Thanks to Amy, James and Matt (responded offlist). It looks like the 
best solution is to use the following without the brackets

[δ]

It looks like a perfect delta symbol on Safari for Mac, looks like a 
perfect delta symbol on Explorer for PC, and looks like an italicized 
delta on Explorer for Mac.
Cheers,
Bill


>Hi Bill -
>
>I don't know how much you look at the html source code itself (I 
>learned to make web pages by hand and so never got used to using 
>graphical programs routinely - but then I don't make very 
>complicated web pages), but I wonder whether Safari is overriding 
>the <font> tag that is sometimes used to change letters to symbols.
>I have always preferred instead to use the "HTML entities" for 
>characters, and have not noticed failures using them in Firefox, 
>which I think is becoming a preferred browser even for many former 
>Safari users now.  (www.mozilla.com; open-source, free, secure, and 
>lovely to use.)
>
>The web page below lists the acceptable html codes for Greek letters 
>and some other math symbols (no per mille, unfortunately).  In my 
>experience the decimal code is the most failsafe, but the "Entity" 
>codes are certainly easier to remember.  I just made a quick page 
>with all three versions of "delta" and Firefox could identify all 
>three correctly.
>
>http://www.htmlhelp.com/reference/html40/entities/symbols.html
>
>Hope this helps.
>
>Amy
>
>--
>
>.   #
>. Amy Myrbo
>. Core Lab Manager
>. Limnological Research Center
>. University of Minnesota
>. 500 Pillsbury Dr SE
>. Mpls MN 55455
>. 612-626-7889
>.f612-626-7750
>. [log in to unmask]
>. http://lrc.geo.umn.edu
>. http://www.myrbo.com


-- 
Dr. William P. Patterson
Associate Professor
Department of Geological Sciences
114 Science Place
University of Saskatchewan
Saskatoon SK S7N 5E2
Canada
Phone: 306-966-5691(office); 306-966-5712(lab)
Email: [log in to unmask]
Web: http://geochemistry.usask.ca/bill.html