Cindy McLeroy had suggested "the control key and roll the scroll
button on your mouse". I had tried that and concluded that it worked
with the Microsoft multi-button mouse but not with my mouse, the
Logitech mouse.
But the helpful answers got me to exploring my environment. Unlike
most of you, I use a Mac and read email via Apple's Mail, web pages
via Safari. I knew the Mac has long had features for people with
handicaps, but I had ignored the capability. I just corrected that
oversight. By turning on Universal Access zooming I suddenly had
everything I could ask for and more. Zowee! And now it works with
my Logitech mouse and across all applications!
Thank you, good people. I'm a happy puppy.
Alton