Bob Misner, age 13, of Tacoma, Wash., for his question:
WHEN WAS THE FIRST STOVE USED?
Earthenwear stoves were used for heating as early as the 700s in China. But it wasn't until about the early 1400s that the Europeans started to use such stoves.
In the American Colonies the first stoves were made in Lynn, Mass., in 1642. They were little more than cast iron boxes with lids.
The American statesman and inventor Benjamin Franklin developed the Franklin stove in the early 1740s. This stove became very popular. It was cast iron and it was fitted into a fireplace. It extended into the room so that three sides gave off heat.
The first practical cooking stove didn't come along until it was designed in the 1790s by a British statesman and inventor named Benjamin Thompson. He became the Count Rumford. His stove, a boxlike brick structure, had holes in the top to hold pots.
Until the early 1800s, almost all of the people in Canada and the United States used fireplaces for both cooking and heating. During the 1830s, advances in ironmaking and transportation made cast iron available. As a result, lots of people purchased iron cookstoves and heating stoves.
Most of the early stoves burned wood. But in 1833, an American inventor named Jordan Mott came up with the first practical coal stove. It was called a baseburner. This stove had ventilation so it could burn coal efficiently.
In 1855, 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 stated to use gas ranges after 1910 when gas became available in pressurized containers.
Electric ranges were first sold in 1909. Early electric stoves cooked extremely slowly, and very few people bought them. It wasn't until the modern cooking unit was developed in 1930 that electric ranges became popular.
Microwave ovens didn't come along until the mid 1950s.
Cooking stoves are called ranges. A range has a cook top with several heating areas and one or two ovens.
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.
Controls regulate the watts of electricity supplied to the coils. The greater the wattage, the hotter the coil becomes.
On a gas range, burners mix air with natural gas or LP gas. LP gas is liquefied petroleum gas. The resulting mixture flows through small holes in the burner. The flowing gas is ignited into a flame by a spark produced by a built in electric device or by a pilot light near the burner.
The heat produced by a gas burner depends mainly on the rate of which the flowing gas reaches the flame. A valve regulates the gas flow.
Hand operated valves control most cooktop burners. Thermostats operate the valves of most oven burners and of some cooktop burners.