80 
POPULAR SCIEIsrCE NEWS. 
[Jdne, 1891. 
AERIAL SPIDERS. 
Not content with living upon the earth, as their 
structure especially fits them to do, the family of 
spiders seeks also to conquer both the air and 
water. The peculiar aquatic spiders wliich spin 
their webs at the bottom of bodies of water have 
already been described in this paper, (December, 
1890) ; and in a recent number of La Nature we 
find an interesting description from the pen of 
Dr. H. de Vauigny, of the aerial, or balloon spi- 
ders, which, spinning their web in a tassel, or 
balloon of fibers, rise into the air, and are some- 
times wafted immense distances by the wind, 
much as the seeds of dandelions or thistles are 
scattered over the land l)y the feathery plumes 
with which they are provided. 
The studies of careful observers have shown the 
way in which these little balloons are made. The 
spider climbs to the top of a shrub or some other 
elevated position, to avoid collision with surround- 
ing objects, and spins a thread, which, as jt is 
formed, rises into the air, probably lifted up by 
the current of heated iiir ascending from the 
ground. After the first thread readies the length 
of a foot or two, the spider cuts it oflT, and, at- 
taching it to some neighboring object, proceeds to 
spin another. The process is repeated until .a 
shadow of a passing cloud, or the cutting off of 
the sun's rays by an artificial screen, causes the 
threads to droop and collapse. 
A remarkable ol)servation upon these spiders 
has been reported by M. Garry, of Valence, France, 
who states that he found one of them spinning her 
web into the form of two little hemispherical 
cups, or miniature hot-air balloons. They were 
connected together by separate threads, and the 
spider could pass freely from one to the other 
while en voyage. M. Garry believes that in this 
way the spider was able, in a small degree, to 
change the direction of her motion through the 
air, the same as with the gas balloons constructed 
by human beings, which can sometimes be steered 
in a course slightly varying from that of the pre- 
vailing wind. 
This remarkable instinct of the spiders, which 
causes them to make such extended aerial jour- 
neys, is undoubtedly of great advantage to them 
in the struggle for existence, and not only tends 
to spread the species over wide areas of country, 
but furnishes a quick and cfisy means of emigrat- 
ing in times of scarcity of food to new localities 
where food may be more plentiful and spiders less 
abundant. How the instinct of aerial emigration 
was first developed, or under what circumstances 
the first spider took her flight, is one of those 
mysteries which are beyond our present knowl- 
edge. The line dividing instinct from reason is a 
very indefinite one, and it is impossible to say 
where one ends and the other begins, or, in fact, 
to satisfactorily define at all the difference Im- 
tween the two manifestations of the animal intel- 
lect. It is not probable that the spider spins her 
threads and constructs her balloon by the opera- 
tion of the same mental processes that a man uses 
in constructing his larger aud more perfect aerial 
vehicles, but the exact way in which they differ is 
something that is left for future students of biol- 
ogy to discover. 
-«♦»- 
At the right, a spider spinning tlie threads to form the 
balloon. At the left, a spider with balloon completed and 
floating through the air. At the top, a tuft of threads left 
by a spider after the completion of the jonrney. 
sufficient number have been formed to give suffi- 
cient buoyancy to carry the spider on her pro- 
posed journey; when, gathering them together, 
she lets go, and is wafted by the currents of air 
for many miles. These flying spiders have been 
observed at a height of 2,000 feet, and it is be- 
lieved that their journeys often exceed one hun- 
dred miles. 
The cause of the buoyancy of these little spider- 
web balloons' is not thoroughly understood. Ap- 
parently the separate threads are charged with 
electricity as soon as formed, and thus repel each 
other, to form a light, bulky plume, instead of 
adhering together in a heavy mass. Their buoy- 
ancy is most probably due to the currents of 
heated air which surround them, and, in fact, the 
fibers themselves would become sufficiently heated 
by the sun's rays to warm the surrounding air 
and create an ascending current. It has been 
noticed that the spiders only take their aerial 
journeys on bright, sunnv davs. and that the 
[Original in POPULAR Science News.J 
FORMS OF BEAUTY — SUBMERSION FIG- 
URES. 
BY E. RATTENBURY HODGES. 
People widely differ with regard to theological 
and political forms, but all agree in their admira- 
tion of the shapes and hues which Nature gives. 
Even in a falling drop there is more of wonder 
and beauty than most persons imagine. When 
we for the first time see the phenomena referred 
to, Shakespeare's familiar lines, 
" Tliere are more things in heaven and earth 
Than are dreamt of in our philosopliy,** 
come to us with added emphasis. 
Let us make a brief study of a falling drop. If 
we fill a clear glass vessel with ordinary drinking 
water, and allow this to settle for about ten min- 
utes, then deliver to the surface or let fall from 
an inch or so above that surface, some colored 
fluid, — such as blue or, best of all, magenta ink, 
or a clear solution of cochineal, — we shall note 
that the drop not only descends, but as it sinks 
becomes flattened laterally, imd then changes into 
a beautiful rolling ring. Presently its downward 
course almost ceases; the ring then becomes 
somewhat vertically flattened and wavy in out- 
line ; the flner portions of coloring matter stream 
upwards, while the denser accumulate along the 
lower edge of the ring. In another moment this 
heavier matter is drawn to three or four points ; 
at each of these a fine tube .with a thickened, and 
at first trumpet-shaped mouth, is let down ; the 
thickened end of each tube then gets wavy like 
the original ring, and sends dpwn smaller stream- 
lO 
m(0, 
Mr 
ers, each of which displays ringed edges like the 
secondary rings. One might roughly compare 
these curious changes to an umbrella (without 
the stick) opening, and then from each of its 
points sending down a cord, out of the end of 
which grows another expanding umbrella, until 
we get a whole series of secondary and tertiary 
umbrellas, each set being smaller and more deli- 
cate than the preceding series. In some cases, 
however, the heavier portions of coloring matter 
collect at four, six, seven, or even eight points of 
the ring, bending it upwards in as many curved 
lines and letting drop as many rings, each of 
which becomes the seat ,of manufacture of two ; 
and in this polypus method of division and sul)- 
division the coloring matter gets diffused through- 
out the water or other fluid. 
So much for a general description of what takes 
place under the above conditions. It is now only 
necessary to remark before going further that 
very homely apparatus will suffice for the pro- 
duction of these "submersion figures," as Charles 
Tomlinson, F. R. S., their discoverer, has named 
them. A few tall and clear glass jars (such as 
some confectioners use), two or three glass tubes 
(eight or ten inches long, and drawn out at one 
end to a jet, with an opening about one-eighth of 
an inch in diameter), and various inks and oils; 
these are all the essentials for an ordinary experi- 
menter. 
There is a close analogy 
between the formation of 
smoke rings,or those formed 
sometimes in still air by a 
steam puff from a railroad 
engine, and these liquid pri- 
mary rings. (See Fig. 1.) 
In the case of a ring of 
smoke, the forces are pre- 
cisely the same, only gravity 
causes it to ascend and fric- 
tion hinders the ascent. 
" The ring of smoke or 
liquid acts as if rolling up 
or down the inside of a hol- 
low cone, and the direction 
of rotation of the particles 
will be found according to 
this view." In both cases 
the tendency of the ring in 
constantly to enlarge by 
difi'usion, and the rate at 
which it does enlarge is reg- 
ulated by the resistance of 
the air or liquid column. 
"" *\ 1 1 1 ^^ '^^ '"'''■y '"^ surmised, the re- 
V^wi^vJ^ sistance of the liquid col- 
umn is greater than that of 
an air column, and consequently liquid rings do 
not expand much, while those of vapor or smoke 
expand greatly. 
But to return to the " submersion figures." If 
a strong solution of common salt be colored and 
then passed through a paper filter, as it falls drop 
by drop into clear water which has well settled, a 
ring is formed whose outer surface is seen rollin;,' 
towards its inner vertical axis. While such rings 
are falling, sometimes one will overtake its prede- 
cessor, shoot through it, and then spread out 
beneath it without disturbing it. In Fig. 2, a, h, 
c, d, is illustoited the several stages of change 
which a drop of cochineal undergoes in falling 
through a dilute solution of silum water. A stron<r 
solution of permanganate of pot.ash (Condy's flu- 
id) yields some exceedingly fine figures. Some 
colored substances, especially the aniline dyes, 
serve well to illustrate these beautiful changes of 
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