Old style 40w and 60w incandescent light bulbs (Weston Underwood DE6)

Hi, I need a supply of these bulbs which individually fit into a device that was constructed to keep the bell ringing ropes in our church belfry dry. (When switched on, the device creates and concentrates a gentle heat which does the job). The nature of these bulbs means they are prone to give up frequently). Hence I am trying to stock up. Thank you