using include() on a compressed file

I've got a file in a htaccess protected directory, that I want to have downloaded by people authenticated through a mysql database.

the problem that when I use include ("somedir/file.tar.gz"); the result is displayed binary rather than a download prompt.

any suggestions?

Alternately I've tried including a html file from the same directory, and have it redirect to the file in question. this ends up giving the expected login pop-up.. (I thought I could embed the authentication into the redirect link.. NOPE! heh)