Fahrenheit - Cecil missed something

[GreenWyvern]

Please note that

212 - 32 = 180

The number of degrees from freezing point to boiling point on the fahrenheit scale is exactly 180 degrees, a fairly reasonable round number.

This shows that Fahrenheit did in fact take the boiling point into account, and that his scale is not as weird as all that.

[RedSwinglineOne]

Link On the Fahrenheit scale, do 0 and 100 have any special significance?

[Blaster Master]

In the linked article, it says that Fahrenheit multiplied the numbers by 4 to give him 30 and 90, then multiplied it by 16/15 to get 32 and 96 for some unknown reason. Is it possible that that reason was to make the boiling point of water, along with those other two values all whole numbers? If he hadn't multiplied by that, boiling point would be 198.75.

As for 180 degrees being the difference, being that he had intended to base the system on freezing point and human body tempurature, the fact that it happens to be a multiple of 10 (which is what I assume you mean by "reasonable") isn't necessarily evidence that it was taken into account. Similarly, the "fact" that his zero point coincides with ice water and ammonium chloride, doesn't necessarily mean he actually took that into account either.

[GreenWyvern]

Originally Posted by Blaster Master

As for 180 degrees being the difference, being that he had intended to base the system on freezing point and human body tempurature, the fact that it happens to be a multiple of 10 (which is what I assume you mean by "reasonable") isn't necessarily evidence that it was taken into account. Similarly, the "fact" that his zero point coincides with ice water and ammonium chloride, doesn't necessarily mean he actually took that into account either.

I thought that the significance of the number 180 was so immediately obvious that it didn't need any further comment. Obviously, I was wrong. Ever use a protractor? Ever hear the expression "180-degree turn" ?

The numbers 60, 180, 360 have been used for divisions of time and space for thousands of years.

You noticed that 180 is divisible by 10. If you wok it out, you'll find that it's actually divisible by 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 36, 45, 90. That's why it's useful, especially if you don't have a calculator.

My point is that the article is wrong.

Fahrenheit based his scale on the freezing point of water and the boiling point of water, nothing else. He set the difference as 180 - an obvious number to anyone familiar with geometry or astonomy. He then made the starting point 32 degrees further down in order to avoid negative numbers, which were still quite esoteric to ordinary people at that time.

[DSYoungEsq]

Originally Posted by GreenWyvern

I thought that the significance of the number 180 was so immediately obvious that it didn't need any further comment. Obviously, I was wrong. Ever use a protractor? Ever hear the expression "180-degree turn" ?

The numbers 60, 180, 360 have been used for divisions of time and space for thousands of years.

You noticed that 180 is divisible by 10. If you wok it out, you'll find that it's actually divisible by 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 36, 45, 90. That's why it's useful, especially if you don't have a calculator.

My point is that the article is wrong.

Fahrenheit based his scale on the freezing point of water and the boiling point of water, nothing else. He set the difference as 180 - an obvious number to anyone familiar with geometry or astonomy. He then made the starting point 32 degrees further down in order to avoid negative numbers, which were still quite esoteric to ordinary people at that time.

All of which would be quite nice, if it wasn't for the fact that we have the actual writings of Daniel Farenheit himself saying you are wrong. Farenheit wrote in 1724 that he created a scale in which body temperature was 96° and mercury boiled at 600°. It wasn't until someone came along later and adjusted the scale to create an easy conversion that the boiling point of water got fixed at 212° (which resulted in mercury's boiling point being actually 674° F).

So Farenheit himself never actually mentioned the difference between the boiling and freezing points of water as relevant to his scaling, and this would be unsurprising given that his original scale didn't establish a neat interval between the two. It was the later editors that helped us out, there.

If you are going to call Uncle Cecil "wrong," you probably ought to have, like, you know, evidence to support you.



Citation: D. G. Fahrenheit.
Experimenta et Observationes de Congelatione aquae in vacuo factae a D. G. Fahrenheit, R. S. S..
Philosophical Transactions (London), volume 33, page 78 (1724).

the relevant text of which can be found here.

[GreenWyvern]

Originally Posted by DSYoungEsq

So Farenheit himself never actually mentioned the difference between the boiling and freezing points of water as relevant to his scaling, and this would be unsurprising given that his original scale didn't establish a neat interval between the two. It was the later editors that helped us out, there.

I concede that the scale wasn't originally conceived that way by Fahrenheit himself, and that it was later changed by people with more common sense.

However, the original question said,

"On the Fahrenheit scale, however, freezing is 32 degrees and boiling 212. How on earth were these numbers arrived at?"

This is a question about the scale as it is now, not about how Fahrenheit originally conceived it. I think that I've answered this question, whereas the original reply didn't.

[jjimm]

Originally Posted by GreenWyvern

If you wok it out...

What temperature should the wok be?

[Baldwin]

Originally Posted by GreenWyvern

This is a question about the scale as it is now, not about how Fahrenheit originally conceived it. I think that I've answered this question, whereas the original reply didn't.

No, you haven't, and yes, it did.

[Pushkin]

Hmmm, I don't think I've seen a guest so cocky that they'd use a smilie to compliment themselves on taking on Cecil.

[russl5445]

FWIW, I heard a very reasonable explanation for the choice of 32 & 96 degrees: it makes it easy to build an accurate thermometer because 32 and 64 are both powers of two. This is important because the original thermometers would have been made by hand, not in a factory. So each thermometer would be a little different, and would have to be calibrated by hand.

You take your brand new (unmarked) thermometer and measure human body temperature, and the temperature where water freezes. Make little marks on the thermometer for each. It's easy to then find the midpoint between the two marks - that's 64 degrees. You can then measure out exactly where 0 degrees should be. You then divide the regions in half, over and over. Since 32 and 64 are both powers of two, it's easy and accurate.

At least, that's what I heard long ago.

[RedSwinglineOne]

Originally Posted by GreenWyvern

You noticed that 180 is divisible by 10. If you wok it out, you'll find that it's actually divisible by 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 36, 45, 90. That's why it's useful, especially if you don't have a calculator.

My point is that the article is wrong.

And what good does this do you? Exactly what type of problem requires you to divide the temperature? Half as warm? Twice as cold?

[MikeG]

Originally Posted by russl5445

FWIW, I heard a very reasonable explanation for the choice of 32 & 96 degrees: it makes it easy to build an accurate thermometer because 32 and 64 are both powers of two. This is important because the original thermometers would have been made by hand, not in a factory. So each thermometer would be a little different, and would have to be calibrated by hand.

You take your brand new (unmarked) thermometer and measure human body temperature, and the temperature where water freezes. Make little marks on the thermometer for each. It's easy to then find the midpoint between the two marks - that's 64 degrees. You can then measure out exactly where 0 degrees should be. You then divide the regions in half, over and over. Since 32 and 64 are both powers of two, it's easy and accurate.

At least, that's what I heard long ago.

That's is what I remember my history of science prof saying years ago as well. Makes sense from a manufacturing standpoint.

[DSYoungEsq]

Originally Posted by GreenWyvern

I concede that the scale wasn't originally conceived that way by Fahrenheit himself, and that it was later changed by people with more common sense.

However, the original question said,

"On the Fahrenheit scale, however, freezing is 32 degrees and boiling 212. How on earth were these numbers arrived at?"

This is a question about the scale as it is now, not about how Fahrenheit originally conceived it. I think that I've answered this question, whereas the original reply didn't.

Well, they weren't arrived at by worrying one jot about the number 180. First of all, just because it's a cool number is meaningless. Unlike some things (hours of a day, e.g.), it isn't important to be able to divide a temperature difference up into parts like that. What purpose would it serve? Second of all, we have no evidence that 180 was in their thinking. We DO have evidence that the adjustment was made simply to allow for an "easy" conversion factor, given that 32° F was going to stay as the freezing point of water. In short, they looked at the scale as calibrated by Farenheit, which had no easy conversion factor, and they said, "Hey, you know what? If we set the boiling point at 212°, we can use 9:5 as a conversion factor!" The only part 180 played in this was the fortuitous happenstance of being 9/5ths of 100.

I'm glad you dropped by; we always enjoy new vict..., er, that is, new guests. However, if you decide to stay, you will quickly find that what you did here, which is simply speculate on an answer, based on what seemed to be a good idea to you, simply isn't an acceptable method of proof here. We like to rely on things like evidence (when we aren't relying on our own big egos ).

[foolsguinea]

I'd like to underline something DSYoungEsq only implied: Modern "Faherenheit" has been modified to give simple conversions to Celsius. Fahrenheit purists can weep to realize they're using a partially Celsius-derived system!

Incidentally, you know how we're all told that human body temperature is 98.6 degrees? Poppycock. Human body temperature is no way consistent enough to require a measurement to a 10th of a degree Fahrenheit. In Celsius, one speaks of human body temperature as 37.

37 / 5 * 9 + 32 = 98.6

Some fool translated a reasonable approximation to an average degree Celsius into a pseudo-precise measurement of no real scientific value.

Fahrenheit in general is kind of a joke anyway, no one needs degrees that finely graded.

[DSYoungEsq]

Originally Posted by foolsguinea

I'd like to underline something DSYoungEsq only implied: Modern "Faherenheit" has been modified to give simple conversions to Celsius. Fahrenheit purists can weep to realize they're using a partially Celsius-derived system!

Incidentally, you know how we're all told that human body temperature is 98.6 degrees? Poppycock. Human body temperature is no way consistent enough to require a measurement to a 10th of a degree Fahrenheit. In Celsius, one speaks of human body temperature as 37.

37 / 5 * 9 + 32 = 98.6

Some fool translated a reasonable approximation to an average degree Celsius into a pseudo-precise measurement of no real scientific value.

Fahrenheit in general is kind of a joke anyway, no one needs degrees that finely graded.

First of all, your statements start from an incorrect premise. No one is told that "the human body temperature is 98.6 degrees." People's temperatures vary a lot. What we ARE told is that the average temperature (measured orally) is 98.6°F. this IS an accurate statement, because it is a direct conversion from the 37° C figure that was arrived at as an average temperature for a normal, healthy human. And certainly one could determine an "average" (meaning median or mode, depending) temperature for a given sample of humans to the level of a single digit past the decimal; thermometers are certainly accurate to that extent in measuring human body temperature either orally or rectally (or any other way).

As for whether or not it is a "joke", frankly, I am quite happy with the difference between the two scales. I can tell in my own house when the temperature has risen or fallen a single degree Farenheit, which means that it's obviously of some use to know the difference between 71 and 72 degrees.

[John W. Kennedy]

Originally Posted by DSYoungEsq

No one is told that "the human body temperature is 98.6 degrees."

To quote Willmore the Rover, "Why, where hast thou lived? / Amongst the gods?"

[dennisjmillerdds@gmail.com]

Regardless of the historical evidence, I have always believed that 0 and 100 degrees on the Fahrenheit scale were markers for the human body's tolerance of temperature extremes. Simply, 0 F. feels bitterly cold, and 100 F. feels horribly hot.

Could Fahrenheit have felt compelled to place a scientific justification on his scale while really creating something accessible to the general public?

[Fear Itself]

Originally Posted by dennisjmillerdds@gmail.com

Regardless of the historical evidence, I have always believed that 0 and 100 degrees on the Fahrenheit scale were markers for the human body's tolerance of temperature extremes. Simply, 0 F. feels bitterly cold, and 100 F. feels horribly hot.

This is so subjective as to be completely useless. If you are raised in the tropics, 100° isn't so horribly hot, and anything below 40° is going to be bitterly cold. It all depends on your frame of reference.

[DSYoungEsq]

Ah, yes, another warm, welcoming hand of friendship offered to a new poster here.

dennisjmillerdds@gmail.com, the problem with your supposition is that, while 0° F certainly is cold, it's not by any means the coldest temperatures that would be recorded in northeastern Europe, where Farenheit was from (Gdansk, actually), nor is 100° F any more or less "hot" than 101, or 99. Further, they aren't measured very precisely. Finally, there was no reason to make it a scale of 100, given that the possible temperatures go above 100 (and, for that matter, below 0).

Further, Farenheit wasn't working in a vacuum. Rømer's scale had come out in 1701, and that was the first scale established using a brine solution for 0° Rø, where 7.5° Rø was the freezing point of water. Farenheit was apparently simply improving on this scale, attempting to remove some of the potential for negative numbers that the Rømer scale had when measuring temperatures of things you would want to measure the temperature of.

So, really, we must assume that the story he gave us is at least close to what he was attempting at the time, and the fact that we attach meaning to 0 and 100 is more to do with our view of these numbers as interesting than it is to do with anything intended by Herr Farenheit.

[foolsguinea]

Originally Posted by DSYoungEsq

First of all, your statements start from an incorrect premise. No one is told that "the human body temperature is 98.6 degrees." People's temperatures vary a lot. What we ARE told is that the average temperature (measured orally) is 98.6°F. this IS an accurate statement, because it is a direct conversion from the 37° C figure that was arrived at as an average temperature for a normal, healthy human. And certainly one could determine an "average" (meaning median or mode, depending) temperature for a given sample of humans to the level of a single digit past the decimal; thermometers are certainly accurate to that extent in measuring human body temperature either orally or rectally (or any other way).

Really.

Which is more credible?

• That the true & perfect statistical average is within a 20th of a degree Fahrenheit, or
• that given a typical variation of over 3 degrees Celsius (over 5 degrees Fahrenheit), Mr Celsius used a whole number in the middle of the range & considered further significant digits meaningless?

Good grief! What would Ockham say?

As for whether or not it is a "joke", frankly, I am quite happy with the difference between the two scales. I can tell in my own house when the temperature has risen or fallen a single degree Farenheit, which means that it's obviously of some use to know the difference between 71 and 72 degrees.

OK, so you have finely tuned temperature sense. You could then sense a shift of half a degree Celsius. That doesn't change the fact that human body temperature varies more than a degree within a single body, & ambient temperature varies even more widely than that within a room, & even more from one side of a street to another. Your thermometer is showing a precise temperature where it is, which has a deviation of a couple of degrees from where you are. It's interesting detail, but it's sort of excessive.

And I like Fahrenheit, with its arbitrariness & non-decimal significant points, & sort of feel the "100° = body temperature" has a weird animal elegance that basing a scale on the boiling temperature of water lacks. But I know this is mere cultural prejudice, & I think people protest too much on its behalf.

[DSYoungEsq]

Originally Posted by foolsguinea

Really.

Which is more credible?

• That the true & perfect statistical average is within a 20th of a degree Fahrenheit, or
• that given a typical variation of over 3 degrees Celsius (over 5 degrees Fahrenheit), Mr Celsius used a whole number in the middle of the range & considered further significant digits meaningless?

Good grief! What would Ockham say?OK, so you have finely tuned temperature sense. You could then sense a shift of half a degree Celsius. That doesn't change the fact that human body temperature varies more than a degree within a single body, & ambient temperature varies even more widely than that within a room, & even more from one side of a street to another. Your thermometer is showing a precise temperature where it is, which has a deviation of a couple of degrees from where you are. It's interesting detail, but it's sort of excessive.

And I like Fahrenheit, with its arbitrariness & non-decimal significant points, & sort of feel the "100° = body temperature" has a weird animal elegance that basing a scale on the boiling temperature of water lacks. But I know this is mere cultural prejudice, & I think people protest too much on its behalf.

You totally miss the point about accuracy.

98.6 is EXACTLY equal to 37. The accuracy of 37 is what is in issue, but when we accept that 37 is the statistical average, then it is equally accurate to say the 98.6 is the same statistical average. It would be highly improper to assert that 99 was the same statistical average, because it would NOT be.

Now, if the measurements upon which the assertion was based had been done with the Farenheit scale, we might well assert something like 98 or 99 as the "average human body temperature taken orally." But it wasn't. So get over it.

[Chronos]

Here's the problem: 98.6 may be accurate, but it's not precise. Or at least, it's not as precise as the number of digits implies. If I say that a particular temperature is 98.6 degrees, then I mean that it's somewhere between 98.55 and 98.65. If, on the other hand, I say that a particular temperature is 37 degrees, then I mean that it's somewhere between 36.5 and 37.5.

The mistake here is similar to that of the museum janitor, who says that a particular fossil is 65,000,003 years old, because he heard it was 65 million years old when he started working there, and he's been there for three years now.

[John W. Kennedy]

Strictly speaking, it's not "not precise", but too precise -- that is, it's more precise than is the reality it claims to represent.

To make this a bit easier to explain, though, could we get a sigma or so to use in giving examples?

[Aimew]

Originally Posted by GreenWyvern

I thought that the significance of the number 180 was so immediately obvious that it didn't need any further comment. Obviously, I was wrong. Ever use a protractor? Ever hear the expression "180-degree turn" ?

The numbers 60, 180, 360 have been used for divisions of time and space for thousands of years.

You noticed that 180 is divisible by 10. If you wok it out, you'll find that it's actually divisible by 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 36, 45, 90. That's why it's useful, especially if you don't have a calculator.

My point is that the article is wrong.

Fahrenheit based his scale on the freezing point of water and the boiling point of water, nothing else. He set the difference as 180 - an obvious number to anyone familiar with geometry or astonomy. He then made the starting point 32 degrees further down in order to avoid negative numbers, which were still quite esoteric to ordinary people at that time.

This is the story I have heard for most of my 63 years.
I think I first found it in one of Asimov's non-fiction books on physics when I was a young man, in my twenties, I think.
I was surprised that Cicil didn't seem to know that one; he is usually quite accurate. Oh well, nobody is perfect; but he comes closer than most.

[Exapno Mapcase]

Originally Posted by Aimew

This is the story I have heard for most of my 63 years.
I think I first found it in one of Asimov's non-fiction books on physics when I was a young man, in my twenties, I think.
I was surprised that Cicil didn't seem to know that one; he is usually quite accurate. Oh well, nobody is perfect; but he comes closer than most.

To my surprise, Asimov honestly did say this. It's in his essay, The Height of Up," from Oct. 1959 F&SF and reprinted in View from A Height and Asimov on Physics.

I don't even have to type it all out, because David Simmons did it in this 2004 thread:

Originally Posted by David Simmons

Here is Isaac Asimov's take on the 180^o difference and the Fahrenheit temperature scale in general. It's from his essay The Height of Up. By this account Fahrenheit originally set his high mark at body temperature of 12 but changed it to 96 because his thermometer was capable of greater accuracy than had been the case until then. On this scale freezing water was a little under 32 and boiling water was a little under 212, with a difference of not quite 180^o. Fahrenheit possibly liked 180 exactly and since it was so close that that anyway, he changed his reference points to two physical phenomena of water. He set the freezing point at exactly 32 and the boiling point exactly 180 away at 212. This made body temperature 98.6, but that's not a constant and only approximate anyone so it doesn't matter.

I can't find any reference to Fhrenheit setting body temperature at 100.

"But then, in 1714, a German physicist named Gabriel Daniel Fahrenheit made a major step forward. The liquid that had been used in the early thermometers was either water or alcohol. Water, however, froze and became useless at temperatures that were not very cold, while alcohol boiled and became useless at temperatures that were not very hot. What Fahrenheit did was to substitute mercury. Mercury stayed liquid well below the freezing point of water and well above the boiling point of alcohol. Furthermore, mercury expanded and contracted more uniformly with temperature than did either water or alcohol. Using mercury, Fahrenheit constructed the best thermometers the world had yet seen.

With his mercury thermometer, Fahrenheit was now ready to use Newton’s suggestion^*; but in doing so, he made a number of modifications. He didn’t use the freezing point of water for his zero (perhaps because winter temperatures below that point were common enough in Germany and Fahrenheit wanted to avoid the complication of negative temperatures). Instead, he set zero at the very lowest temperature he could get in his laboratory, and that he attained by mixing salt and melting ice. Then he set human body temperature at 12, following Newton, but that didn’t last either. Fahrenheit’s thermometer was so good that a division into twelve degrees was unnecessarily coarse. Fahrenheit could do eight times as well, so he set body temperature at 96.

On this scale, the freezing point of water stood at a little under 32, and the boiling point at a little under 212. It must have struck him as fortunate that the difference between the two should be about 180 degrees, since 180 was a number that could be divided evenly by a large variety of integers including 2, 3, 4, 5, 6, 9, 10, 12, 15, 18, 20, 30, 36, 45, 60 and 90. Therefore, keeping the zero point as was, Fahrenheit set the freezing point of water at exactly 32 and the boiling point at exactly 212. That made body temperature come out (on the average) at 98.6°, which was an uneven value, but this was a minor point.
Thus was born the Fahrenheit scale, which we, in the United States, use for ordinary purposes to this day. We speak of “degrees Fahrenheit” and symbolize it as “O F.” so that the normal body temperature is written 98.6° F."


* In 1701 Isaac Newton suggested that the temperature scale start with the temperature of melting ice as the zero point and the body temperature at 12.

Well, that should take Asimov's reputation down a peg.

[Aimew]

Originally Posted by DSYoungEsq

Well, they weren't arrived at by worrying one jot about the number 180. First of all, just because it's a cool number is meaningless. Unlike some things (hours of a day, e.g.), it isn't important to be able to divide a temperature difference up into parts like that. What purpose would it serve? Second of all, we have no evidence that 180 was in their thinking. We DO have evidence that the adjustment was made simply to allow for an "easy" conversion factor, given that 32° F was going to stay as the freezing point of water. In short, they looked at the scale as calibrated by Farenheit, which had no easy conversion factor, and they said, "Hey, you know what? If we set the boiling point at 212°, we can use 9:5 as a conversion factor!" The only part 180 played in this was the fortuitous happenstance of being 9/5ths of 100.

I'm glad you dropped by; we always enjoy new vict..., er, that is, new guests. However, if you decide to stay, you will quickly find that what you did here, which is simply speculate on an answer, based on what seemed to be a good idea to you, simply isn't an acceptable method of proof here. We like to rely on things like evidence (when we aren't relying on our own big egos ).

Fahrenheit was looking for a scale for his thermometer for meteorological purposes. The 180, while being a convenient number in and of itself, also allowed for fine measurements for the outside temperature. He (supposedly) added 32 to avoid (most) negative numbers as lay people didn't understand them readily.

[TriPolar]

Originally Posted by Aimew

Fahrenheit was looking for a scale for his thermometer for meteorological purposes. The 180, while being a convenient number in and of itself, also allowed for fine measurements for the outside temperature. He (supposedly) added 32 to avoid (most) negative numbers as lay people didn't understand them readily.

Yes. Fahrenheit is very useful for the temperature range found in most of the temperate zone. I recall he did make adjustments to get the 180, and other points. For instance his original 100F was human body temperature. But that left a fractional number for the boiling and freezing points. It was easier to set those as integers and leave body temperature fractional (and body temperature isn't as consistent as boiling and freezing anyway).

[John W. Kennedy]

Asimov was a biochemist, not a historian; I dare say he relied on secondary sources.

[Exapno Mapcase]

Originally Posted by John W. Kennedy

Asimov was a biochemist, not a historian; I dare say he relied on secondary sources.

That's not the issue here. Of course he relied on secondary sources, but he should damn well have understood the point made by RedSwinglineOne, that the divisibility of 180 is meaningless when applied to temperature on a non-absolute zero scale. What probably happened is that he was thinking about five other essays he was working on that did make a point about the divisibility of 180 and why 360 was a favorite number of the ancients and just automatically copied it into a place where it was more than irrelevant.

[John W. Kennedy]

As has already been pointed out, multiplication and division comes into the issue of making thermometers. (Don't try to catch me on absolute zero; I caught my 7th-grade science teacher on that one over half a century ago.)

[Exapno Mapcase]

Originally Posted by John W. Kennedy

As has already been pointed out, multiplication and division comes into the issue of making thermometers. (Don't try to catch me on absolute zero; I caught my 7th-grade science teacher on that one over half a century ago.)

I don't see it. What are you you referring to?

[gamerunknown]

Originally Posted by Exapno Mapcase

What are you you referring to?

I believe it was this post.

Originally Posted by russl5445

You take your brand new (unmarked) thermometer and measure human body temperature, and the temperature where water freezes. Make little marks on the thermometer for each. It's easy to then find the midpoint between the two marks - that's 64 degrees. You can then measure out exactly where 0 degrees should be. You then divide the regions in half, over and over. Since 32 and 64 are both powers of two, it's easy and accurate.

Seems like a "just so" story in the absence of any cites, especially due to the variability of human body temperature. If markings for each temperature were tied to the measure of body heat, then thermometer readings would vary quite widely. Unless there were some form of measurement concordance, where they marked where some other thermometer gave a reading of 96 degrees as 96 degrees on each new one.

[Exapno Mapcase]

Originally Posted by gamerunknown

I believe it was this post.



Seems like a "just so" story in the absence of any cites, especially due to the variability of human body temperature. If markings for each temperature were tied to the measure of body heat, then thermometer readings would vary quite widely. Unless there were some form of measurement concordance, where they marked where some other thermometer gave a reading of 96 degrees as 96 degrees on each new one.

That doesn't really apply to 180. You'd think 256 would be far more useful in that context. Or 128 for body temperature. And it's not what Fahrenheit or anybody did.

[TriPolar]

Fahrenheit designed a horse and ended up with a camel. He made adjustments to a concept to end up with something that had integer representations for the freezing and boiling points of water, under typical conditions. A lot of other niceties came along with the scale like the typical range of temperatures in a lot of the world on a scale of 0 to 100, numbers like 180 that some find handy, typical body temperature near 100. Fahrenheit may or may not have considered any of these factors, but historians should be accurate in reporting the known methodology for arriving at the scale though. But without these docudrama revisions of history Cecil wouldn't have many column topics.

[Kenm]

The Celsius scale has its shorcomings, not the least of which suggest that Anders Celsius was a few degrees short of body-normal temperature: He made the boiling point of water 0 and the freezing point 100. Also, Wikipedia:

What is often confusing about the Celsius measurement is that it follows an interval system but not a ratio system; that it follows a relative scale not an absolute scale. This is put simply by illustrating that while 10 °C and 20 °C have the same interval difference as 20 °C and 30 °C the temperature 20 °C is not twice the air heat energy as 10 °C.

Question: Could Asimov's reputation be saved if the 180° business, along with its many evenly divided numbers, mean that through their use in developing the scale Fahrenheit avoided Celsius's absolute-temperature failure?

BTW, The Wiki article needs an editor who could ask the author questions directly. It suffers from some strange syntax here and there, as if English is not the author's first language. If so, that may have introduced errors inadvertantly.

[Powers]

Originally Posted by Kenm

Question: Could Asimov's reputation be saved if the 180° business, along with its many evenly divided numbers, mean that through their use in developing the scale Fahrenheit avoided Celsius's absolute-temperature failure?

No; the only absolute temperature scale (that is, one in which a doubling of the temperature value represents a doubling in heat energy) in wide use is Kelvin, though it is at least a centigrade scale like Celsius is.


Powers &8^]

[John W. Kennedy]

Originally Posted by Exapno Mapcase

That doesn't really apply to 180. You'd think 256 would be far more useful in that context. Or 128 for body temperature. And it's not what Fahrenheit or anybody did.

Several thousand years of human history rather suggests that people prefer 180 to 128 (unless they’re computer professionals).

[Irishman]

Originally Posted by DSYoungEsq

the relevant text of which can be found here.

For clarity, it took me a moment to realize the relevant text is on the tab labeled "Sources". For some reason when I go to a link, I expect to be taken to the correct tab.

Originally Posted by DSYoungEsq

You totally miss the point about accuracy.

98.6 is EXACTLY equal to 37. The accuracy of 37 is what is in issue, but when we accept that 37 is the statistical average, then it is equally accurate to say the 98.6 is the same statistical average. It would be highly improper to assert that 99 was the same statistical average, because it would NOT be.

This entirely misses the point. "37" is the average to the ones place, but that says nothing about what numbers were actually used. Suppose Celsius took measurements ranging from 35.7 to 39.0 deg for human body, and then calculated an statistical average of 37.2 deg. However, he noted that the range was so broad that worrying about that 0.2 was rather pointless, so he conveniently dropped it and said "average human temp = 37".

If you take his actual calculated value to the same decimal precision as we use in Fahrenheit, then you have to start with the 37.2 deg.

(37.2 *9 / 5) + 32 = 98.96, which rounds for 3 decimal places to 99.0 deg F.

"37" could be any value from 36.5 to 37.4 and round to 37 when looking at 2 significant digits (or even degrees of Celsius). We have no information on the precision of Celsius's data for determining 37, so we cannot say if his numerical average was 37.000, or if it was 37.2 and he just decided 37 was more convenient.

Originally Posted by Powers

No; the only absolute temperature scale (that is, one in which a doubling of the temperature value represents a doubling in heat energy) in wide use is Kelvin, though it is at least a centigrade scale like Celsius is.

Centigrade meaning "the temperatures between water freezing and boiling points is divided into 100 equal increments). Yes, Kelvin scale uses Celsius degree divisions but moves the zero point to absolute zero.

The Fahrenheit equivalent is the Rankine scale - it uses Fahrenheit degrees but puts zero at absolute zero. In practice it probably isn't very widely used, other than for college student homework assignments.

[Exapno Mapcase]

Originally Posted by John W. Kennedy

Several thousand years of human history rather suggests that people prefer 180 to 128 (unless they’re computer professionals).

Not for temperature. No one in history pre-Fahrenheit did. Nor did he, really.

[John W. Kennedy]

Originally Posted by Irishman

The Fahrenheit equivalent is the Rankine scale - it uses Fahrenheit degrees but puts zero at absolute zero. In practice it probably isn't very widely used, other than for college student homework assignments.

It's in the CRC book, so I’m sure it was used somewhere once. So, I dare say, was the Réaumur scale (0˚= freezing, 80˚= boiling).

[Carl Pham]

Originally Posted by russl5445

FWIW, I heard a very reasonable explanation for the choice of 32 & 96 degrees: it makes it easy to build an accurate thermometer because 32 and 64 are both powers of two. This is important because the original thermometers would have been made by hand, not in a factory. So each thermometer would be a little different, and would have to be calibrated by hand.

You take your brand new (unmarked) thermometer and measure human body temperature, and the temperature where water freezes. Make little marks on the thermometer for each. It's easy to then find the midpoint between the two marks - that's 64 degrees. You can then measure out exactly where 0 degrees should be. You then divide the regions in half, over and over. Since 32 and 64 are both powers of two, it's easy and accurate.

At least, that's what I heard long ago.

This. Most definitely. In the 1600s everyone had to make his own instruments, and things we take for granted today, like accurate and precise rulers and tools, did not exist.

If you want an accurate and yet easy to carry thermometer, how on Earth are you going to divide the distance between two marks a few inches apart into 100 or 50 or 60 EXACTLY equal divisions? Without, remember, a precision ruler at hand? You can't.

On the other hand, dividing it into 32 or 64 equal divisions by repeatedly dividing accurately in two is easy. The Greeks knew how to divide distances very precisely in half using compass, scribe, and straight edge, and you can do pretty well with just a taut string. You don't need any precision measurement equipment, or tools.

As for the standard: Fahrenheit as a meteorologist probably already knew (and certainly those who adopted his scale widely later knew) that the boiling point of water varies significantly with weather, salinity and altitude, so as a practical standard for setting one end of the scale, it's useless. (The freezing point of water varies considerably less, because neither of the phases involved, ice or liquid water, is compressible. You still have the problem of salinity, but the effect is also smaller, and, if you come up from below -- melt ice -- it can be eliminated anyway, since ice is nearly salt-free.)

Human body temperature has the virtue that it's always at hand, it requires no equipment, and it doesn't vary with the weather or altitude. It's true it varies with individuals and even within an individual, but as long as you're not acutely ill, not much more than a degree or two.

Finally, God knows why anyone thinks a division of 100 equal parts makes intrinsic sense. I can only think it's a reflex carryover from the use of 100 equal parts in measurements of cost, length or mass, where you routinely multiply and divide such measurements, so as to calculate things like density, price per pound, area, volume, and so forth.

Now...can anyone think of ANY situation, other than using the ideal gas equation of state or calculating heat capacities (which isn't a very day to day experience), where you would want to multiply or divide by a temperature? Of course not. Or can anyone think of a case from daily life where you might want to define a prefix, as "kilo-" gets usefully added to "grams" or "meters?" What use would we have in ordinary 17th (or even 21st) century life for kilodegrees or millidegrees?

The most important property of a temperature scale, when people first started measuring temperature, largely for the purposes of weather prediction -- kind of important when 96% of the population makes its living by farming -- is that it's so straightforward, and requires so little equipment or training to implement, that even in an age when any instrument more precise than a piece of string or a balance scale cost a fortune and could only be made by master craftsmen in a major city, any yokel who could lay hands on the materials (glass, alcohol) could make one, calibrate it tolerably accurately, and understand how to communicate his results to others very clearly. (That last is a good reason to avoid negative numbers, given the level of math training then widespread. It's not like everyone had taken 7th grade algebra.)

By that criterion Daniel Gabriel Fahrenheit's scale was brilliant, and incidentally superior to Anders Celsius', which is why it is no accident that Fahrenheit's scale dominated world industry and commerce for centuries.

[John W. Kennedy]

Originally Posted by Exapno Mapcase

Not for temperature. No one in history pre-Fahrenheit did. Nor did he, really.

Thermometers had just been invented, so seeking for precedent there is useless. But there is clear precedent for numbers with a high selection of factors, such as 180.