The bells at the National Cathedral in Washington will no doubt be around for a long time. Not so the foundry that cast some of them, however. Turns out, it's that very foundry for which the CLOSING BELL tolls. Jim Axelrod has an appreciation: There is a certain timelessness inside London's Whitechapel Bell Foundry, where it could be the 21st century, or the 19th, or even earlier. Alan Hughes' family has…