Page:Passages from the Life of a Philosopher.djvu/230

214 opened. Captain Kater and myself entered, and they were then closed upon us. The further corner of the room, which was paved with squared stones, was visibly of a dull-red heat. The thermometer marked, if I recollect rightly, 265°. The pulse was quickened, and I ought to have counted but did not count the number of inspirations per minute. Perspiration commenced immediately and was very copious. We remained, I believe, about five or six minutes without very great discomfort, and I experienced no subsequent inconvenience from the result of the experiment.

I have never been so fortunate as to be conscious of having experienced the least shock of an earthquake, although, when a town had been destroyed in Ischia I hastened on from Rome in the hope of getting a slight shake. My passion was disappointed, so I consoled myself by a flirtation with a volcano.

The situation of my apartments during my residence at Naples enabled me constantly to see the cone of Vesuvius, and the continual projections of matter from its crater. Amongst these were occasionally certain globes of air, or of some gas, which, being shot upwards to a great height above the cone, spread out into huge coronets of smoke, having a singular motion amongst their particles.

A similar phenomenon sometimes occurs on a small scale during the firing of heavy ordnance. I have frequently seen such at Plymouth and elsewhere; but I was not satisfied about the cause of this phenomenon. I was told that it occurred more frequently if the muzzle of the gun were rubbed with grease; but this did not always succeed.

Soon after my return to London I made a kind of drum, by