TRADUCCIÓN INGLÉS-ESPAÑOL
Jóvenes:
Por favor imprímanlo y llévenlo al día martes a la clase. Thanks a lot
Steam Engines
A steam
engine is a device by means of which heat is transformed into work. Work may be
defined as the result produced by a force acting through space, and is commonly
measured in foot-pounds; a foot-pound represents the work done in raising 1
pound 1 foot in height. The rate of doing work is called power. It has been
found by experiment that there is a definite relation between heat and work, in
the ratio of 1 thermal unit to 778 foot-pounds of work. The number 778 is
commonly called the heat equivalent of work or the mechanical equivalent of
heat.
Heat may be transformed into mechanical work through the medium of steam, by confining a given amount in a closed chamber, and then allowing it to expand by means of a movable wall (piston) fitted into one side of the chamber. Heat is given up in the process of expansion, as shown by the lowered pressure and temperature of the steam, and work has been done in moving the wall (piston) of the closed chamber against a resisting force or pressure. When the expansion of steam takes place without the loss of heat by radiation or conduction, the relation between the pressure and volume is practically constant; that is, if a given quantity of steam expands to twice its volume in a closed chamber of the kind above described, its final pressure will be one-half that of the initial pressure before expansion took place. A pound of steam at an absolute pressure of 20 pounds per square inch has a volume of practically 20 cubic feet, and a temperature of 228 degrees. If now it be expanded so that its volume is doubled(40 cubic feet), the pressure will drop to approximately 10 pounds per square inch and the temperature will be only about 190 degrees. The drop in temperature is due to the loss of heat which has been transformed into work in the process of expansion and in moving the wall (piston) of the chamber against a resisting force, as already noted.
Principle of the Steam Engine
The steam engine makes use of a closed chamber with a movable wall in transforming the heat of steam into mechanical work in the manner just described. Fig.1 shows a longitudinal section through an engine of simple design, and illustrates the principal parts and their relation to one another.
Heat may be transformed into mechanical work through the medium of steam, by confining a given amount in a closed chamber, and then allowing it to expand by means of a movable wall (piston) fitted into one side of the chamber. Heat is given up in the process of expansion, as shown by the lowered pressure and temperature of the steam, and work has been done in moving the wall (piston) of the closed chamber against a resisting force or pressure. When the expansion of steam takes place without the loss of heat by radiation or conduction, the relation between the pressure and volume is practically constant; that is, if a given quantity of steam expands to twice its volume in a closed chamber of the kind above described, its final pressure will be one-half that of the initial pressure before expansion took place. A pound of steam at an absolute pressure of 20 pounds per square inch has a volume of practically 20 cubic feet, and a temperature of 228 degrees. If now it be expanded so that its volume is doubled(40 cubic feet), the pressure will drop to approximately 10 pounds per square inch and the temperature will be only about 190 degrees. The drop in temperature is due to the loss of heat which has been transformed into work in the process of expansion and in moving the wall (piston) of the chamber against a resisting force, as already noted.
Principle of the Steam Engine
The steam engine makes use of a closed chamber with a movable wall in transforming the heat of steam into mechanical work in the manner just described. Fig.1 shows a longitudinal section through an engine of simple design, and illustrates the principal parts and their relation to one another.
Tradition of Teatime
While most associate tea time with England, the practice of tea drinking actually began in France nearly twenty-two years before tea was even introduced in England. King Charles II, who ruled England in the seventeenth century, brought with him a Portuguese bride and a firm tea drinking tradition. As the king and queen were tea drinkers, a novelty in England at the time, the tradition immediately became popular among the wealthy.Tea replaced ale as the official beverage in England in very short order. When Queen Anne, a successor to King Charles II, chose tea over ale for her morning drink, she set a new standard in all of England. Also during the eighteenth century, tea became the customary drink with an evening meal to satisfy the hunger and thirst of those working during the Industrial Revolution.
High Tea
High tea was introduced to England in the eighteenth century. Traditionally only two meals were eaten in most households - breakfast and dinner. Dinner was served late in the evening. However, when workers came home from the more industrialized labors, they were more than ready for a full serving of breads, meat, cheeses and such. These were served on a high table along with tea much like a dinner. Thus, the late afternoon meal was called high tea. Today, high tea is mistakenly identified as a formal tea in the afternoon along with pastries, but those delicacies would never have been found in a true high tea - they wouldn't be hearty enough.Teatime
Anna Maria Stanhope, the Duchess of Bedford, is credited with having begun afternoon teatime. Once a lady-in-waiting to Queen Victoria, Anne began to suffer a "sinking feeling" in her stomach around four o'clock in the afternoon as the noon meal had become skimpier. To help her make it from the noon meal to the late formal dinner, Anne first asked servants to sneak in a pot of tea and bread.Later, as she became more comfortable with her late afternoon meal, Anne began asking friends to join her in her rooms at Belvoir Castle around five o'clock in the afternoon. She followed the traditional European tea service format and served a collection of small cakes, bread and butter sandwiches, sweets and tea.
When she returned to London, the Duchess had enjoyed her summer treat so much that she continued the practice by inviting friends to visit for "tea and a walk in the fields." Other noblewoman soon took up the practice of serving a light afternoon meal and the true teatime was born.
