Heavily-used Siemens Sieray Dual 500w MAT/V lamp - lit

Before any of you criticise the rather haphazard-looking setup I lashed up to run this lamp, I applied power to it thinking it would almost certainly be EOL, so for it to work was a complete surprise, and not bad considering the low amount I paid for this lamp! Oddly enough, the bimetallic switch that shuts off half the filament didn't seem to kick in, I ran the lamp for about 10 minutes and although the switch had visibly moved it had not moved quite enough to close the circuit.