Sir, Every day produces some new publication relative to the late tremendous eruption of mount Vesuvius, so that the various phaenomena that attended it will be found on record in either one or other of these publications, and are not in that danger of being passed over and forgotten, as they were formerly, when the study of natural history was either totally neglected, or treated of in a manner very unworthy of the great Author of nature. I am sorry to say, that even so late as in the accounts of the earthquakes in Calabria in 1783, printed at Naples, nature is taxed with being malevolent, and bent upon destruction. In a printed account of another great eruption of Mount Vesuvius in 1631, by Antonio Santorelli, doctor of medicine, and professor of natural philosophy in the university of Naples, and at the head of the fourth chapter of his book, are these words: Se questo incendio sia opera de' demonii? Whether this eruption be the work of devils? The account of an eruption of Vesuvius in 1737, published at Naples by Doctor Serao, is of a very different cast, and does great honour to his memory. All great eruptions of volcanoes must naturally produce nearly the same phenomena, and in Serao's book almost all the phenomena we have been witness to during the late eruption of Vesuvius, are there admirably described, and well accounted for. The classical accounts of the eruption of Vesuvius, which destroyed the towns of Herculaneum and Pompeii, and many of the existing printed accounts of its great eruption in 1631 (although the latter are mixed with puerilities) might pass for an account of the late eruption by only changing the date, and omitting that circumstance of the retreat of the sea from the coast, which happened in both those great eruptions, and not in this; and I might content myself by referring to those accounts, and assuring you at the same time, that the late eruption, after those two, appears to have been the most violent recorded by history, and infinitely more alarming than either the eruption of 1767, or that of 1779, of both of which I had the honour of giving a particular account to the Royal Society. However, I think it my duty rather to hazard being guilty of repetition than to neglect the giving you every satisfaction in my power, relative to the late formidable operation of nature.