Dear Bill, Thanks for sharing this with us. Your tone is polite, yet firm and informed.
In this single letter, I feel that you have done more to promote the use of SI than you could with a thousand angry and abusive letters. I have to admit that I am seriously considering stealing your words to use as a model to tone down some of my stronger diatribes. Cheers, Pat Naughtin LCAMS Geelong, Australia -- on 14/2/04 6:09 AM, Bill Hooper at [EMAIL PROTECTED] wrote: > Mr. Szesze: > > Mr. G. Stanley Doore directed me to your excellent metric pages of the > Montgomery County Public School web site starting at: > http://www.mcps.k12.md.us/curriculum/science/instr/metric.htm > I applaud your actions to prepare your students for the real world by > emphasizing metric measurements in your curriculum. > > I hope you will not object to my making a couple comments on the page > on unit symbols. My references are to the English version of the > official document entitled "The International System of Units (SI)" 7th > addition 1998 (and its 2000 supplement when necessary) published by the > Bureau International des Poids et Mesures (International Bureau of > Weights and Measures). > > Under "Mass" I find: > Mg=T = megagram = Tonne (metric) > which is not correct. The SI symbol for tonne is a lower case "t" not a > capital "T". (ref: page 105, table 6, "Non-SI units accepted for use > with the International System") > > The names of the units like tonne (and litre) are not proper names and > so should not be capitalized except where you would capitalize other > words (such as at the beginning of a sentence or in titles or when all > caps are used). > > Most people well versed in SI would recommend the spelling "metre" and > "litre" rather than "meter" and "liter". > > In the various places where exponents are needed, those exponents are > not written as superscripts, as they should be. Examples are the > symbols for cubic metre and cubic decimetre. Other examples are in the > list of all the prefixes. I admit that it is possible that your web > page DOES produce the required superscripts and that my web browser > just cannot reproduce them. > > (I can't produce the superscripts in my email message either, but I > would hope that your web page would be sufficiently sophisticated that > it could. Either that, or add a note explaining that such exponents > should be written as superscripts even though your software is not > capable of doing so. I often use the caret mark (^) to indicate > exponentiation, thus: m^3 for cubic metres and 10^-6 for ten to the > minus 6 power.) > > Under SI Base Units, the word length is misspelled, a purely > typographical error, apparently. > > Under SI Prefixes, I find: > 10 -6 micro u > in which the symbol is not correct. The symbol for 10 to the -6 power > is the lower case Greek letter mu, not the lower case Latin letter "u". > The l.c. mu looks like this � (I hope). I have produce it correctly > on my copy of this email message but I cannot guarantee the you will > receive it correctly. That is unfortunately the case for a number of > special characters when they are transmitted from one computer to > another by email or internet. > > I am curious about your choice of prefixes to show in your list. It is > not complete although it is so long that it appears that you intended > it to be complete. It is missing the prefix and symbol for 10 to the > plus 24th power, which is yotta (symbol: capital Y). Also missing are > the prefixes for 10 to the minus 21st power and 10 to the minus 24th > powers. They are zepto (symbol: lower case z) for 10^-21 and yocto > (symbol: lower case y) for 10^-24. (Ref: page 103, Table 5, "SI > prefixes") > > I hope my comments above are helpful. I'm sure you agree that those of > us who are responsible for teaching the SI system need to be especially > diligent about getting the details correct. > > William Hooper > Certified Advanced Metric Specialist
