54 Of Examining Objects, 
it be a living Animal, Care mull; be taken to 
fqueeze, hurt, or difcompofe it as little as 
poffible, that its right Form, Poflure, and 
Temper may be difcovered. If a Fluid, and 
too thick, it mud be thinned with Water: 
if too thin, we fhould let fome of its watery 
Parts evaporate. Some Subftances are fitted 
for Obfervation when dry, others again when 
moidened ; fome when frefh, and fome after 
being kept a while. 
Light is the next thing to be taken care 
of, for on this the Truth of all our Examina¬ 
tion depends ; and a very little Experience 
will.. drew how different Objects appear in 
one Petition and Kind of it, to what they 
do in another. So that weihould turn them 
every Way, and view them in every Degree 
of Light, from Brightnefs even to Obfcurity, 
and in all Pofitions to each Degree; till we 
are certain of their true Form, and that we 
are not deceived. For, as Mr. Hooke 
fays, in many Objects it is very difficult to 
didinguifh between a Prominency and a 
Depreffion $ between a Shadow and a black 
Stain j and in Colour, between a Reflection 
and a Whitenefs. The Eye of a Fly, for 
Example, in one Kind of Light, appears like 
a Lattice drilled through with Abundance 
of Holes ; in the Sun-fhine, like a Surface 
covered with golden Nails : in one Pofition, 
like a Surface covered with Pyramids; in 
another* 
