Evening star., 1896-12-12

sortments Of machinery and manufactured
| goods for the South African market
Other ships VIII follow and the coming
year promises to be notable for the devel-
OF the globe. So active has this trade sud
denly become that New York shipping
houses are unable to charter enough yes
| seis to carry the cargoes consigned to
south African ports. and those that are
! cent are loaded to their fullest capacity.
Among those now on their way to South
AIrlca are several that have been regu-
larly employed in the South American
| trade. The only vessels that ply between
New York and South Africa are English
| beats operated by American agents of En-
siish companies. and they do not run reg
| ularly. The few American firms doing
business with South Africa have no yes.
sells of their own, but charter them as they
require them. but II the greater demand
IN south Africa for American goods con-
| tlnues and grows at the rate anticipated 1t
| may result In the establishing of one reg
ular American steamship line between New
York and South African ports.
Electric Current From the Air.
Over hundred years ago Benjamin
Franklin drew the lightning from the
clouds during a thunder storm, but 1t was
left to the present day and to Mr.. William
A. Eddy, the kite-fying expert, to prove
that an electric current can be drawn from
the atmosphere at any time and under
succeeded in converting this electric energy
into mechanical motion and he has also
been able to measure the relation between
humidity and electricity In the atmos-
phere.
Mr.. Eddy attracts the electricity, which
is, Of course. greatly diffused in the air, by
means of what he calls an electric collec-
tor This is simply piece of mosquito
netting, some three feet by five. mounted en-
light wooden frame. and covered with
tinfoil. The collector is attached to a kite
string, and by means of the kites is sus-
pended at any desired height. From 1t a
very light copper wire is hoped along the
Kite string to the ground. where it termi-
mates In an electric box. Mr.. Eddy uses The
principle OF attraction AMI repulsion in
taking off the electric spark. The box con-
tains magnet and a pair of rubber halls
covered with tinfoil, and pivotel so ;h.t
they can move backward and forward. The
electric current, collected in d-air, travels
down the copper wire to the electric box.
where the magnet draws It of In the form
of spark, and another wire, running into
the earth, grounds 1t.
1t did not take Mr.. Eddy long after begin
ming his experiments to find that he could
obtain an electric spark in this manner in
clear weather we'll as when clouds
charged with electricity were lowering
about. The only difference was that in q
dry atmosphere the collector had to be sent
to greater height before the lrst spark
was obtained. In cloudy weather and when
there was considerable humidity, the spark
Mashed off the wire when the collector wss
only !25 or $50 feet In the air, while in clear,
height of seven OF eight hundred feet to
obtain similar manipulation. This
satisfied Mr.. Eddy of two th. ngs: First, that
eiectrlcity Is present at all times, in con-
siderable quantities, though in a diffused
form, In the upper air; second, that hu-
midity acts as an absorbent or holder of
this electric force. By making numerous
observations and plotting the results he
a v,1an 6o
by the length of the electric spark The
result of this particular line Of experiments
has been embodied In a report prepared by
Mr.. Eddy for the weather bureau.
Some Interesting Facts.
Mr., Ed1y has discovered many interest
ing facts and some that are valuable as
well as interesting, by means Of his cleo
trical contrivance. One Is that he can de-
tect the approach of cloud by the inereas-
Ing length Of the spark, so that a blind
nan or man sitting in a closed observa-
tory could know of the approach of local
cloud. although he c3uld not see 1t. Anoth-
er fact that may make the electric col
lector an important assistant in the work
OF the weather bureau is that the gathering
OF storm, especially, of course an cleo
trical storm, can be made known to an OBJ
server by the increased electrical disturb
arces of the upper atmosphere before 1t
manifests itself in sny other way. A point
VI Suiio iou5 idtIiei tHdH pTdCUCda interest Is
the fact that the metal roofs Of our very
high buildings act electric collectors
This electricity is absorbed by the bricks or
carried off by the iron work beneath the
roof. SO that it seldom manifests itself
Given wooden building of sufficient
height, however. with a tin or meal roof,
and no gutter pipes or other conductors ex-
cept copper wire leading to the ground
and Mr. Eddy Is perfectly certain that he
can draw off electric sparks from that wire
at the eartf'S surface.
Perhaps the most interesting of all Mr.
Eddy's experiments in this peculiar field Is
that of converting the electric current
drawn from the upper air into mec lanical
motion. This has been done in a primitive
manner by Using light pasteboard wheel
set on pivot so as to revolve very easily.
A number OF small metal pins are set along
the rim of the wheel and the spark is at
tracted directly to these pins by the mag
net The resulting motion has been slight
as might be expected from sucn an ar
rangement and from the small size of the
collector. but it opens an attractive field for
experiment, and points to the line when
houses and small business establishments
may have their electric plants in the sky
instead of in the cellar, as is usually the
case at present.