The temperature remained what it had been during our passage through the lava and schists.

Only my sense of smell was forcibly affected by an odour of protocarburet of hydrogen.

I immediately recognised in this gallery the presence of a considerable quantity of the dangerous gas called by miners firedamp, the explosion of which has often occasioned such dreadful catastrophes.
Happily, our light was from Ruhmkorff's ingenious apparatus.

If unfortunately we had explored this gallery with torches, a terrible explosion would have put an end to travelling and travellers at one stroke.
This excursion through the coal mine lasted till night.

My uncle scarcely could restrain his impatience at the horizontal road.