History of the Oven From Cast Iron to Electric

History of the Oven From Cast Iron to Electric Ancient people first began cooking on open fires. The cooking fires were placed on the ground and later simple masonry construction was used to hold the wood and/or food. Simple ovens were used by the ancient Greeks for making bread and other baked goods. By the middle ages, taller brick mortar hearths, often with chimneys were being built. The food to be cooked was often placed in metal cauldrons that were hung above the fire. The first written historical record of an oven being built refers to an oven built in 1490 in Alsace, France. This oven was made entirely of brick and tile, including the flue. Improvements to Wood Burning Ovens Inventors began making improvements to wood burning stoves primarily to contain the bothersome smoke that was being produced. Fire chambers were invented that contained the wood fire, and holes were built into the top of these chambers so that cooking pots with flat bottoms could be placed directly upon replacing the cauldron. One masonry design of note was the 1735 Castrol stove (aka stew stove). This was invented by French architect Franà §ois Cuvillià ©s. It was able to completely contain the fire and had several openings covered by iron plates with holes. Iron Stoves Around 1728, cast iron ovens really began to be made in high quantities. These first ovens of German design were called Five-plate or Jamb stoves. Around 1800, Count Rumford (aka Benjamin Thompson) invented a working iron kitchen stove called the Rumford stove that was designed for very large working kitchens. The Rumford had one fire source that could heat several cooking pots.  The heating level for each pot could also be regulated individually. However, the Rumford stove was too large for the average kitchen and inventors had to continue to improve their designs. One successful and compact cast iron design was Stewarts Oberlin iron stove, patented in 1834. Cast iron stoves continued to evolve, with iron gratings added to the cooking holes, and added chimneys and connecting flue pipes. Coal and Kerosene Frans Wilhelm Lindqvist designed the first sootless kerosene oven. Jordan Mott invented the first practical coal oven in 1833. Motts oven was called the baseburner. The oven had ventilation to burn the coal efficiently. The coal oven was cylindrical and was made of heavy cast iron with a hole in the top, which was then enclosed by an iron ring. Gas British inventor  James Sharp patented a gas oven in 1826, the first semi-successful gas oven to appear on the market. Gas ovens were found in most households by the 1920s with top burners and interior ovens. The evolution of gas stoves was delayed until gas lines that could furnish gas to households became common. During the 1910s, gas stoves appeared with enamel coatings that made the stoves easier to clean. One important gas design of note was the AGA cooker invented in 1922 by Swedish Nobel prize winner Gustaf Dalà ©n. Electricity It was not until the late 1920s and early 1930s that electric ovens began to compete with gas ovens.  Electric ovens were available as early as the 1890s. However, at that time, the technology and distribution of the electricity needed to power these early electric appliances still needed improvements. Some historians credit  Canadian Thomas Ahearn with inventing the first electric oven in 1882. Thomas Ahearn and his business partner Warren Y. Soper owned the Chaudiere Electric Light and Power Company of Ottawa. However, the Ahearn oven was only put into service in 1892, in the Windsor Hotel in Ottawa. The Carpenter Electric Heating Manufacturing Company invented an electric oven in 1891. An electric stove was exhibited at the Chicago Worlds Fair in 1893. On June 30, 1896, William Hadaway was issued the first patent for an electric oven. In 1910, William Hadaway went on to design the first toaster made by Westinghouse, a horizontal combination toaster-cooker. One major improvement in electric ovens was the invention of resistor heating coils, a familiar design in ovens also seen in hotplates. Microwaves The microwave oven was a by-product of another technology. It was during a radar-related research project around 1946 that Dr. Percy Spencer, an engineer with the Raytheon Corporation, noticed something very unusual when he was standing in front of an active combat radar. The candy bar in his pocket melted. He began to investigate and soon enough, the microwave oven was invented.

Expansionary Monetary Policy and Aggregate Demand

Expansionary Monetary Policy and Aggregate Demand To understand the impact of expansionary monetary policy on aggregate demand, lets take a look at a simple example. Aggregate Demand and Two Different Countries The example starts as follows: In Country A, all wage contracts are indexed to inflation. That is, each month wages are adjusted to reflect increases in the cost of living as reflected in changes in the price level. In Country B, there are no cost-of-living adjustments to wages, but the workforce is completely unionized (unions negotiate 3-year contracts). Adding Monetary Policy to our Aggregate Demand Problem In which country is an expansionary monetary policy likely to have a larger effect on aggregate output? Explain your answer using aggregate supply and aggregate demand curves. The Effect of the Expansionary Monetary Policy on Aggregate Demand When interest rates are cut (which is our expansionary monetary policy), aggregate demand (AD) shifts up due to the rise in investment and consumption. The shift up of AD causes us to move along the aggregate supply (AS) curve, causing a rise in both real GDP and the price level. We need to determine the effects of this rise in AD, the price level, and real GDP (output) in each of our two countries. What Happens to Aggregate Supply in Country A? Recall that in Country A all wage contracts are indexed to inflation. That is, each month wages are adjusted to reflect increases in the cost of living as reflected in changes in the price level. We know that the rise in Aggregate Demand rose the price level. Thus due to the wage indexing, wages must rise as well. A rise in wages will shift the aggregate supply curve upwards, moving along the aggregate demand curve. This will cause prices to increase further, but real GDP (output) to fall. What Happens to Aggregate Supply in Country B? Recall that in Country B there are no cost-of-living adjustments to wages, but the workforce is completely unionized.Unions negotiate 3-year contracts. Assuming the contract is not up soon, then wages will not adjust when the price level rises from the rise in aggregate demand. Thus we will not have a shift in the aggregate supply curve and prices and real GDP (output) will not be affected. The Conclusion In Country B we will see a larger rise in real output, because the rise in wages in country A will cause an upward shift in aggregate supply, causing the country to lose some of the gains it made from the expansionary monetary policy. There is no such loss in Country B.