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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. VI. Of small glass canes,   pp. 10-32

Page 10

  1o                   MICROGR AP HI A.
       mnanifeft to difcern the impreffions upon thefe wales, left by thofe
       were preft upon them,which lying not exafly parallel with them,but
a lit-
       tle athwart them, as is denoted by the lines ofo oo o,gh. Shrgh, between
       which the other wales did lie parallelbthey are fo varioufly,and irregular-
       ly creas'd that being put into that fhape when wetand kept fo till
they be
       drie, they fo fet each others threads, that the Moldings remain almoft
       long as the Stuff lafts.
          Hence it may appear to any one that attentively confiders the Figure,
       why the parts of the wale a, a, a, a, a, a, fhould appear bright;
and why
       the parts b, b, b, b, b, b, fhould appear fhadowed, or dark5 why fome,
       dd,d,d,dd, fhould appear partly lightnand partly dark: the varieties
       which refle&ions and fhadows are the only caufe of the appearance
of wa-
       tering in Silks, or any other kind of Stuffs.
          From the variety of refledion, may alfo be deduc'd the caufe why
       fmall breez or gale of wind ruffling the fiurface of a fmooth water,
       it appear black; as alfo,on the other fide, why the Smoothing or burnifh-
       ing the furface of whitened Silver makes it look black ; and multitudes
       other phenomena might hereby be folv'd, which are too many to be here
       infifted on.
                       Obferv. VI. Offmall Glafs Canes.
Scaem, 4- THat I might be fatisfi'd, whether it were not poffible to make
         TArtificial pore asfmalk as any Natural I had yet found, I made
       veral attemps with fmall glafis pipes, melted in the flame of a Lamp,
       then very Juddenly drawn out into a great length. And, by that means,
       without much difficulty. I was able to draw fome almoft as fmall as
       cobweb, which yet, with the Microfcope, I could plainly perceive to
       perforated, both by looking on the ends of it, and by looking on it
       the light; which was much the eafier waw to determine whether it were
       folid or perforated; for, taking a fmall pipe of glafs, and clofing
       end of it, then filling it halfufllofwater, and holding it againji
the light,
       I c-uld, by this means, very eafily find what was the diftering afpec
of a
       folid and a perforated piece of glafS; and fo eafily diffinguiffi,
       feeing either end, whether any Cylinder of glafs I look'd on, were
a Jolid
       flick, or a hollow cane. And by this means,1 could alfo prefently
judge of
       any fmall filament of glafs, whether it were hollow or not, which
       have been exceeding tedious to examine by looking on the end. And
       many fuch like ways I was fain to make ufe of, in the examining of
       vers other particulars related in this Book, which would have been
       eafie task to have determined meerly by the more common way ef look-
       ing on, or viewing the Obje&. For, if we confider firft, the veryfaint
       light wherewith the object is enlightened, whence many particles ap-
       pear opacous, which when more enlightned, appear very tranfparent,
       that I was fain to determine its tranfparenc) by one glafs, and its
       by another Next, the uwnmanageaLenefs of moft Oljecs, by reafon

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