[ 631 ] 
felves been taken; and I fhift this water more or 
lefs often as the circumftances may require. 
It is eafy to conceive, that to obferve a fmall in- 
fedt in one of thefe glaffes, with a magnifier of a 
fhort focus , it is neceffary that infeS fhould be 
placed very near to one of the fides of the glafs ; 
and that it ought alfo to be kept fteadily in the fame 
place. The infed ought therefore to be either fixed 
to the fide of the glafs itfelf, or to fome other body 
that may be conveniently fo fixed. I chafe, for this 
purpofe, fubftances that are flender and fupple, fuch for 
example as the fmall branches or twigs of divers fpe~ 
cies of the Equifetum paluflre , or water horfetaih 
The cluttering ‘Polypi are often found upon thefe 
twigs, and they may be made to fettle upon them 
from elfewhere, as I {hall take notice, by and by. 
Now this is the way I take, to fix one of thefe 
twigs of horfetail againft the fide of my glafs. 
Having chofen a fmall flip, upon which there is one 
or more of the cluttering Polypi or the like, I take 
a piece of a peacock's feather, longer or fhorter, 
according to the diameter of the glafs I am then to 
ufe. From this piece of peacock’s feather I cut away 
all the lateral branches or beards on both fides, ex- 
cepting one at one of its extremitys / upon this one 
I make a knot near its infertion, but do not at firft 
draw it clofe. I then bring this open knot to the 
fmall flip of the horfetail that is floating in the wa- 
ter of the glafs, and I get one of its extremities into 
the knot, which I then draw clofe ; and the flip of the 
horfetail is thus joyned to the piece of the feather. 
I next take hold of the feather, and bending it near the 
middle, I force its two ends (Tab. I. Fig . 4 )b,f, into the 
N n n n " glafs 
