pound, 89; Culpeper’s, or three-pillar’d, ibid, improved
folar, 9 2 ; fcrew-barrel, or Wilfon’s Angle pocket, 103 ; fcrole
and mirror added to it, 10S; final! for opake objeCts, 107 ;
Ellis s aquatic, 110; anatomical o f Lyohet, 114; botanical
o f Dr. Withering, 1 15 ; common ditto, 1x6 ; and telefcope, a
portable one defcribed, 118; the necellary preparation fot
obfervation, 128.
Medium, what, 24 ; rare, and denfe, ibid.
Magnifying power of microfcopes, how to meafure, 54.
Magnifiers, botanical, 117.
Magny, Mr. his method o f meafuring the magnifying power o f
lenfes, 55.
Micrometer, the needle defcribed, 59.
Mufca chameleon, it’s changes defcribed, 220. •
Motion o f the wings of infeCts defcribed, 372.
Monoculus polyphemus, or king-crab, eyes of, 383; apus,
891-
Meloe monoceros defcribed, 390.
N [
Needle micrometer, 59.
O
Objects, opake, how examined in the lucernal microfcope, 73 ;
catalogue of, 688 ; tranfparent ditto, 76; catalogue of, 693;
mode of preparation, 134, 148.
Polypes, directions for finding, &c. 152; defcribed, 393; reproduction
of, 418.
Puceron, fee aphis.
Probofcis of a bee defcribed, 362 ; o f the tabanus, 704,
Pith confidered, 6 7 1 .
R
Ray8 of light, experiments mads with, 29; continued, 36, 37.
RefraCtion, experiments on, 35, 36-
Rind o f trees confidered, p. 6 5 4 -
S
Smith, Dr. his improvement on the compound microfeope, 18.
Solar microfcope defcribed, 19; improvements on do, 22; fplly
defcribed, 99; improved fo as to view opake as well as tranfparent
objeCts, 92 ; how to ufe it, 95.
Swammerdam, his mode of prep aring objeCts, 134, 138 .
Salts, how prepared, 163.
Silk worm, it’s changes and manner of fpinning, 211.
Skin o f the lump filh, 388; o f the foal,392.
Scales b f filh, 391; of the parrot filh, 392 ;jfea perch, 392:.
Haddock, 392 ; a perch from the Weft Indies, 392 ; foal, 392- v
Spider confidered, 700.
Seeds confidered, 692-
T
Torre, T. Di. of Naples, his mode of making and uling glafs,
globules, 10,
6
Termites,