Of  Examining  OBJECTS.
3.
it  be  a  living  Animal,  care  must  be  taken  to
squeeze,  hurt,  or  discompose  it  as  little  as
possible,  that  its  right  Form,  Posture,  and
Temper  may  be  discover'd.  If  a  Fluid,  and
too  thick,  it  muſt  be  thinned  with  Water:
if  too  thin,  we  ſhould  let  ſome  of  its  watery
Parts  evaporate.  Some  Substances  are  fittest
for  Observation  when  dry,  others  again  when
moistened;  some  when  fresh,  and  some  after
being  kept  a  while.
Light  is  the  next  Thing  to  be  taken  care
of,  for  on  this  the  Truth  of  all  our  Examination ¬
  depends;  and  a  very  little  Experience
will  ſhew,  how  different  Objects  appear  in
one  Position  and  Kind  of  it,  to  what  they
do  in  another.  So  that  we  ſhould  turn  them
every  Way,  and  view  them  in  every  Degree
of  Light,  from  Brightness  even  to  Obscurity;
and  in  all  Positions  to  each  Degree;  till  we
are  certain  of  their  true  Form,  and  that  we
are  not  deceived.  For,  as  Mr.  HOOKE
says,  in  many  Objects  it  is  very  difficult  to
distinguish  between  a  Prominency  and  a
Depression;  between  a  Shadow  and  a  black
Stain;  and  in  Colour,  between  a  Reflection
and  a  Whiteness.  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-ſhine,  like  a  Surface
covered  with  golden  Nails:  in  one  Position,
like  a  Surface  covered  with  Pyramids,  in
another