he very steep angle
at which the bands run up the spectrum.

Into the theory of the development of these bands I am unable to
enter; that is a subject on which your professor of natural philosophy
is best able to speak. Perhaps I may venture to express the hope, as
the experimental investigation of this subject is now rendered
possible, that he may be induced to carry out a research for which he
is so eminently fitted.

Though this is a subject which is altogether beyond me, I have been
able to use the results in a practical way. When it is required to
place into an instrument a fiber of any particular size, all that has
to be done is to hold the frame of fibers toward a bright and distant
light, and look at them through a low-angled prism. The banded spectra
are then visible, and it is the work of a moment to pick out one with
the number of bands that has been found to be given by a fiber of the
desired size. A coarse fiber may have a dozen or more, while such
fibers as I find most useful have only two dark bands. Much finer ones
exist, showing the colors of the first order with one dark band; and
fibers so fine as to correspond to the white or even the gray of
Newton's scale are easily produced.

Passing now from the most scientific test of the uniformity of these
fibers, I shall next refer to one more homely. It is simply this: The
common garden spider, except when very young, cannot climb up one of
the same size as the web on which she displays such activity. She is
perfectly helpless, and slips down with a run. After vainly trying to
make any headway, she finally puts her hands (or feet) into her mouth
and then tries again, with no better success. I may mention that a
male of the same species is able to run up one of these with the
greatest ease, a feat which may perhaps save the lives of a few of
these unprotected creatures when quartz fibers are more common.

It is possible to make any quantity of very fine quartz fiber without
a bow and arrow at all, by simply drawing out a rod of quartz over and
over again in a strong oxyhydrogen jet. Then, if a stand of any sort
has been placed a few feet in front of the jet, it will be found
covered with a maze of thread, of which the photograph on the screen
represents a sample. This is hardly distinguishable from the web spun
by this magnificent spider in corners of greenhouses and such places.
By regulating the jet and the manipulation, anything from one of these
stra