Now though this were the Instrument I made most use of, yet I have made several other Tryals with other kinds of Microscopes, which both for matter and form were very different from common spherical Glasses.  I have made a Microscope with one piece of Glass, both whose surfaces were plains.  I have made another only with a plano concave, without any kind of reflection, divers also by means of reflection.  I have made others of Waters, Gums, Resins, Salts, Arsenick, Oyls, and with divers other mixtures of watery and oyly Liquors.  And indeed the subject is capable of a great variety; but I find generally none more useful then that which is made with two Glasses, such as I have already describ’d.

What the things are I observ’d, the following descriptions will manifest; in brief, they were either exceeding small Bodies, or exceeding small Pores, or exceeding small Motions, some of each of which the Reader will find in the following Notes, and such, as I presume, (many of them at least) will be new, and perhaps not less strange:  Some specimen of each of which Heads the Reader will find in the subsequent delineations, and indeed of some more then I was willing there should be; which was occasioned by my first Intentions to print a much greater number then I have since found time to compleat.  Of such therefore as I had, I selected only some few of every Head, which for some particulars seem’d most observable, rejecting the rest as superfluous to the present Design.

What each of the delineated Subjects are, the following descriptions annext to each will inform, of which I shall here, only once for all, add, That in divers of them the Gravers have pretty well follow’d my directions and draughts; and that in making of them, I indeavoured (as far as I was able) first to discover the true appearance, and next to make a plain representation of it.  This I mention the rather, because of these kind of Objects there is much more difficulty to discover the true shape, then of those visible to the naked eye, the same Object seeming quite differing, in one position to the Light, from what it really is, and may be discover’d in another.  And therefore I never began to make any draught before by many examinations in several lights, and in several positions to those lights, I had discover’d the true form.  For it is exceeding difficult in some Objects, to distinguish between a prominency and a depression, between a shadow and a black stain, or a reflection and a whiteness in the colour.  Besides, the transparency of most Objects renders them yet much more difficult then if they were opacous.  The Eyes of a Fly in one kind of light appear almost