HT>> 100*10^-(23.2801+(-5287.32/("Dry Bulb"+459.4)))*("Dry
 HT>> Bulb"+459.4)^4.9283
 HT>> *(10*(23.2801+(-5287.32/("Wet Bulb"+459.4)))
 ml> ====-----^

 ml> that * should be a ^ ;) you were right, it was a typo
 ml> ;)

You found it!  Thanks.

What I'm really doing is using software that generates cell entries in
spreadsheet-like columns.  It fills the cells in those columns with
readings it gets from sensors.  The user can create new columns and, just
like in a spreadsheet, put formulas in the cells of those columns.  So,
I've got two electronic temperature sensors connected, one in a wet sock,
measuring the wet and dry bulb temperatures every 12 minutes (and thus
generating an additional row every 12 minutes).  Of course, it can also
display graphs of the data.  And it has other nice display features as
well.  Since I had a pressure sensor I connected it, too, and so I should
be getting values for the relative humidity that are more accurate than the
tables (which I presume they generate by assuming the pressure is one
standard atmosphere).  My limitation is now getting a true, fully
depressed, wet bulb temperature.  Something I now have the motivation to
work on improving!

If you're interested they have a great web site (www.vernier.com).  The
software is called LoggerPro and the computer interface I'm using is
LabPro.  The temperature sensors are TMP-BTA and the pressure sensor is
BAR-BTA.  It's a great company, too, as they (and I swear this is true) are
more interested in providing good service than in making larger profits! 
They're stuff is so cool they've collaborated with Texas Instruments and
made their LabPro compatible with the TI graphing calculators.  The LabPro
has flash memory for storing data, but it can also be used to extend the
memory of your TI calculator.  Neat stuff for people who like to write lots
of programs on their TI calculators.

Their main competitor is Pasco (www.pasco.com) which is a company with
(almost) exactly the opposite philosophy.  They make a lot of very great
stuff, but they are pricey and are often the only source.

There're some guys (www.mathmachines.com) who write programs for their TI
calculators and then use them to control things like servo motors, RC cars,
and even their very own robot.

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