese Christopher Columbus. The traveler asked the first king of Portugal. Presented a plan aimed at shipping on the west and in accordance with the map of Ptolemy, after crossing the Atlantic to reach Asia. However, not met with favor. With the same plan, asked the king of Spain. Under the agreement, written by Columbus from the royal couple: Columbus was appointed for life admiral, governor and viceroy of the newly discovered lands. 1 / 10 of income from the newly discovered land was to belong to Columbus, the rest of the royal treasury. In return, Columbus promised to cover 1 / 8 the cost of the expedition. The rest covered the royal couple. And the expedition of Christopher Columbus (1492-1493) The expedition set sail on August 3, 1492 from the port of Palos de la Frontera. The first stage of the journey were previously discovered the Canary Islands, then Columbus sailed along the 28 parallel to the west. The crew, consisting of about 90 people after 3 weeks of shipping began to rebel, when it turned out that you can not see land. 29. 09. Columbus in his diary wrote that it was rebellion. 11. 10. Columbus erected ultimatum – if within 24 hours will not see the land has ordered outflow. Fortunately for Kolumba12 October after three months of the expedition, when the entire crew of the ship was already tired and actually threatened Columbus's death, Juan Rodriguez Bermejo saw the crow's nest land. The expedition landed on the island probably Watling (called Guanahani by the Indians), a small island group of the Bahamas. In the natives pointed gold ornaments. Interviewed about their origin indicated the direction to the south. Judging from this that lies to the north of the mainland, Columbus chose a new course to the southwest. Indians called the island's inhabitants. October 28 Columbus arrived in Cuba, then on December 6 found another island of Haiti / Hispaniola and the smaller islands, which he called Isabella and Fernandina in honor of the royal couple. Then there was a crisis – in late January and February turned out that the admiral ship sank and the Santa Maria, Columbus ordered the return to their homeland. In March 1493, two ships returned to Palos. Second expedition of Christopher Columbus (1493 – 1494) September 25, 1493, the expedition set off another. This time the expedition better equipped, numbering more ships (about 15, the number of crew: about 1750). The expedition lasted 1. 5 years. This time, Columbus chose a more southern route, and thus reached land in the area of the Lesser Antilles. Subsequently discovered the island of Dominica, Marie – Galante, Guadeloupe, Antigua and Puerto Rico. Nov. 22 Columbus arrived in Haiti again, to see that the people left there, no one survived. How domyslono, all perished in the struggle with the natives. In the longer journey Columbus sailed along the southern coast of Cuba and discovered Jamaica. However, the absolute gggaaaTymczasem proceeding to Columbus alienated a large part of his crew. Discouraged many hardships and lack of legendary riches separated themselves from the trip and started searching on your own. Others returned to Spain, choking many complaints on Columbus. Influenced by the enemies of Columbus postulated to take privileges granted to him earlier, and in his place appointed royal governor of the newly discovered lands. In this situation, Columbus on March 19 headed back to Spain, where he arrived June 11. At the court managed to clear himself of the charges against him, obtained a confirmation of earlier privileges and the promise of organizing the next, the third expedition. Third expedition of Christopher Columbus (1498 – 1500) Another, already the third expedition took place in 1498 on her organization had to wait so much, because it failed to fully restore confidence in what it darzono. In fact, only during this expedition, Christopher Columbus saw the mainland. It was South America, but that's when fate turned away from Columbus. Columbus autocratic favor of his people, in particular his son – Diego. She came to the undoubted frustration at the lack of major economic successes and difficulties expeditions in relations with the natives. Just as during the second expedition, news arrived of the problems to the crown. Meanwhile, it was decided to act more decisively. In June 1500 sent to the west of Francis Bobadilla, which were endowed with wide powers of attorney. After reviewing the situation in Haiti, he ordered arrest of Columbus and his son, and shackled to send them to Spain. At the Columbus site again managed to clear themselves of charges and return to the graces of the royal pair. The result was a fourth and last expedition of Columbus to America. IV expedition of Christopher Columbus (1502 -1504) May 9, 1502 flotilla of four ships and 150 crew company Columbus went west again. This time the situation was urgent. In the meantime, Vasco da Gama discovered the route to India around the African continent. Columbus urgently needed was a success proving that the road to the west is shorter, more comfortable and safer. Columbus's intention was to find the transition to water, which eventually took him to lead India. He expected to go to the west of Cuba. There was headed in his expedition. Flowing in this direction reached the coasts of Honduras and the Mosquito Coast on the east coast of Nicaragua. There, the natives learned about the â€Å"rich kingdoms† (Mayan civilization, and perhaps even the Inca Empire) and the â€Å"great sea† (Pacific Ocean), which lies further west, but despite strenuous attempts failed to find a water passage to the reservoir. Having lost two of the four ships, resigned to return to Cuba, then to Jamaica. There he was forced to settle the remaining ships aground. Materials originating in the damaged ships were used for the construction of fortified settlements. One of the companions of Columbus, Diego Mendez, the Indian boats set off for help survivors. But it was only after months wandering managed to get to Haiti, where he brought help. In the meantime Columbus was seriously ill and in such condition were transported him to Spain, where he arrived November 25, 1504. Summary of accomplishments of Christopher Columbus Given what Columbus has to say that the end of his life was tragic. After returning from the expedition moved to fourth place Vailadolid seriously ill, and having almost the status of a beggar. He died on May 20, 1506 was actually not knowing that he discovered America. He was convinced that came to Japan, to China, to India, and the mainland, which he saw during the third expedition he considered the biblical paradise. Meanwhile, the Portuguese and Spaniards, and realized that Columbus did not reach India, and discovered a new land. Another version of the last years of his life of Columbus presents a mysterious manuscript of Puri, according to which Columbus had died many years later and still take one-fifth trip to the West Indies. The authenticity of this source is given, however, questioned by most scholars Ferdinand Magellan (port. Fernao de Magalhaes, Spanish. Fernando de Magallanes, born. In the spring of 1480, as amended. April 27, 1521) – Portuguese sailor in the service of the Spanish maritime explorer and adventurer. He called the Pacific Ocean (Pacific). September 20, 1519 set out from Portugal by the western, or by the Atlantic Ocean to the Spice Islands in the Malay Archipelago. The expedition, which sailed under his command as the first circumnavigated the Earth. He died on April 27 killed by the inhabitants of the island of Mactan in the Philippine Archipelago Christopher Columbus (born 25 August or 31 October 1451 in Genoa (Italy) – died. May 20, 1506 in Valladolid, cat Cristofor Colom, owned by Cristoforo Colombo, Spanish. Cristobal Colon) – European sailor and navigator (probably Catalan by recent discoveries), captain of the expedition, which flowed on the three ships Santa Maria, Nina and Pinta under the flag of Castile in search of the western sea route to India, as the first in the history of geographical discoveries of modern beat tropical Atlantic Ocean and 12 October 1492 reached the West Indies (Antilles ) off the coast of America – the continent at that time unknown in Europe. Was appointed as admiral and made the first governor of the Spanish colonies in Central America, the organizer and master of four transatlantic discovery expeditions from Spain to America. Diaz used the discovery of Vasco da Gama. In 1497 another expedition was launched. Da Gama sailed around the Cape of Good Hope and headed towards Asia. Docked in the port of Calicut in India. Returned to the country in 1499 along with a large cargo of gold and spices. The country welcomed him enthusiastically. Maritime route to India became a reality. No wonder that the success of this expedition had a big impact naorganizowanie next. Henry the Navigator Portugal at least because of its location lent itself perfectly to the base for ocean expeditions. Despite the advantages of geographical location odegralaby probably not such a role in the great geographical discoveries, if not enthusiasm and dedication to Prince Henry (1394-1460) Henry called Sailor. After the conquest by the Portuguese in 1415 On the Moroccan coast Ceutry Henry was convinced that further expansion in Africa will bring great benefits. Counting on profits from trading gold, slaves, ivory, and pepper. With his support along the western coast of Cape Sangres organized a sort of database connection with the research center, where he collected all the geographical and navigational data and worked on the construction of sailing ships. For seventy years the Portuguese sailing ships were moving farther and farther south along the African coast, reaching successive headlands: Nun, Bojador, Blanco and 1445 Green Cape. During these expeditions the Portuguese discovered and colonized offshore islands and archipelagos – Madeira, the Canary Islands, Cape Verde. They assumed a fortified factories on the coast. And as it turned out that gold is less in Africa than they hoped, they took a more profitable procedere, the slave trade. EXPEDITIONS: WYPRARY PORTUGUESE: -Henry the Navigator – Azores, Canary Islands, Cape Verde, crossed the equator in 1471r. , -Bartholomew Diaz – 1488r . – Busz Cape (Cape of Good Hope), Vasco da Gamma– the road to India along the coast of Africa (1497-1498), SPANISH EXPEDITION: Christopher Columbus – the discovery of America (12. 10. 1942r), Hispaniola (Haiti), Cuba and others (1492), Lesser Antilles, the Coast of Central America and South America (1493-1503); -Amerigo Vespucci – realized that America is a new continent (from his name, name); -Ferdinand Magellan – (1519-1522) circumnavigation of the Earth (Magellan Strait, Pacific Ocean, Philippines, Borneo) – died in 1521r. In the Philippines, an expedition Sebastian del Cano finished; – Francis Drake (English) – and the circumnavigation of South America (the world); CIVILIZATIONS AND SOUTH CENTRAL AMERICA: Maya: V w. n. e. – The beginnings of civilization in the areas of Central America (Yucatan plw. ) with its capital in Majapan; Economy: -Wypaleniskowa (incandescent), -Grown: beans, wheat, -Craft, art, the pyramid; -Religion based on the sun-god cults, rites – human sacrifice; -Totalitarian power, absolute, hereditary; -The principal adviser to the ruler – the high priest; -Did not know the wheel or arc; -Calendar (365 days divided into 18 months); -Developed astronomy; -Know the time (to understand this concept) decimal system; Were aware of the layout of digits; The Aztecs: The thirteenth century – the beginnings of civilization in the areas of Mexico today, with its capital in Tenochtitlan; -Developed economy; -Grown: tomatoes, cotton, cocoa; -Money: cocoa beans or golden sand; -Tools more advanced than the Mayans; -Construction: the temples; -Ruler chosen from among the administrative units; -Bloody rituals, wor ship of the sun: 1489 – 250 thousand were killed. people as victims of ritual, such as skinned, pulling beating hearts; -Took over the Mayan calendar; Incas: Fifteenth century origins of civilization in the areas of Peru; -Cult of the sun and moon; -A highly developed economy, -Machu Picchu, -Crafts (ornaments of gold); -Totalitarian state, absolute power; -The interests of the subordinated interests of the state; -Residents could not travel to other parts of the country; Courier-Mail (16 thousand. Km of roads) Knotted-letter; -Developed surgery and herbal medicine, hypnosis; 1519r. – Hispanic – Cortez Aztec civilization znieszczenie; XVI – the destruction of the Incas – Izarro;