Together with my most hearty thanks for the favour you were pleased to do me, in sending me an _Epitome_ of what had been by the ingenious Monsieur _Auzout_ animadverted on a description, I had made of an _Engine_ for _grinding spherical Glasses_, I thought my self obliged, both for your satisfaction, and my own Vindication, to return you my present thoughts upon those Objections. The chief of which seems to be against the very _Proposition_ it self: For it appears, that the _Objector_ is somewhat unsatisfied, that I should propound a thing in _Theory_, without having first tried the _Practicableness_ of it. But first, I could wish that this worthy Person had rectified my mistakes, not by speculation, but by experiments. Next, I have this to answer, that (though I did not tell the _Reader_ so much, to the end that he might have the more freedom to examine and judg of the contrivance, yet) it was not meer _Theory_ I propounded, but somewhat of _History_ and _matter of Fact_: For, I had made trials, as many as my leisure would permit, not without some good success; but not having time and opportunity enough to prosecute them, I thought it would not be unacceptable to such, as enjoyed both, to have a description of a way altogether _New_, and _Geometrically_ true, and seemingly, not unpracticable, whereof they might make use, or not, as they should see reason. But nothing surprised me so much, as, that he is pleased (after he had declared it a fault, to write this _Theory_, without having reduced it to practice) to lay it, as he seems to do, in one place of his book, _p._ 22 upon the _Royal Society_. Truly, _Sir_, I should think my self most injurious to that _Noble Company_, had I not endeavoured, even in the beginning of my Book, to prevent such a misconstruction. And therefore I cannot but make this interpretation of what Monsieur _Auzout_ saith in this particular, that either he had not so {65} much of the Language wherein I have written, as to understand all what was said by me, or, that he had not read my _Dedication_ to the _Royal Society_, which if he had done, he would have found, how careful I was, that that _Illustrious Society_ should not be prejudiced by my _Errors_, that could be so little advantaged by my _Actions_. And indeed, for any man to look upon the matters published by their Order or Licence, as if they were _Their_ Sense, and had _Their_ Approbation, as _certain_ and _true_, 'tis extremely wide of their intentions, seeing they, in giving way to, or encouraging such publications, aim chiefly at this, that _ingenious conceptions_, and important _philosophical matter of Fact_ may be communicated to the learned and enquiring World, thereby to excite the minds of men to the examination and improvement thereof. But, to return; As to his _Objections_ against the _Matter_, I do find that they are no more against mine, than any other way of _Grinding Glasses_; nor is it more than I have taken notice of my self