The late Learned and truly Valuable Dr. _Woodward_, to whom I first communicated my Intent, not only approv’d the Design, but also the Methods which, I told him, I design’d to pursue, to attain the desired Effects: and at the same time was so good to give me some useful Hints and Instructions, the better to accomplish an Affair, which he said ’twas his Opinion would be a general Good. Not to make this Acknowledgement of his kind Assistance, would be Ingratitude to my dear deceas’d Friend. As I had his Approbation at the beginning, had he but liv’d till now, I doubt not but the Discoveries I have made would have appear’d so considerable and useful, as might have entitled me to his farther Friendship and Assistance, in methodizing this Treatise for Publication. But depriv’d of him, my first and greatest Encourager, I have ventur’d to let it appear in the best Dress my Capacity will admit. Should the Stile and my Manner of handling the Subject to be treated of, appear uncouth and displease, I hope the Usefulness of it to the Publick will make some amends for that Defect. In treating on these Insects, some part of the Discourse may perhaps at first View appear surprizing, if not incredible to the Readers: But by giving them an account how I attain’d my Knowledge, and by often reiterated Experiments prov’d them to be certain Facts, they will soon alter their Opinion; and the whole, I hope, will not only be acceptable, diverting and instructive to the Readers, but also of universal Benefit to the Inhabitants in and about _London_ and _Westminster_. This Treatise being on a Subject as much wanted as any whatever, and the Pains and Trouble I have taken to arrive at my Knowledge herein, having been uncommon; it may be expected by the Curious, that I should give some of the Reasons that first induced me to undertake a Discovery so very difficult to appearance. It may not therefore be unnecessary to acquaint such, that in the Year 1726, my Affairs requiring my going to the _West-Indies_, I had not been long there arrived, before, (the Climate not agreeing with my Constitution) I fell sick, had a Complication of the Country Distempers, lost the Use of my Limbs, and was given over by the best Physicians at _Kingstown_ in _Jamaica_. But, contrary to their Expectation, recovering a little, they advis’d me to stay no longer in a Country, so prejudicial and dangerous to me, than till I could get Shipping for _England_; and in the mean time desired that as often as I was able, I would ride out for the Benefit of the Air; which as soon as I had Strength enough, I did. In one of my Journeys meeting with an uncommon Negro, the Hair or (rather) Wooll on his Head, Beard, and Breast being as white as Snow, I stopt my Horse to look on him; and he coming, as their way is, to beg a little Tobacco, I gave it, and enquir’d if he had been always so white-hair’d. He answer’d, no; but Age had made him so.