function isName(varchar) {
var str = varchar.value;

for (var i = 0; i < str.length; i++) 
{
var ch = str.substring(i, i + 1);
if (((ch < "a" || "z" < ch) && (ch < "A" || "Z" < ch)) && ch != ' ' && ch != ".") 
{
alert("This field will only accept letters.");
return false;
   }
}
return true;
}