bName = navigator.appName;
bVer = parseInt(navigator.appVersion); 
if      (navigator.platform == "Win32") ver = "pc";
else if (navigator.platform == "MacPPC") ver = "mac";
if (ver == "pc") {document.write('<a href=javascript:print()><IMG SRC=http://www.pbs.org/wnet/brain/images/footer_07.gif WIDTH=141 HEIGHT=19 alt=Print this page. border=0></a>')}
if (ver == "mac") {document.write('<IMG SRC=http://www.pbs.org/wnet/brain/images/spacer.gif WIDTH=141 HEIGHT=19 border=0>')}