Why are my HTTP resources treated differently than my HTTPS ones?

[Mike Spreitzer <ms...@us.ibm.com>]

I have Tomcat 3.2.2 in standalone mode serving both HTTP and HTTPS.  I 
have GIFs that appear on both the HTTP and the HTTPS pages.  I am viewing 
my site with both Netscape 4.75 and IE 5.0 on Win 2K.  Where the GIFs 
appear on HTTP pages, their create date, modification date, and file size 
are recorded in the browser's cache.  Where the same GIFs appear on HTTPS 
pages (the GIFs themselves are, in this case, fetched from HTTPS URLs), 
none of those things is recorded in the browser's cache.  Netscape's cache 
setting is "Document in cache is compared to document on network: Every 
time", and IE's cache setting is "Check for newer versions of stored 
pages: Automatically".  Changing IE's cache setting to "Every time you 
start Internet Explorer" and flushing its cache makes no difference.  When 
I change IE's cache setting to "Every visit to the page", and flush its 
cache, then IE starts remembering the HTTPS GIFs' create date, 
modification date, and file size.  For Netscape, changing the cache 
setting to "Document in cache is compared to document on network: Once per 
session" (and flushing the cache) causes the browser's cache to start 
remembering the create date, modification date, and file size (among other 
things) for the GIFs at HTTPS URLs.

What causes this differential treatment of HTTP vs. HTTPS resources for 
some browser settings?  Are there Tomcat configuration options that affect 
this?

Thanks,
Mike