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Hooke, Robert, 1635-1703 / Micrographia: or some physiological descriptions of minute bodies made by magnifying glasses : with observations and inquiries thereupon
(MDCLXVII [1667])

Observ. IV. Of fine waled silk, or taffety,   pp. 6-7


Page 6


                      MICROGRAPH IA,
       thofe of the silk are frallround, hard, tranJparent, and to theirbignefq
       proportionably Jiff, fo as each filament preflrves its proper Figgre,
and
       confequently its vivid refledion intire, though twifted into a thread,
if
       not too hard; thofe of Flax arejIat, limber,/ofter,and lefs tranifarent,
and
       in twitting into a thread they joyn,and lie o clofe together,as to
lofe their
       own, and defiroy each others particular refle~fions. There feems there-
       fore three Particulars very requifite to make the fo dreft Flax appear
Silk
       allo when fpun into threads. Firft, that the fubftance of it hould
be
       made nore clear and tranfparent, Flax retaining in it a kind of opacating
       brown, or yellow ; and the parts of the whiteft kind I have yet obfervd
       with the Micrafeope appearing white, like flaw'd Horn or Glafs, rather
       then clear, like clear Horn or Glafs. Next that, the filaments fhotld
each
       of them be rounded, if that could be donewhich yet is not fo very
necef-
       fary, if the firft be perform'd, and this third, which is, that each
of the
       finall filaments beJlifned3 for though they be fquare, or flat, provided
       they be tranifarent and ftiff, much the fame appearances muff neceffarily
       follow. Now, though I have not yet made trial, yet I doubt not, but
that
       both there proprieties may be afo induc'd upon the Flax,and' perhaps
too
       by one and the fame Expedient, which Come trials may quickly inform
any
       ingenious attempter of, who from the ufe and profit of fuch an Invention,
       may find fufficient argument to be prompted to fuch Inquiries. As
for
       the tenacity of the fubftance of Flax, out of which the thread is
made, it
       feems much inferiour to that of Silk, the one being a vegetable, the
       other an animal fiibftance. And whether it proceed firom the better
con-
       cootion, or the more homogeneous confritution of animal fiibfftances
       above thofe of vegetables, I do not here determine B yet fince I ge-
       nerally find, that vegetable fubflances do not equalize the tenacity
of ani-
       mal, nor thefe the tenacity of Come purified  i'neral li'b tancesi
I am
       very apt to think, that the tenacity of bodies does not proceed from
the
       hamons, orkooked particles, as the Epicureans, and Some modern Philofo-
       phers have imagin'd 5 but from the more exaft congritny of the confti-
       tuentparts, which are contiguous to each other, and lO bulky, as not
to
       be eafily Separated, or fbatter'd, by any fmall pulls or concuflion
of
       heat.
                  Obferv. I V. (ffine waledSilk, or Zajfrey.
Sehen, 3 .   His is the appearance of a piece of very fine Taffety-riband
in the
         Ad bigger magnifying Glafs, which you fee exhibits it like a very
con-
       venient f'ubfance to make Bed-matts,or Door-matts ofor to Cerve for
Bee-
       hives, Corn-fcuttlesChairs, or Corn-tubs,it being not unlike that
kind of
       work, wherewith in many parts in England, they make fuch Utenfils
of
       Straw,a little wreathed,and bound together with thongs of Brambles.
For
       in this Contexture, each little filament, fiber, or clew of the Silk-worm
       feem'd about the bignefs of an ordiriary Straw, as appears by the
little ir-
                                                                    regular


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