Page:Passages from the Life of a Philosopher.djvu/241

Rh I shut my eyes, and after perhaps another minute, again saw the image in its lower position. It then rose to its former position, vibrated, and shortly again descended: it remained down for some time and then resumed its first position.

An opportunity presented itself several years after my examination of Vesuvius of witnessing another form under which fire occasionally exerts its formidable power.

I was visiting a friend at Merthyr Tydfil, who possessed very extensive coal-mines. I inquired of my host whether any fire-damp existed in them. On receiving an affirmative answer, I expressed a wish to become personally acquainted with the miner's invisible but most dangerous enemy. Arrangements were therefore made for my visit to the subterranean world on the following day. Professor Moll of Utrecht, who was also a guest, expressed a wish to accompany me.

The entrance to the mine is situated in the side of a mountain. Its chief manager conducted our expedition to visit the 'fire-king.'

We found a coal-waggon drawn by a horse, and filled with clean straw, standing on the railway which led into the workings.

The manager, Professor Moll, and myself, together with two or three assistants, with candles, lanterns, and Davy-lamps, got into this vehicle, which immediately entered the adit of the mine. We advanced at a good pace, passing at intervals doors which opened on our approach and then instantly closed. Each door had an attendant boy, whose duty was confined to the regulation of his own door.

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