Refrigerator

Refrigerator - a device that supports a low temperature in a thermally insulated chamber. Usually used for storing food or items that should be kept in a cool place. Household refrigerator has almost every family in the developed countries. The work is based on the use of the refrigerator cooling unit, which transfers heat from the refrigerator out of the working chamber, where it is dissipated into the environment. There are also commercial refrigerators with a larger cooling capacity, which are used in catering and in shops and industrial refrigerators, the volume of the chamber which can be tens or hundreds of cubic meters, they are used, for example, meat processing plants, factories. Refrigerators can be divided into two types: medium-temperature chamber for food storage and low temperature freezers. Freezer - a separate unit or part of the refrigerator, intended for freezing and storing food. The temperature in the freezer is usually -18 ° C. Recently, the most widely used refrigerator, incorporating both components. The first two-compartment refrigerators were produced by History of the Storage space for products that fill with ice, there were several thousand years ago. For Nero servants harvested on frozen ponds in the mountains of snow and ice. Southern Europe for a long time did not even know that snow and ice can be useful in the economy. The famous traveler and merchant Marco Polo after a long stay in China, wrote a book in which he described all the advantages of ice and snow. From the XVIII century container of pottery and porcelain bottles filled with wine, and then stacked on top of crushed ice. Kind of

Phone

Phone (ancient Greek. Τῆλε «far" and φωνή «voice", "sound") - a device to send and receive sound in the distance. Modern phones carried by the transmission of electrical signals.
Nonelectric "telephone"
Overall, the phone - is any device capable of transmitting sound over long distances. Most first telephones were mechanical devices that are based on sound propagation in continuous media (air) or other physical means, as opposed to electric devices using electromagnetic signals.
According to a letter to «Peking Gazette», in 968, a Chinese inventor Kung-Fu-wing created thumtsein, which is likely to transmit sound through the pipes. Talking through pipes used today in the transmission of sound over short distances between fixed points (on ships, companies, etc.).
"Rope phone" is also known for centuries. There are two diaphragms connected with string or wire.
Electric phone
Millennium after millennium people communicate only by using sound propagation in a continuous medium - air. To send messages over long distances use primitive methods, such as whistles, gongs or drums. An invention is a device that transmit and receive audio would use the properties of electricity, preceded the