To prove that light and heat are present there.
The pear-shaped vacuum globe, I understand,
Is far too hot to fondle with the hand.
While, as is patent to the meanest sight,
The carbon filament is very bright.
As for the lights they hang about the town,
Some praise them highly, others run them down.
This system (technically called the Arc),
Makes some passages too light, others too dark.
But in the house the soft and constant rays