"Tony uk" wrote

How did that water get there?

The bulb blew out because the glass cracked and developed a slow leak. The
filament burned out as soon as there was enough oxygen to let it burn. The
continued leakage in to the low pressure gas filled bulb sucked rain water
in through the not perfectly fitting gasket. The gasket was tight enough
however, to hold the water in against the very low pressure head of it's
weight and the vacuum lock of the glass dome.

--
Roger Long