inconveniences, I made but little use of. My way for fixing both the Glass and Object to the Pedestal most conveniently was thus: Upon one side of a round Pedestal AB, in the sixth Figure of the first _Scheme_, was fixt a small Pillar CC, on this was fitted a small Iron Arm D, which could be mov’d up and down, and fixt in any part of the Pillar, by means of a small Screw E; on the end of this Arm was a small Ball fitted into a kind of socket F, made in the side of the Brass Ring G, through which the small end of the Tube was screw’d; by means of which contrivance I could place and fix the Tube in what posture I desir’d (which for many Observations was exceeding necessary) and adjusten it most exactly to any Object. For placing the Object, I made this contrivance; upon the end of a small brass Link or Staple HH, I so fastned a round Plate II, that it might be turn’d round upon its Center K, and going pretty stiff, would stand fixt in any posture it was set; on the side of this was fixt a small Pillar P, about three quarters of an inch high, and through the top of this was thrust a small Iron pin M, whose top just stood over the Center of the Plate; on this top I fixt a small Object, and by means of these contrivances I was able to turn it into all kind of positions, both to my Eye and the Light; for by moving round the small Plate on its center, could move it one way, and by turning the Pin M, I could move it another way, and this without stirring the Glass at all, or at least but very little; the Plate likewise I could move to and fro to any part of the Pedestal (which in many cases was very convenient) and fix it also in any Position, by means of a Nut N, which was screw’d on upon the lower part of the Pillar CC. All the other Contrivances are obvious enough from the draught, and will need no description. 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.