Consider the following experiment
You have two pieces of metal: copper and zinc
which you connect to conducting wires
and you then submerge the metals in an electrolyte
in this case vinegar
You will observe that bubbles will form
around the zinc but not on the copper.
The metal seemed dissimilar in this way
and if you then connect the two wires
holding the metals, something changes.
Tiny bubbles begin to form around the
copper terminal. It seems as though
something is being pulled from the zinc
through the wire allowing a reaction to
occur on the copper side and it turns
out this is a flow of electrical charge
as electrons are pulled away from the
zinc towards the copper through the
conductive path in the wire.
Think of this blow as the result of a
charge imbalance or electrical pressure
between the two metals as compared to
the instantaneous discharge observed
with static electricity experiments.
Towards the end of the 18th century
Alessandro Volta had been investigating
this effect. More importantly he found
that chaining these cells together
would amplify this flow of charge.
And by 1800
he simplified things even further
removing the jar which provided more
electrolyte than was actually needed.
He writes, "- A few dozen small round disks of
copper, [pieces of coin for example], and
equal number of plates of zinc.
- I prepare circular pieces of spongy matter capable of retaining water
- I continue coupling a plate of copper with one zinc and always
in the same order and interpose between
each of these couples a moistened disk.
This continues until I have a column as
high as possible without danger of it falling."
This is known famously as the
voltaic pile, the first battery in
history to provide a continuous flow of
electrical charge, or current. More cells
resulted in an increased electrical
pressure at the two ends and electrical
pressure was an early term for what we
now call voltage after Volta.
Now if the two leads of a voltaic pile were brought
into direct contact, a series of shocks
could be observed.
Now at first the utility of electric current as a
communication method was not immediately
obvious, aside from faint sparks and bubbles.
One idea was to use the presence
of bubbles to signal letters and the
Bubble Telegraph used this method though
it involved 26 different circuits, one
for each letter and it was based on the
fact that the battery providing the
current can be placed at a distance away
from the jars containing the leads
creating the bubbles.
An inventive although clumsy system
which was never adopted.
But very soon everything changed after a
famous demonstration in 1819. It was
found that if we simply pass a wire near
a compass and connected to a battery as
soon as the wire made contact with the
battery the needle jumped without any
physical contact. The only explanation
was that the current carrying wire was
creating a temporary magnetic field.
This was followed by a series of tasks to
figure out the direction of this field
first we assumed it was pointing along
the wire with the current or perhaps
emanating outwards from the wire as heat
would travel.
But eventually it was deduced that it must be traveling around
the wire in perpendicular circles, so a
loop of wire would create a magnetic
field which points through the center of
the loop and around the outside.
This lead to the galvanometer which was designed
to detect and measure electrical current
and it was just simply a coil of wire
with a compass suspended in the center.
Now when electric current was applied to the coil,
a magnetic field would push through the
middle of the coil and around the
outside so the needle would always point
perpendicular to the direction of the
force which was balanced on either side
of the needle, and the stronger the
current the stronger the deflection of
the needle.
And by 1824 William Sturgeon
demonstrated a way to increase the
strength of this field even more, simply
by wrapping a coil of wire around a
piece of iron such as a nail the
magnetic force could be amplified
because iron seemed to be a better
medium for supporting the formation of
magnetic fields. We call this
"permeability" and by wrapping the wire
many times the strength of the field
could be amplified thousands of times
and this is known as an "electromagnet".
So suddenly it was possible to create
magnetic fields which could move needles
with precision and force using electric
current applied at a distance using a
long loop of wire and a strong battery.
At the time our understanding of
information was in its infancy.
People were thinking about information and a
message as the number of letters in a
message so the goal was intuitive:
who could come up with the fastest way to
transmit letters and whoever had the
fastest system would therefore reduce
the cost per message for the sender
using this system.
And a gold mine was waiting for whoever
got there first.