I shall now for a moment draw your attention to that peculiar property of melted quartz that makes threads such as I have been describing a possibility.  A liquid cylinder, as Plateau has so beautifully shown, is an unstable form.  It can no more exist than can a pencil stand on its point.  It immediately breaks up into a series of spheres.  This is well illustrated in that very ancient experiment of shooting threads of resin electrically.  When the resin is hot, the liquid cylinders, which are projected in all directions, break up into spheres, as you see now upon the screen.  As the resin cools, they begin to develop tails; and when it is cool enough, i.e., sufficiently viscous, the tails thicken and the beads become less, and at last uniform threads are the result.  The series of photographs show this well.

[Illustration:  FIG. 8.]

[Illustration:  FIG. 9.]

There is a far more perfect illustration which we have only to go into the garden to find.  There we may see in abundance what is now upon the screen—­the webs of those beautiful geometrical spiders.  The radial threads are smooth like the one you saw a few minutes ago, but the threads that go round and round are beaded.  The spider draws these webs slowly, and at the same time pours upon them a liquid, and still further to obtain the effect of launching a liquid cylinder in space he, or rather she, pulls it out like the string of a bow, and lets it go with a jerk.  The liquid cylinder cannot exist, and the result is what you now see upon the screen (Fig. 8).  A more perfect illustration of the regular breaking up of a liquid cylinder it would be impossible to find.  The beads are, as Plateau showed they ought to be, alternately large and small, and their regularity is marvelous.  Sometimes two still smaller beads are developed, as may be seen in the second photograph, thus completely agreeing with the results of Plateau’s investigations.

I have heard it maintained that the spider goes round her web and places these beads there afterward.  But since a web with about 360,000 beads is completed in an hour—­that is at the rate of about 100 a second—­this does not seem likely.  That what I have said is true, is made more probable by the photograph of a beaded web that I have made myself by simply stroking a quartz fiber with a straw wetted with castor oil (Fig. 9); it is rather larger than a spider line; but I have made beaded threads, using a fine fiber, quite indistinguishable from a real spider web, and they have the further similarity that they are just as good for catching flies.

Now, going back to the melted quartz, it is evident that if it ever became perfectly liquid, it could not exist as a fiber for an instant.  It is the extreme viscosity of quartz, at the heat even of an electric arc, that makes these fibers possible.  The only difference between quartz in the oxyhydrogen jet and quartz in the arc is that in the first you make threads and in the second are blown bubbles.  I have in my hand some microscopic bubbles of quartz showing all the perfection of form and color that we are familiar with in the soap bubble.