The following Sheets are therefore drawn up as an Explanation of these
Copper-Plates, and 'tis hoped they may even make them better understood
than they could be by the Doctor's own Accounts ; which must be ac-
knowledged (with all due Regard to the Memory of so great a Man) to
be frequently tedious and obscure, as well as so unmethodical, that to se-
veral Figures no Descriptions can possibly be found, but by turning over
the whole Book, there being no Direction at all to guide us to them.
It was necessary to form these Explanations from the Work itself where-
to the Plates belonged, but the Disposition, Stile, and Manner, will be
found entirely new : Whatever properly concerns the same Subject being
here brought together, from the different Places where scattered and in-
termixed throughout the MICROGRAPHIA, and expressed with the ut-
most Brevity and Plainness of Language.
This renders the present Volume so small : though it really contains the
whole Sense of all that is necessary fully to understand the following
Plates. And nearly one half, even of this Little, consists of new Dis-
coveries or Observations, made since the DOCTOR's Time, on the several
Subjects which the Figures represent : whereby a great Variety of Natural
History is conveyed to the READER's Hands, in a narrow Compass and
at a small Expence.—The Plates themselves will be found also more in-
structive, by engraving over every Figure an Account of what it is, and
of the Page where we may look for the Description of it.
Little more is requisite than to inform the Reader, that the Mi-
croscope Dr. HOOKE used was of the Double-Kind ; but much more
cumbersome, and less convenient, both as to its Structure and Apparatus
than what our Opticians make at present. For this Instrument (that new
Sort particularly which has very lately been constructed on an improved
Plan) is brought now to such a Degree of Perfection, that no Observer
need be apprehensive he shall be unable to discover, and that too very
easily, any of the minutest Parts of Objects which the Doctor could dis-
cern with the Microscope he employed.
The Doctor sometimes mentions the comparative Size of Objects when
magnisied by his Glasses ; and therefore, as the Curious may very naturally
enquire by what means he could compute their Bigness, it seems proper to
acquaint them with the Method whereby he took their Measure.—Having
(he tells us) rectified the Microscope, to see the desired Object through it
very distinctly ; at the same time that he look'd upon the Object through
the Glass with one Eye, he looked upon other Objects at the same Di-
stance with his other bare Eye : by which means he was able, by the Help
of a Ruler divided into Inches and small Parts, and laid on the Pedestal
of the Microscope, to cast, as it were, the magnified Appearance of the
Object upon the Ruler, and thereby exactly to measure the Diameter it
appears of through the Glass ; which being compared with the Diameter
it appears of to the naked Eye, will easily afford the Quantity of its being
magnisied.