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The Straight Dope

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Everybody knows 0 degrees on the Celsius scale is the freezing point of water and 100 degrees is the boiling point. On the Fahrenheit scale, however, freezing is 32 degrees and boiling 212. How on earth were these numbers arrived at? Do 0 and 100 degrees Fahrenheit mean anything? --Leslie, Montreal, Quebec

Researchers have gone to their graves trying to figure out what old man Fahrenheit was up to, Leslie. Here's the story as well as I can piece it together:

Daniel Gabriel Fahrenheit (1686-1736) was a German instrument maker who invented the first practical mercury thermometer. Casting about for a suitable scale for his device, he visited the Danish astronomer Ole Romer, who had devised a system of his own. As it turned out, it was a case of the blind leading the blind.

Romer had decided that the boiling point of water should be 60 degrees, which at least had the strength of numerological tradition behind it (60 minutes in an hour, right?). But zero was totally arbitrary, the main consideration apparently being that it should be colder than it ever got in Denmark. (Romer didn't like using negative numbers in his weather logbook.) In addition to the boiling point of water, the landmarks on Romer's scale were the freezing point of water, 7 1/2 degrees, and body temperature, 22 1/2 degrees.

D.G., simple soul that he was, thought this cockeyed system was the soul of elegance. He made one useful change: to get rid of the fractions, he multiplied Romer's degrees by 4, giving him 30 for the freezing point and 90 for body temperature. Then, for reasons nobody has ever been able to fathom, he multiplied all the numbers by 16/15, making 32 freezing and 96 body temperature. Boiling point for the time being he ignored altogether.

By and by Fahrenheit got ready to present his scale to London's Royal Society, the scientific big leagues of the day. It dawned on him that it was going to look a little strange having the zero on his scale just sort of hanging off the end, so to speak. So he cooked up the explanation that zero was the temperature of a mix of ice, water, and ammonium chloride.

At some point Fahrenheit figured out that the boiling point of water came in at 212 degrees. Over time this replaced body temp as the upper landmark on his scale. Meanwhile, as more precise measurements were made, body temperature had to be adjusted to 98.6 degrees.

In short, 100 means nothing at all on the Fahrenheit scale, 96 used to mean something but doesn't anymore, and 0 is colder than it ever gets in Denmark. Brilliant. Lest we get too down on Fahrenheit, though, consider Anders Celsius, who devised the centigrade scale (0 to 100). Everybody agrees Celsius's scale makes more sense than Fahrenheit's. Trouble is, the original Celsius scale had 100 for freezing, 0 for boiling. In other words, it was upside-down. (The numbers were reversed after Celsius's death.) You look back at these guys, sometimes you don't know whether to laugh or cry.

Adolf Hitler spoke of the empire he was trying to build as the Third Reich. What were reichs One and Two? --Wilberforce, Blue Mounds, Wisconsin

According to a soon-to-be-published tome called The Hitler Fact Book by Thomas Fuchs (like I say, I get the most amazing stuff in the mail), "the first Reich was the Holy Roman Empire of the Middle Ages; the second, the one established by Bismarck and ended by Germany's defeat in 1918." The term was a favorite of Hitler's propaganda minister, Joseph Goebbels. Hitler himself wasn't that crazy about it, Fuchs notes; he outlawed the term at the beginning of World War II and referred to his realm merely as the Reich. Another Nazi term, "Thousand Year Reich," supposedly had its origin in a remark by Hitler following the purge of June 1934, when he had many of his onetime supporters murdered. Hitler said the victims had been plotting a revolt, and promised there would be no more such strife for a thousand years.

Art accompanying story in printed newspaper (not available in this archive): illustration/Slug Signorino.