[ 6 33 ] 
magnifier : and for this purpofe the fmall board up- 
on which the giafs is placed, ought to be well 
fmoothed. 
The light that comes in at a common window 
will be found fufficient, for obferving in the water 
fuch obje&s as are to be feen with the bare eye, or 
with a hand magnifying giafs $ but fuch as muft be 
examin’d with a lens of a fhorter focus > muft be 
view’d by the light of a taper, placed beyond the 
giafs, and whofe flame is fo order’d as to be upon 
the level with the objedl. 
A magnifier thus once adjufted may remain in the 
fame place before the objeft, for feveral days toge- 
ther, without being diforder’d 5 fo that, to obferve?- 
the progrefs of the infeft during all that interval * 
no more will be necefiary, than to place from time 
to time a taper behind the giafs, and to apply the 
eye to the already fixed magnifier. 
Several of thefe apparatus s may be placed upon 
one and the fame board by one another 5 and thus 
at the fame time obfervations may be made and 
carried on upon different forts of infeds, or upon 
feveral infefts of the fame fpecies ; in order to come 
fooner and with more certainty at the knowledge 
of the faffs one is enquiring about. 
could never have difeovered the manner in 
which the cluftering ‘Polypi are multiplied, but by 
the help of the expedient I have juft deferibed : and 
before I had the ufe of that apparatus , I only knew 
in general the figures of thole Polypi , and of the 
clufters that contained them. I had taken notice 
that thofe clufters grew, and I had reafon to fufpeft, 
that a whole clufter came from a Angle Polypus + 
Nnnn 2 but 
