If I may be permitted to add my own anecdote about fire starting: I have a glass magnifying lens that I use to light my pipe with (tricky, when you can't hold the pipe in your mouth and see inside the bowl for the correct distance and angle for the lens). While at an encampment a few years ago I decided to experiment to see how well gunpowder could start a cooking fire, and I chose my lens to see if I could ignite the powder with it. I had to lay my carronade ball shaped body down close to the fire pit to be able to get the lens in close enough. So here are the results:
Does it work?
YES IT DOES.
How long does it take for the lens to ignite the gunpowder?
EXACTLY 3 SECONDS.
What was the result?
Well there was a great whoosh and eruption and smoke and such much like an old time camera flash in a wild west movie. I can now say I have much in common with Wile E Coyote, for I am now both a super-genius and my face was covered in the inevitable cartoonish black soot like some Acme powered anti-road runner death machine exploding on ol' Mr Coyote. Fortunately I was wearing my spectacles at the time, so no permanent damage done and also no need to shave for the rest of the weekend.
Recreate experiment at your own peril.