The Air being most essential to Animal Life, many useful Experiments and noble Enquiries have of Late Years been made by Philosophers, and much written by them on its Nature and Properties; and we have several Histories of its different Effects at sundry Times, in various Places, on human Bodies, and what beneficial or hurtful Alterations it's many Vicissitudes have made on them. But what several and different Effects the fame Kind or ConstitutionA body of fundamental principles and established precedents by which a state governs itself; or the composition of something. of the Weather and Seasons may produce at their sundry Returns, has not yet been so well attended to and examin'd as the Extent and Usefulness of the Subject demands; nor could it possibly 
p.vi be done whilst these Scraps of Histories lay scattered in a vast Multitude of Authors of different Designs and Professions, as Historians civil, ecclesiastical, and political; Physicians, Divines, Naturalists, Monks, Fryars, Journalists, Travellers, &c. And while they lay dispersed so wide in an endless Number of Books, and frequently in small Fragments, we must remain entire Strangers to the only true, valuable, and proper Use of them, so highly and inestimably beneficial to Mankind. For who could be the better for Thousands of Volumes of Histories of the Effects of different Seasons, Weather, and Constitutions of the Air, which though they mention the Effects supervening each several Season, yet take no notice of the different Effects of similar Constitutions, with the various prosperous, or unsuccessful Treatment of each Species? This could neither be expected nor done, but upon an exact judicious Review, and tedious Rumination of a large Collection of goodp.vii Histories, and thereby drawing from the Whole, such Deductions, Inferences, Aphorisms, or Conclusions, as might be of general Service, and point out just Rules for the certain, laudable, and salubrious Treatment of such Effects. This is what is here attempted when they shall happen for the future. Another subordinate but more extensive Use thereof is, that by comparing what has happened for so many Ages past, We may make some tolerable Guess what we may probably expect the next Season or Constitution to be.
A particular continued History of this Kind over the Globe, for a long Series of Years, is not to be expected, however much it may be wanted and desired. For 1. A great Part of the inhabited World is yet unknown to us, and consequently their Weather and Seasons must. 2. The greatest Part of the American, African, and Asiatic Nations, are ignorant and illiterate, except what they have learned of late p.viii from CommerceThe activity of buying and selling of goods and services. and Acquaintance with Europeans. Now their Stay has been too short in those Places, to compile such Histories and Observations; and the barbarous Natives are unqualified for it, as they never received any such, nor any Helps for them, from their Ancestors. 3. Where any Degree of Learning has been preserved, restored, or lately acquired, the Generality of People have been too idle to collect: such Histories, not being apprized of their great Worth and Use to all People who breathe in the Air, are fed by the Products of the Earth, and have Bodies to be influenced by the Vicissitudes and Alterations, or Extremes, good or bad, of Weather and Seasons. 4. Ancient Observations of this Kind, are either long since lost themselves, or the Languages, and perhaps Letters, in which they were written, are not now known, or are so much changed, that few, is any of the descendant Natives themselves, understand them. Where are now the p.ixAstronomical Observations of the ancient Ægyptians, Chaldeans, and Babylonians, the Alexandrian and Roman famous Libraries, most of the Learning of Greece, Solomon s natural Histories &c. Who now understands, or can be benefited by the numerous ManuscriptsBooks, documents, or piece of musics written by hand rather than typed or printed. Later, pieces of work that have not yet been published. of the ancient Brachmans which they treasured up in their Cells, but which cannot now be read by their Posterity? And since the Revival of Learning and the Invention of Printing in Europe, such Scraps as are preserved, or published, are dispersed in so many different Authors and Languages, that they are past one Man's Procuring, Understanding, and Perusal, especially with the Time, Judgment, and Attention, requisite to draw any certain Deductions from them. 5. Many that are publish'd are so stuft with Theory, that they seem only intended to support a favorite Hypothesis. From all which we see, that an universal History of this kind is impossible.
p.x Practice must still be improved by exact and judicious Observations of Authors, both ancient and modern, to which our own can only be adding a Mite. From these, Physick took its Birth, and by these has made its chief Progress not from Philosophy or Imagination. A close Attention to Nature, justly raised the Name of the great Hippocrates above his PredecessorsPeople who held a job or office before the current incumbent., Contemporaries, and Successors. By this he acquired his Knowledge, Honour, and Usefulness; not by Contempt of the Ancients, espousing some darling Hypothesis; nor by wasting his Time in Studies or Pleasures foreign to his Profession: He despised such mean Artifices to gain popular Esteem. He found enough in his Profession to employ his Time, and take up the most capacious Human Intellect. And tho' he wanted the Help of our late Mathematical Gauges for measuring the Gravity, Levity, Elasticity, Heat, Cold, Moisture, Dryness, &c. of the Air; yet he from his Senses, made morep.xi accurate Observations on it, and its Effects, than have been made since. But in making Deductions from Facts faithfully and accurately narrated, all Imposition, Error, and Mistakes, should be watchfully avoided; and let only Things clear and useful be collected, without omitting or concealing any essential Things or Circumstances, or rashly glossing them over with Theories of our own, and so drawing hasty, dubious, impertinent, or false Consequences from them. To avoid which, Reason and Observation must go together the latter without the former, makes an Empiric; and the former without the latter, makes a conceited, wrangling, contentious Disputant about Words, and is the more unsuccessful and dangerous of the two. Nei ther of these search out the Truth of Causes from their Effects, in order to prove and confirm, or reject Things by Experience and Observation, which alone must be of the most extensive Benefit during a Reign of Epidemics,p.xii whose Rise, Spread, Duration, and fatal Consequences, are mostly so quick, their Symptoms and Cure (even of the fame Species of Disorders, but from different Causes] most different and opposite. A Collector must not only take Care to avoid imperfect and wholly lame Scraps of Passages, but also superfluous and trifling Things; and though he be obliged profitably to converse a good deal with ancient Monks and Friars, yet let him not meddle in disposing (as they too often and weakly did) of the Almighty's Arrows and Judgments; nor with their superstitious Stories of Padfoots and Barguests, Apparitions, Hobgoblins, and Dæmons, invented only to serve mean Purposes. Nor are some later, otherwise learned and eminent Men, clear from this Charge, who often made such pitiful Stuff a Part of the Religion of their Times. Nor should he pay the Infidel the Compliment of ridiculing and contemning some special Premonitors of divine Displeasure. Nor should hep.xiii pay any Regard to judicial Astrology, Nor will he often find such in solar and lunar Eclipses, Conjunctions and Oppositions of Planets, and such Things as happen several Times every Year; and which have been industriously prostituted to contemptible Purposes, by furious and disaffected Party-Men in Church and State, in several Ages, to inflame the Populace. Nor need he spend much Time about the Plague, exclude of other Distempers, as it is no one Disease that goes by that Name, but many; and most likely others in proper Situations, by Assistance of Libraries and Conversation with learned Men, have made considerable Collections of its Visitations.
Besides all the former Part of this Work, the Reader has in the latter Part, a general History of the Air and Weather, and their most remarkable Effects in Several Places (and often at the same Time) for about 250 Years last past, with very few Chasms; which 'tisp.xiv hoped, together with the general and particular Remarks and Deductions from the whole, may be of some Benefit to Mankind. Whatever Reception this attempt may meet with from the World, the Author is conscious it was well in tended, was much wanted, is the first of its Kind; and would be heartily sorry to find his many Years indefatigable Toil in compiling it, to be useless.
This History though short for the Length of Time, and Usefulness of the Subject, clearly shews and proves the Effects of good or bad Air and Seasons on Animal Bodies; but being a History, it is confin'd to Facts: But such as would understand the Reason of such Effects, or a mechanical Account of their Productions, will meet with it in the Observations on the English Bills of Mortality, which is now in the Press, and will speedily be published; a most useful Work, suited and adapted to the Taste, not of the medical Faculty only, but of allp.xv Scholars, Gentlemen, Naturalists, and Persons of Taste. The Author has had it on the Anvil for 18 Years, especially the last four, wherein it has been his sole Study, except what small Time he could spare towards the carrying on and finishing this History, which has also been 16 Years in collecting and compiling, and making Deductions from it.