Janice Pitmans age 12, of Williamsport, penna., for her question:
Why are there Centigrade and Fahrenheit thermometers?
Two hundred and fifty years ago a patient might say he had a raging fever. His doctor had no way to prove him wrong. People could argue about which was the hottest day of the year ‑ but no one could prove it. Heat and cold were matters of opinion. For Gabriel Fahrenheit had not yet invented his scale of temperatures. This is the ladder of degrees that runs up the side of the thermometer. The thread of mercury or alcohol in the thermometer rises and falls along this scale of degrees. It tells us exactly how warm or how cool things are.
Galileo made a thermometer in 1593. It was clumsy and did not show different degrees of temperature. Fahrenheit made a better thermometer and worked out a graded scale of temperatures in 1724. A scale must have a top and a bottom. Fahrenheit took for the bottom of his thermometer the temperature of the coldest thing known, a mixture of ice, sea salt and water.
Fahrenheit's thermometer was a glass bulb of mercury fixed to a glass tube ‑ the grandpappy of our slick, modern temperature‑takers. The mercury expanded when warm and rose in the tube. It shrank when cool and fell in the tube. Fahrenheit put this thermometer into the chilly mixture and waited for the mercury to stop falling in the tube. Here he put mark zero For the top of the scale he took his own temperature. He divided the space between into 12s and later into 96, degrees. Plow he had a scale to prove the temperature of anything between ice water and the human body. With a better thermometer the human body was found to be closer to 98 degrees.
This was how our Fahrenheit scale was invented. In America, Canada and England it is used on the clinical thermometer and by weathermen. It wasp of course, named for the inventor. On the Fahrenheit scale water boils at 212 degrees. There are 180 Fahrenheit degrees between the freezing and the boiling point of water.
Scientists wanted a more simple scale, based on the decimal system. In 1742 the French scientist Celsius made a scale with 100 degrees between the freezing and the boiling point of water. We call it the centigrade scale. It is used by scientists and the people of continental Europe adopted it for all purposes.
Sometimes we have the bother of translating Fahrenheit and centigrade degrees. The same amount of heat is needed to heat water from freezing to the boiling point. On the Fahrenheit scale this is divided into 180 degrees. on the centigrade scale into 100 degrees. Hence 180 Fahrenheit degrees are equal to 100 centigrade degrees.
It follows that a Fahrenheit degree equals 5/9 centigrade degrees and on centigrade degree equals 9/5 Fahrenheit degrees. We must take into account the fact that the Fahrenheit scale begins with 32, the centigrade with zero In translating the centigrade figure equals 5/9 of the. Fahrenheit number minus 32. The Fahrenheit figure equals 9/5 of the centigrade figure plus 32. When you're real good at the puzzle game of mathematics you can turn this trick in a jiffy.