[ 632 ] 
glafs, I then let go the feather which I before held, 
and its elafficity forces its two ends againft the lides 
of the glafs A , by which means the final! twig dl 
of the horfetail I have been fpeaking^of, and which 
was already fixed to the extremity of the feather fd , 
becomes alfo fixed ciofe to the fide of the glafs 5 the 
confequence of which is, that the ‘Polypus that is 
flicking to the horfetail is obliged to remain in fuch 
a fituation, as to be within the reach of a magnifier 
that is but of a ffior t focus. 
Nothing more is now wanting, but to place the 
magnifier before the objeft : for it would be both 
difficult and very inconvenient to hold it like a 
reading-glafs in the hand. In the inftrument k> i, h y 
g, e , I make ufe of, it is ferewed into a ring fixed to 
a fmall branch n,g, which has a ball ^ at its other 
extremity 5 this ball fits a focket, and fo makes a 
joynt, by which the firft branch is joyned to a fe- 
cond i, and that again in like manner to a third 
*, k , or fourth, if there is occafion. The foot of the 
whole is fitted near the edge, into a fmall board or 
tablet that holds the whole apparatus [Fig. 4.). By 
the means of thefe joynts, the magnifier e , may be 
rurned any way, and may be conveniently brought 
near to its ploper diftance from the objed, yet as 
the branch which holds it, cannot well be without 
feme fpring; it will be ftill difficult to adjuft the 
objeft exaftly to the focus of the magnifier when it 
is fhort, if only the magnifier was to be moved for 
that purpofe 5 and it will therefore be found eafier, 
when the magnifier is once right againft the objed, 
to move gently the glafs in which that is contained, 
till it is found to be precifely in the focus of the 
magnifier : 
