AS for the Report that doubt­less has reach'd your Ears, of the Loss of several of my Ma­nuscripts, and the Defacing of divers Others, 'tis but too true; and I am very sensible of it. But yet 'tis not barely upon my own Account that I am so, but very much upon that of my inquisitive Friends, and Mr. J. W. in particular. For I cannot but be trou­bled that I find my self disabled to an­swer the Expectations they had, that I should gratifie their Curiosity, by enter­taining them with several Tracts upon Philosophical Subjects: And that some unwelcom Accidents that have of late befallen me, oblige me to disswade them from expecting henceforward that I should present them with almost any Treatise, Finish'd and Entire. For ha­ving been for many years afflicted with a Weakness of Sight, that necessitated me, instead of Writing my Self, to Dictate to Others; and having been necessitated to make several Removes, some of them with too much haste to permit me to take an exact care of my Papers, or keep all of them together, and take them along with my self from place to place: When not long since I had occasion to review and range them, I found to my Surprize, as well as Trouble, that I want­ed four or five Centuries of Experiments of my Own, and other Matters of Fact, which from time to time I had commit­ted to Paper, as they were made and observ'd, and had been by way partly of a Diary, and partly of Adversaria, regi­ster'd and set down one Century after another, that I might have them in a rea­diness to be made use of in my design'd Treatises. And together with these Mat­ters of Fact, I found missing seven or eight Centuries of Notions, Remarks, Expli­cations and Illustrations of divers things in Philosophy, which I had committed to Writing as they chanc'd to occur to my Thoughts, and which might have place among the same Papers with the above-mention'd Experiments. How all these should come to be lost, whilst some o­ther Centuries of Notes and short Me­moirs, some of them Speculative and others Experimental, escap'd, I can as little declare, as recover them. But to add to the Misfortune (for such it is to Me, though perhaps not to the World,) One whom I had order'd to do some­thing with a Bottle of Oyl of Vitriol, un­luckily broke the Glass just over a flat Chest of Drawers, which I had pur­posely caus'd to be made for no other use, than to keep in it my own Manuscript Papers, whereof it had then good store. And though I happen'd to be at that time in the Room, and made hast to un­lock the distinct Drawers, and take them out; yet the highly corrosive Liquor had made such haste, and such havock, that several Manuscripts, and among them some that I most valu'd, were quite spoil'd, insomuch that there re­main'd not words enough undefac'd to declare what Subjects they concern'd; and that the other Manuscripts that mis­chievous Liquor had reach'd to, had some of them their Leaves half consum'd, and others a greater or lesser part of them; and all that the Menstruum touch'd, it made so rotten, that notwithstanding all our diligence, what was once wet­ted, could never be retriev'd.

'T was. Natural enough that this con­course of Mischances should suggest to me, that I was to take new Measures in reference to my design'd, but yet un­publish'd Writings. For first, it seem'd reasonable, that either I should wholly suppress some Discourses, wherein I had made a considerable progress, but had [Page 2]not finish'd them, or else should at least acknowledge and give notice, they are imcompleat, and blemish'd with divers Chasms, since a great many Particulars are lost, that should have done more than fill up those Vacancies: Which Defects I cannot now supply, many of the Ex­periments having been made, when I had by me some such Drugs and other Materials, and such Exact Instruments and Skilful Workmen as I am not now furnish'd with, nor am able to retrieve. Besides that, I was then also some times befriended by Opportunities and fa­vourable Circumstances, that I cannot hope for again.

To this first Reflection 'twas Natural to add another; which was; That since I could neither discover nor imagin how most of the Writings lately mention'd (with some others about differing Sub­jects) came to be lost; the surest course (if not the only sure one) that I could take to prevent the like Accidents for the suture, would be to publish from time to time; as fast as conveniently I could, those Remains and Fragments, as well as less mutilated Papers, that yet continued in my hands; premising to each distinct Bundle of them, an Ad­monition to those Readers that care for no Books that are not Methodical and Compleat, that they were not only free, but desir'd to pass these by, as Pieces both Confus'd and Unfinish'd.

I might add, that perhaps it may be more Prejudicial to the Author than to the Reader, that these Papers come forth with such disadvantageous Circum­stances: Since for the most part, the Me­thod of Writings that treat about Expe­rimental Philosophy, is not much min­ded and remembred by the Reader, at least after the first perusal; the No­tions and Experiments themselves, ab­stracting from the Order they were de­liver'd in, being the things that Philo­sophers use to take Notice of, and per­manently retain in their Memories. The Introductory Discourses and Prefaces to be met with among some of the very In­compleat Papers that accompany this Letter, may perhaps not be Unwelcom nor altogether Useless to some Ingenious Men; who will not be displeas'd to find themselves Excited, and perchance some­what Assisted, to take particular notice of some Subjects, that seem worthy of being more thorowly consider'd and cultivated than yet they have been. And some perchance may think the Designs I had upon such Subjects, not unfit to be pur­su'd by them in their own Way and Stile. And as for these heaps of Fragments, that seem to be more of a Chaotic Na­ture (if I may so speak;) Since the Par­ticulars they mainly consist of, are Mat­ters of Fact; their being huddled toge­ther without Method (though not al­ways without Order) may not hinder them from being fit, if well dispos'd of, to have places some where or other in the History of Nature; and to become not Unserviceable Materials in the Struc­ture that is aim'd at in this Age, of [...] and well Grounded Philosophy.