Part IV. Natural PMofofhy. 
but alfo to keep the Flame of equal ftrength, for all fuch 
purpofes as require it. 
The MODEL of an EYE. In which the Humours arc 
reprefented by Gaffes of an anfwerable Figure. 
A BURNING-GLASS, about half a foot in Diametre. 
A HOLLOW BURNING-GLASS. That is to fay, two 
thin concave Gaffes fet together, and fo to be filTd up with 
water when it is us'd. About the fame bignefs as the 
former I but burnetii not altogether fo ftongly. Contrived 
and given by Dr. John Wilkinshxt Bifhop of Cbefter. 
A Large MICROSCOPE, with three Gaffes, and feve- 
ral Screws to fit it for all manner of pofitions. It magni- 
fies the Area of the Object to above a hundred times the ex- 
tent thereof to the bare Eye. 
A Leffer MICROSCOPE, fomewhat more managable 
than the former. 
The advantage of one with more Gaffes, is that it takes 
in a bigger Object, or a greater part of it. Of one with 
a fingle Glafs, that it lhews the Object clearer. So that to 
have a diftinct reprefentation of it, 'tis convenient to make 
ufe of both. Of the latter kind, I have feen feveral made 
by Mr. John Mailing in this City, not only with melted, 
but with Ground-Gaffes fo very fmall, that one of thefe 
Ground-Gaffes being weighed in the Ajj ay-Scales in the 
Tower, was found not above the fourfcorth part of a 
Grain. The Diametre or Chord »V h part, of an inch. 
Another, fo fmall, that thofe Scales were not nice enough 
to weigh it. The Chord hereof to that of the former, 
is as two to three. Thefe are the clearer! and belt that ever 
Ifaw. 
An OTOCOUSTICK,or Inflrument to help the hearing, 
made of Ivory. In fhape like a Funnel, faving that the Nofe 
is bended for the more convenient application to the Ear, 
and reception of the found. Given likewife by Bifhop 
Wilkins. 
Another of Copper, funnel cl at one end, as the former, 
and alfo belly cl in the middle. 
A Third of Tin, of a Conick. Figure, and with a Cochlea 
within it. The beft of all the three, is the firft. 
A Pair of HYDROSTATICK Scales. Ufed, amongft 
other purpofes,to examine the fpecifick Gravity of Bodies. 
