_I had once Thought to have carried these 〈Searches〉 farther; in Particular, besides what is occasionally mention’d in the last 〈Essay〉 concerning 〈Infection〉 in acute Diseases, to have enquired into the Nature of 〈Contagious〉 and 〈Hereditary Distempers〉. But the Humour of Scribling would not hold out; And some perhaps will say, ’Tis well enough it didn’t; For I am not Ignorant how Few I am like to Please; If it be hard to Think and Write Justly, ’tis harder yet to Bring Others to one’s own 〈Taste〉; Nor shall I be at all Angry, if to Many I have afforded Matter of 〈Satyr〉 and 〈Invective〉; Less Wit suffices for These than for the Discovery of Useful Truths. They who have no Smattering of 〈Mathematical〉 Knowledge, are incompetent Judges of what Service I have done towards the Improvement of the 〈Theory〉, or 〈Practice〉 of 〈Medicine〉, and Those who are acquainted with these Matters, will, it may be, think it something to Talk Intelligibly on such difficult and abstruse Points. I neither want 〈Applause〉, nor fear 〈Censure〉; and therefore be the Fate of These Papers what it will, as they were first Penn’d for my own 〈Satisfaction〉, and Innocent 〈Entertainment〉; so I am resolved They shall never Ingage me in the Trouble of 〈Quarrels〉 or 〈Disputes〉._ THE CONTENTS. ESSAY I. _Of the Viper._ _An Appendix containing Anatomical Observations, and an Account of some other Venomous Animals._ ESSAY II. _Of the 〈Tarantula〉 and Mad Dog._ ESSAY III. _Of Poisonous Minerals and Plants._ ESSAY IV. _Of Opium._ ESSAY V. _Of Venomous Exhalations from the Earth, Poisonous Airs and Waters._ [Illustration] ESSAY. I. OF THE VIPER.