Watertown republican. [volume] (Watertown, Wis.) 1860-1906, 1860-08-10
HOW a FLY HOLDS ON.

I have here incIosed a small window-fy
in the live box of a microscope, that you
may examine the structure of it's feet as
it presses them against the glass cover;
and thus not only get a glimpse of an ex-
quisitely formed structure, but acquire
some correct ideas on the question of how
fly is able to defy all the laws of physics,
and to walk jauntily about on the under
surface ofpolished bodies, such as glass,
without falling Or apparently the fear of
falling. And personal examination is the
more desirable because of the hasty and
erroneous notions that have been promul-
gated on the matter and that are constant
ly disseminated by herd of popular COM
pliers, who profess to teach science by gath
ering up and retailing the opinions of 9th
ers, often with the slightest knowledge
whether what they are reporting is true or
false.
The customary explanation has been that
given by Derham in his "Physico-theolo-
gy:" that &c divers flies and other insects,
besides their sharp hooked nails have also
skinny palms to their feet, to enable them
to stick to glass and other smooth bodies
by means Of the pressure of atmosphere,
after the manner as l have seen boys carry
heavy stones, with only wet piece of
leather slapped on top ofa stone. % Bingely
citing this opinion, adds that they are able
easily to overcome the pressure of the air '' in
warm weather when they are brisk and
alert; but towards the end of the year, this
resistance becomes too mighty for their di-
minished strength; and we see flies laboring
along and Juggling their feet on windows as
if they stuck fast to the glass; and it is
with the utmost difficulty they can draw
one foot after another, and disengage their
hollow cups from the slippery surface.
But long ago another solution was propos-
ed for Hooke, one of the earliest micro
scopic observers, described the two palms,
patterns, or soles Gas he calls the pulvilla)
as "beset beneath with small bristles or
tenters, like the wire teeth of card for
working wool, which, having contrary
direction to the claws, and both pulling
different ways, if there be any irregularity
or yielding in the surface of body, ena-
BILE the fly to suspend itself very firmly"
He supposed that the most perfectly polish
ed glass presented such irregularities, and
that it was moreover always covered with
a 'ssmoky tarnish," into which the hairs
of the foot penetrated
The s'smoky tarnish'' is altogether gra-
tuitous, and Mr.. Blackwell has exploded
the idea of atmospheric pressure, for he
found that flies could walk up the interior
of an exhausted air pump. He had ex-
planned their ability to climb up vertical
polished bodies by the mechanical action
Of the minute hairs of the interior surface
of the palms; but further experiments hav-
ing showed him that flies cannot walk up
glass which is made moist by breathing on
it, or which is thinly coated with oil or
-four, he was led to the conclusion that
these hairs are in fact tabular, and excrete
viscid fluid, by means of which they ad-
here to dry polished surfaces and on
close inspection with an adequate magnify
ing power, he was always able to discover
traces of this adhesive material on the
track on glass both of flies and various
other insects furnished with pulvilla, and
of those of spiders which possess similar
faculty.-Gosse's Evenings at the Microscope.
CAUSE OF METEoRs. Bartlett
theory for the explanation of this phenom-
ena is as follows: "These bodies are Of
the nature of planets, and circulate about
the sun in orbits as unerringly as their
larger brethren. When they and earth
come simultaneously to those points Of
their orbits which are nearest together,
the action of the earth often becomes SUI
perior to the sun, and the small masses are
drawn to its surface. Plunging with enor-
nous velocity into our atmosphere, these
little bodies compress the air in front and
rub against it with such violence on the
sides, as to produce heat enough to fuse,
and light sufficient to illuminate the most
refractory and darkest of substances
The exterior and molten crust is swept to
the rear by the resisting air; new sur
face becomes exposed; this, in its turn,
is fused and carried backward, and so on,
till finally the whole track of the meteor
is strewn with groups of disintegated and
scintillating material"
The Michigan Farmer estimates the
wheat crop of that State this year to be