Rebecca May, age 13, of Nashua, N.H., for her question:
WHEN DID WE COME UP WITH THE STOVE?
For centuries man used the fireplace for heating and cooking. But the Chinese did come up with an earthenware stove for heating as early as the 700s. Such stoves didn't appear in Europe until the 1400s.
The first stoves produced in the American Colonies came along in 1642. They were made in the Massachusetts city of Lynn and were little more than cast iron boxes with lids.
Benjamin Franklin, the American statesman and inventor, developed the Franklin stove in the early 1740s. This stove, a cast iron enclosure, fitted into a fireplace. It extended into the room so that three sides gave off heat.
The first practical cooking stove was designed in the 1790s by a British statesman and inventor named Count Rumford. This stove, a boxlike brick structure, had holes in the top to hold pots and pans.
Even though there were stoves available in the 1700s, most of the people in Canada and the United States used their fireplaces for cooking and heating until the early 1800s. During the 1830s, advances in ironmaking and transportation made cast iron widely available. As a result, iron cookstoves and heating stoves became popular.
Most of the early stoves burned wood. The first practical coal stove, called a baseburner, was patented in 1833 by an American inventor named Jordon Mott. This type of stove had ventilation so it could burn coal efficiently.
A German chemist named Robert Bunsen invented the first practical gas burner. In the 1860s, ranges based on Bunsen's burner became popular in cities that had gas piped into homes for use in gaslights. People who lived in rural areas began to use gas ranges after 1910, when gas became available in pressurized containers.
Electric ranges were first sold in 1909, but they weren't efficient and not popular.
After the modern cooking unit was developed in 1930, the electric range became very popular. And in the mid 1950s, the microwave ovens were introduced and quickly accepted.
Modern electric ranges have heating units in which an electric current generates heat.. Most electric ranges have four circular heating units on the cooktop and one or two rectangular units in each oven.
The amount of heat produced by a heating unit of an electric range can be regulated easily. Some units have controls that regulate the watts of electricity supplied to the coil. The greater the wattage, the hotter the coil becomes. Another kind of unit control turns the current on and off at intervals that vary with the heat desired.
Gas ranges have burners which mix air with natural gas or liquefied petroleum gas. The resulting mixture flows through small holes in the burner. The flowing gas is ignited into a flame. The heat produced by a burner depends mainly on the rate at which the flowing gas reaches the flame.
Microwave ovens cook food by using short radio waves that penetrate the food and make its molecules vibrate. Friction among the moving molecules produces heat, which cooks the food. '