The insertion of additions and improvements in the title of new editions of books, has been too generally, though sometimes justly, understood as little else than a contrivance of the bookseller, to animate a languishing sale; but this is far from being the case in respect to the works of our author, whose maturer sentiments on many of the subjects, he had before treated of, cannot be well comprehended, unless by a careful perusal of his later corrections, seeing the alterations he has thought fit thereby to make in his earlier productions, are not less necessary to be attended to by the prudent practitioner, than they are really interesting to the unhappy patient: the truth of which cannot be more manifestly evinced, than by his last publication of his essays on poisons; wherein he entirely subverts his former hypothesis, and builds his reasonings upon a new foundation; he also tacitly admits his former experiments to have been too precipitately made, and the conclusions deduced from them, to have been too hastily drawn.
To illustrate what has been advanced upon this head, it will not be improper to observe, that when Dr. Mead first wrote these essays, he was of opinion, “That the effect of poisons, especially those of venemous animals, might be accounted for, by their affecting the blood only: but the consideration of the suddenness of their mischief, too quick to be brought about in the course of the circulation, (for the bite of a rattle snake killed a dog in less than a quarter of an hour)[6] together with the nature of the symptoms entirely nervous, induced him to change his sentiments,[7]” and to conclude, that the poison must be conveyed by a medium of much greater quickness, which could be no other than the animal spirits.
From hence our author is led to prefix to the last edition of this performance, an inquiry into the existence and nature of this imperceptible fluid, with which we have been but very imperfectly acquainted. He has also added several new experiments, tending to confirm this theory, and explain the properties of the viperine venom, particularly by venturing to taste it; at the same time he has likewise contradicted some of those he had formerly made, whereby he had been induced to believe, this poison partook of a degree of acidity: for instance, he formerly asserted that he had seen this sanies, “as an acid, turn the blue tincture of heliotropium, to a red colour;[8]” whereas his more modern trials convinced him, it produced no alteration at all.
The essays on the tarantula and mad dog, are likewise considerably enlarged in the last impression; especially the latter, in which is now comprehended a regular and elegant history of the symptoms attending the bite of this enraged animal, the reason of the consequent hydrophobia, and more extensive directions for the cure: also an accurate description of the lichen cinereus terrestris, its efficacy, and manner of acting. A composition of equal parts of this plant and black pepper, was inserted, at our author’s desire, into the London dispensatory, in the year 1721, under the title of pulvis antilyssus, which he afterwards altered by using two parts of the former, and only one of the latter, as it now stands: in 1735 he also recommended the use of this medicine in a loose sheet, intitled, a certain cure for the bite of a mad dog.
In treating of poisonous minerals, exclusive of what is added concerning mercurial unctions, our author has given a new analysis of the antient and modern arsenic; and his essay on deliterious plants, has afforded him an opportunity of enquiring into the cicuta, so much in use of old for killing, especially at Athens, and which is said to have been administered to Socrates in consequence of his condemnation. To this he has likewise subjoin’d an appendix, concerning the mischievous effects of the simple water distilled from the lauro-cerasus, or common laurel, which were first observed some years since in Ireland, where, for the sake of its flavour, it was frequently mixed with brandy.—His observations upon venemous exhalations, are not less extended, nor ought the, as well useful as ornamental, plates added to this last edition, to pass unnoticed, particularly, “The anatomical description of the parts in a viper, and in a rattlesnake, which are concerned in their poison,” by our great anatomist the learned and ingenious Dr. Nichols.
In 1703 Dr. Mead communicated to the royal society, a letter published in Italy in 1687 (a copy of which he met with in the course of his travels) from Dr. Bonomo to Seignor Redi, containing some observations concerning the worms of human bodies;[9] whereby it is intended to prove, that the disease, we call the itch, proceeds merely from the biting of these animalcules: this opinion is espoused by our author in one of his latest performances,[10] wherein therefore he directs only topical applications for the cure of this troublesome disease.
The proofs our young physician had already given of literary merit, recommended him soon after the above-mentioned communication, to a seat among that learned body; in the same year he was also elected one of the physicians of St. Thomas’s hospital, and was employed by the surgeons company to read anatomical lectures at their hall, which he continued to do for some years.
In 1704 appeared his treatise de imperio solis ac lunæ in corpora humana, & morbis inde oriundis. At this time the Newtonian system of philosophy, from whence our author had chiefly deduced his reasonings upon this abstruse subject, were neither thoroughly understood, nor universally received: nevertheless whatever cavils were raised against his hypothesis, it was generally admitted, that his observations had their uses in practice.
The doctor thought proper to revise this juvenile production, and to give a new edition of it in 1748; when he not only altered the disposition of some of the old, but also introduced more than a little new matter into that work: particularly he has placed some mathematical points in a clearer light, than they before appeared; he has entered into the discussion of “a difficult question, which has raised great contention among philosophers: viz. whereas water is more than eight hundred times heavier than air, how does it happen, that the latter when replete with watery vapours, depresses the mercury in the barometer; so that its fall is an indication of rain?[11]” he has also enquired into “the weight of the atmosphere on a human body, and its different pressure at different times;[12]” and he has illustrated and confirmed the medicinal part by several additional observations and cases, that promise real utility to the practice of physic. To the whole is now first adjoined a corollary tending to strengthen his reasonings upon the subject, by observations of the effects of storms on the human body; wherein, from the case of a lady who was seized in an instant with a gutta serena, (that rendered her totally blind) on the night of the great storm which happened in 1703, he is led to give a distinct account of the cause and cure of that melancholly distemper. This work is also remarkably distinguished by many curious observations our author received from his ingenious preceptor in the art of healing, Dr. Pitcairne.
Our author’s distinguished genius for, and sedulous attention to the interests of his profession, procured him an acquisition of farther honours, as well as recommended him to the patronage of the most eminent of the faculty: in 1707 his Paduan diploma for doctor of physick, was confirmed by the university of Oxford; in 1716 he was elected fellow of the college of physicians, and served all the offices of that learned body, except that of president, which he declined when offered to him in 1744. Radcliff, the most followed physician of his day, in a particular manner espoused Dr. Mead, and in 1714, upon the death of the former, the latter succeeded him in his house, and the greater part of his practice; some years before which, he had quitted Stepney, and had resided in Austin Fryars.