The foregoing reflections were excited by seeing very recently some photographs from plaster casts of the forms of human beings as they had fallen and died when Pompeii and Herculaneum were destroyed by the first known and terrible eruption of Mount Vesuvius. The photographs alluded to reveal with a fearful fidelity the dreadful agonies of some of those who perished at Pompeii, and, while looking at the pictures, it is very difficult to divest the mind of the idea that they are not the works of some ancient photographer who plied his lens and camera immediately after the eruption had ceased, so forcibly do they carry the mind back to the time and place of the awful immurement of both a town and its people. That these photographs were not obtained from the lifeless forms of the Pompeiians the reader will readily understand, for their bodies have not been preserved entire from that day to this. The question then naturally arises, "How could plaster casts be obtained from which the photographs were produced?" To answer that question I must briefly explain that Pompeii was not, as is generally understood, destroyed by an overflow of red hot lava, which would have burnt up every particle of human flesh with which it came in contact almost instantly, without leaving a mould or impress of the form which it surrounded. The _black mud_ which flowed from Vesuvius into the doomed town of Pompeii entombed the houses and inhabitants--covered them up and formed a thick crust over them, which gradually hardened, and as the bodies crumbled away to dust a mould or matrix was left, from which plaster casts of great beauty and finish might have been obtained of almost everything that was destroyed. Unfortunately, this was not discovered until very recently, after many of the beautiful moulds had been destroyed by the process of hurried, thoughtless, and unsystematic excavation. It was only a short time ago, since Naples was united to Italy, that careful and intelligent excavation secured to future generations impressions from those matrices made by the most terrible process of natural mould making. Sig. Fiorelli, who was appointed superintendent of excavations at Pompeii, happily thought of obtaining casts from these natural moulds by pouring in soft plaster of Paris, and thus secure more useful mementos than by preserving the moulds themselves. Amongst the first casts thus obtained were the forms of four human beings, described as follows in the _Quarterly Review_ for 1864:--