Davy lamps and lies our teachers told us

Mining safety lamp
After writing about Davy lamps yesterday, i decided to have a go at drawing one from memory.
It turned out that the lamp in my memory was not actually a Davy lamp, but one that was further modified by somone called Stephenson - apparently the original Davy lamps were not very safe! So much for the Davy lamp saving the lives of thousands of miners- it seems that mine accidents increased since the metal mesh was not resistant enough. Oh well - another historical myth shattered.
The glass sheath around the mesh, added by Stephenson, increased the safety dramatically.

addendum - I've checked and it seems that the Stephenson referred to is the one famous for designing Stephenson's Rocket- a steam powered locomotive.