The Astatic (Unstable) Galvanometer the most  important of all  electric scientific instruments
Visit our home web site and see a lots of historic instruments

 How they helped start and at same time discovered global warming  Photos of dozens of them in Edison's Menlo Park laboratory. With out them Edison wouldn't have invented the light bulb. 
by Jim & Rhoda Morris

Our dependence on electricity is why  the astatic galvanometer  was so important to our future.
The Astatic Galvanometer is an  unsung hero to all sciences.
It was a simple instrument that  could easily measurer a millionth of an ampere to hundreds of amperes of electron current. With the addition of a few resistors it could measure  resistance and voltage as well as current. It was   portable, easy, and inexpensive to make and operate. While not at work helping to make discoveries it was a wonderful tool to demonstrate and teach the principles of electricity,. something that it continued to do after its retirement from the research and development world. Following its history is important yet  neglected way of teaching how basic science, applied science, engineering, and business work together. It was the common instrument that was in the middle of all of it.

   Date last modified 11/26/2008


 Working together using science and engineering to build a bigger and  stronger economy.
They had one thing in common, not  often consider, They had a strong hand in starting yet findng Global Warming.

Thomas A. Edison
The Astatic  Galvanometer in the hands of the  master inventor.

Astatic  Galvanometer
Master translator extending the  humans sensory systems beyond what anyone could have imagined.

Henry Ford master manufacture.
  In 1929 Ford  Replicated  the Edison's original Menlo Park laboratory in Greenfield Village putting on display  many of the original instruments including the astatic galvanometers  for people to see and learn what science engineering and invention is all about.

The astatic galvanometer, from its birth  in the early 1820s ( via Nobili et al.) until its replacement in the early 1900's,  was  used in every major laboratory around  the world  by all of the  major experimental scientists, engineers, and inventors. It was responsible  for most of the major discoveries and inventions of physics  that were to impact all the other sciences.  It did most of its work during  the 19th century. Everywhere around us we see products of its use and use  these constantly. Does familiarity breed complacency ?

How can it be that we  know so little about the astatic galvanometer?  Was it because it was just a tool? , Maybe,  but so were telescopes and microscopes, and everyone knows about them? 

This web page hopes to shine some light" (No pun intended) on  a flock of them working silently away in  Thomas Edison Menlo Park Lab
where the modern age of  electrical devices for home, work and play were being  geared up for the future. They are there ,clearly visible, demonstrating that Edison knew their value, but why don't we? Electrons are a big thing in our lives especially today and getting bigger all the time.

Click here  for the technical details of  how they work. See the stages of development and an example of a large beautiful working presentation astatic galvanometer.   Or read on for evidence of their importance.  See them spread around Edison's laboratory and what they did for Edison in the development of the light bulb and its accessories.

What follows on this website is  practical example of some of  the roles  the astatic galvanometer, along with its brothers and sisters,  the tangent galvanometer and the Helmholtz Galvanometer,  did in bringing  new  technology  to the public. They  made it possible for Edison and his staff, to measure all the critical data needed to invent and develop the light bulb and its accessories. If one studies the pictures of Edison's laboratory at Menlo  closely one see's them  everywhere but noticed by no one.
In the Edison example they measured the light  bulb's
power inputs 
light outputs,
output of the electric current  of the electric generators to power them
The nature of wire to conduct current of electrons to and from the bulb the fuses, switches, connectors
In amongst this capacious activity  they even found what is called the  Edison effect (electrons being emitted by the light bulb's hot filament)  which  was   the heart of the radio tube industry.

Many other devices and discoveries, just as in the light bulb, were discovered,   measured,  and developed   by these unique little desk top electron counters.

We start off on our tour of Edison laboratory where the light bulb and many other inventions were born.  The photo below  which is a mug shot of two  little astatic galvanometers standing at attention like solders in their own small box on the ground floor of Edison's laboratory.  Literally and physically they were in the center of the business of science and engineering part of the laboratory,  atop  brick pillars.  quietly doing their job of counting electrons (current) for the master of  electricians Thomas Edison.

Below is a small sampling of the distribution of the astatic galvanometers through Edison's labs

The plaque displayed in front of one more sensitive astatic galvanometer in the replication of Edison's Menlo Park development laboratory where the light bulb and many other electrical products were created.

Thomas Edison's first light bulb used to demonstrate his invention at Menlo Park.

On the bench in Menlo a Astatic  Galvanometer surrounded by its team (gang) of accessories ready to be pressed into service.


Note the brick pillars that hold the box of this set of astatic galvanometers

Looking through the window in the side of a  box, which sits on  brick pillar, into  its interior showing  a  light beam astatic galvanometer and its light scale.

Another view  of the box showing the back of the light scale and a set of batteries.
The astatic and tangent galvanometers such as in the photo  at the right made the telegraph, the Atlantic cable  and the telephone possible just as it did for the light bulb.

Astatic in the front and a tangent galvanometer in the back ground .

Scales, batteries, transducers, resistance boxes, and other associated accessories surrounding the galvanometers.

Here is one housed in a brass cylinder next to a battery and large Helmholtz set of coils.

A Helmholtz Galvanometer


Here is a light spot scale for one  mounted on a ring stand which is next to shelves of chemicals
Jim is  sitting at  Edison's telegraph desk  which was located in the Menlo Park laboratory from which Edison  announced many of his inventions

.Jim (one authors) felt very much at home in Edison's Menlo Park lab and telegraph station having built, repaired, and  used many of the types of instruments found there---  but also  like Edison Jim also worked  as a telegrapher

Again even more Uniquely! almost like a Ripley believe it or not story.

Jim like Edison also worked as  a  light bulb engineer and inventor.

In between these two jobs Jim worked as a basic research physicist  studying the light emitting processes of plasma and solids.

Unlike Edison however Jim is  now working as an independent scholar of  early scientific instruments.

It looks like Mr Edison  is asking the question

 "Who is that on my right sitting at my desk of my telegraph station? I hope he doesn't take any  of my astatic galvanometers home with him"

 Here are two more  Astatic Galvanometers and pieces of a prism spectrometer with bits and pieces of equipment needed to enter the new world of electric power. They seemed to be on every bench in every cabinet of the facility. Click here to see what the original spectroscope look like in its prime.

Our dependence on electricity is why  the astatic galvanometer  was so important to our future.

We may not know or don't think about it but  it is electrons that are among the principal ingredients  that everything in the universe is made of. Electrons  their electro chemical, mechanical, and magnetic forces soaks into everything, even into every atom and molecule making up our body. Because of this the astatic galvanometer (a sensitive  electron flow meter counting the number of electron going through it) made it possible to  search into how  the electric part of nature works  at its most fundamental level. It is electrons that give us the light  that telescope,  microscope, and the spectroscope see and amplify and analyze.
  • For nearly 80 years

  •  It gave  humans for  the first time a quantitative way of monitoring and make  measurements of  most all things in nature doing their electric thing.

  •  It was the translator of electric signals in nature   into  the movement of a needle across a scale of numbers

  • In its youth it was used  first by scientist in the medical profession to study the generation electricity signals in our bodies.

  • It was instrumental is studying the  generation of electricity through the  interaction of  atoms and molecules with each other( batteries etc.).

  • in the generation of electricity  from light (the photocell)

  • and light from electricity (the electric arc and incandescent bulb)

  • The ejection of electrons from hot objects (The Edison affect)

  • the generation of electricity from heat (the thermocouple)

  • it was used to discover new  things that could be used to design a better instrument to replace its self.

on an on.

This paragraph  show one   a typical example of how and what astatic galvanometers did  that so changed our world.
Lets start by taking  just one of our senses and show how the a g expanded it.  Sight is one of the easiest and most important of our senses.  We humans  can only sense a very tiny  part of the electromagnetic  radiation spectrum with our eyes, we call it the visible spectrum . Before the advent of the astatic galvanometer we did not know,  that there  were radiations from super short waves, cosmic rays, all the way to super long and longer radio waves. Shortly after the astatic galvanometer( a very sensitivity current flow meter) was invented humans began to find out that there were all sorts of materials in nature that  when hit by these  rays would  produce  a shift or flow of electrons in that material. This electric current  could  be  measured by this little inexpensive instrument  and could and was correlated to the strength of these rays. This  essentially expanding sight (our view though just the  visible spectrum) to the whole spectrum of our world enormously.  The same phenomena was found to be true for all the rest of our senses. touch smell sound etc. Suddenly  the size of our world expanded dramatically. This little instrument's discoveries fostered other instrument other detectors. Some of the discoveries were turned into much faster communications,   the telephone the telegraph  the radio, which fostered more discoveries faster etc etc   all from the connection of these little astatic galvanometer to the hidden world of electrons.

So why if  the astatic galvanometer is so important that we  haven't  heard more about these little instruments  and their stories? 
One possible reason may be that there was no personal drama in its development. No one person stood out  as a danger to society, the church, the government. No hook of personal excitement and drama to make a popular an interesting story that the public would read.  So like most good science it just churns  along giving a piece by piece  understanding of how nature works. To say it in more familiar terms , one small  discovery breeds another and another until we have a better understand of the whole. This is the where, and how, of the little astatic galvanometer's role in science and industry.

The bottom line. It did its work and thus deserves some lime light for its contribution to mans progress to a better life. Its a symbol just  like Galileo's telescope but no where as much appreciated. There should be one in every school  and museum reminding us of how very clever humans can be  given a little piece of copper wire, some string. a few iron needles, and some wood to hold the lot together.

The astatic galvanometer helped  start  Global warming!  But also helped flag a  warning of it happening.
Last but not least.
Connect one  to a pair of iron / copper thermocouples  each  stuck into a bit of wood. Put one of the pieces of wood in the shade, the other in the sun light where  it warms  up.  A voltage will appear across the thermocouples which can used to measurer ,quantitatively, the infrared radiation ( that  humans can't see)  from the sun reaching your detector. The  first step in a chain of events of forecasting the prospect of global warmingWarning us before it is too late of the catastrophic consequences such event could  cause the human race. Remember all those electric power stations that Edison helped to invent spewing out  all that CO2. Like most  information that science  produces it serves as a double edge sword.

A beautiful working presentation piece
It gave us our first meaningful connection to the  micro universe of the electron. completely revolutionizing our finger tip control of great power: tapping  the energy of the atom,  communicate around the world and to the planets,  looking into our genes putting our  telescopes on other planets.

The authors thank the staff of the replication of the Menlo Park laboratory  for their generous time  and patients with us  while we took the pictures you see on this site. Thank you much.

copyright 7/30/2007Jim & Rhoda Morris

All photos and written material are by Jim & Rhoda Morris unless noted otherwise. Free personal and educational use and reproduction is encouraged; all commercial rights are reserved

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