No Words are Powerful Enough to Express the Importance of Basic Scientific Research.
by Jim & Rhoda Morris
9 Morningside Rd. Wakefield Ma. 01880    ---call 781 245 2897
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The Astatic Galvanometer and the Telescope
Two Scientific Instruments that Forever Changed the World

The two photo's on the left above are
Copy righted by   Istituto e Museo di Storia della Scienza
Click  Picture to make it larger

Click here to see Astatic galvanometers at work
in Edison's Menlo Park development laboratory where the light bulb was invented.

The Astatic  Galvanometer in the hands of a master inventor.

Thomas Edison'

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


This photo  shows you  what one of Galileo's telescopes looked like when it was new.  Click on photo  of our replica of Galileo's telescope to make it larger, click on that photo to make it even larger

Click here
to visit our page on making this  very fine and very precise telescope for Griffith Observatory.

IMSS in Florence Italy,  A museum that is a must visit for everyone.

No Words are Powerful Enough To Express The Importance Of Basic Scientific Research To Each Of Us And Our Future. We must fight for its rights!

Perhaps we should recognized, sponsor and establish a  yearly world celebration for the 12 most significant scientific instruments. one a month. It would be educational.
We suggest the first two candidates should be:

1, Galileo's   Telescopes Internationally famous, broadened our perspective by introducing us to the Universe.

2, Nobili's     Astatic Galvanometers; 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 etc.etc.etc.etc.etc.etc.etc.etc.etc.etc.etc.etc.etc.etc.etc.etc..

Both instruments deal with the flow of  fundamental particles; ( photons with telescope) (electrons with galvanometer) from a historical point of view they both are key examples of how  basic scientific research really works not our popular view, but the dull tedious work funding, marketing, and laboratory that goes into every discovery all of this is hidden from us because of the lack of suitable words (Remember No Words are Powerful Enough)

Galileo's telescopes, and early examples of  astatic galvanometers are on display at the  IMSS in Florence Italy  The telescope is out in front one of the first things one see's. The little astatic galvanometers that showed us how to have  finger tip control of enormous power is almost hidden in a darkish room off to one side. Hmmm?

Both these  instruments were made by Natural Philosophers who were interested in  searching out Natures  secrets. The technologist developing  these instruments started out with simple off the shelve materials  wood, glass, and wire to make their instruments. They used these primitive tools and their current knowledge  to design and build them. They used them to do basic research. and made significant fundamental discoveries, discoveries that made enormous differences in our everyday world, discoveries that  helped in improving the instruments (tools) which in turn  made more discoveries keeping the information loop growing to even more discoveries. How can we possibly ignore such an instrument or instruments and the scientist and technologist using them? What little we know about them has and can at times  been swamped by authors attention to the personal habits and eccentric behavior. The instruments and discoveries  total ignored or poorly described.

 Galileo's telescope which show us views of  the magnificent universe we live in gave us the first hint of the number of stars out there that we never could  have seen with the unaided eye. They gave us a poetic understanding of who we really were and are.

click here to visit our page on making this fine and very precise instrument for Adler Planetarium.

Nobili 's astatic galvanometers  like the telescope, which magnifies the effect of photons on our eyes,  magnifies  effects  of  electrons flowing  by the action of a  compass needle in a circuit. The astatic galvanometer is responsible for switching  on the technological world we live in. Like the telescope the astatic galvanometer gave us the view of the universe ,but in this case the micro universe, of the electrons so that we could benefit from this knowledge to harness the energy of electron  to our everyday needs.

The astatic galvanometers were the first instruments, after the discovery of the initial connection of electricity and magnetism, to give us quantitative and sensitive measurements to guide us through the micro universe of the electrons how to use them in new inventions and instruments  this in spite of the fact that we can't see them as we do with  photons.

Electrons  are the messengers connecting our  ears, eyes, nose, and sense of touch to our brains. They also do the  shuffling of the activities of the brain. They do the chemistry of the universe.  There are more electrons in our bodies than atoms and molecules, and  there are many more electrons in the universe then stars. With this endorsement why has there been such  little recognition of the instrument and the technologist that opened the door to the universe of the electron with the astatic galvanometer and  as Galileo opened the door of the astronomical  universe with his photon telescope?

Why has this very important instrument and its inventors  been  woefully neglected?
 Is it because there is apparently  little to no emotional people drama in the personal lives of the scientist who worked on and used them?. Are there no stories strong enough to write a book that would sell? Is it because electrons acts in a very anti social manner, always trying to get away from each other. Silly questions perhaps; however, wouldn't it be helpful to us if  we had a better grasp of story of the electron and its varied and busy life?

Don't they ever get tired? Isn't it sad that  electrons are not treated like the super stars that they are? What would happen if they went out on strike?

1, The rest of this this web site introduces us to Nobili astatic galvanometer
2, Click on the hyper link to get to our Galileo's telescope pages

It measures electric current  i.e. The number  of electrons passing through the instrument  per second.
There are close to 6.? x 1018 electrons every second going through a 100 watt light bulb.

A astatic galvanometer operates (similar to a telescope it magnifies)   it reads very small currents. It can easily measure one millionth of the electric current going through a 100 watt Edison light bulb operating on  direct current. (i.e. a microampere).  It can detect and measure the electric signal of the current generated in a muscle when it is being flexed. It measured the telegraph signal going thru the 2000 mile cable crossing the Atlantic.

What does an astatic galvanometer  look like?
The photos above show two views in their typical  form.

Etching is from a 1870  a natural philosophy text. the little needle on the platter rotates from zero as current passes through the instrument. The more current the more it moves..

This is a working example. We have instruments such as this in our collection some are for sale. Visit our home page. Click here for more details.


Astatic Galvanometer by Definitions & A Bit of History

The one word definitions from the American heritage Dictionary
adj. 1. Unsteady; unstable. 2. Physics. Having no particular directional characteristics. --astatically adv.astaticism n.

galvanometer  n. An instrument used to detect, measure, and determine the direction of small electric currents by means of mechanical effects produced by a coil in a magnetic field. --galvanometric  or galvanometrical ad --galvanometry n.

A short technical description
It is a  very sensitivity electric meter which was developed c 1825 out of work in basic research on electromagnetism where researchers were discovering  that an  electric current flowing in a wire generated a magnetic field that would make a compass needle move.  This type of meter is  a laboratory instrument that  can measure  very tiny electron current or voltage  with great accuracy.  Currents can be measured   in the millionths of an ampere range. This simple  instrument has been  coupled to a range of sensors that have given us most of the major discoveries in the physical sciences. They even ultimately helped to gather data in non electrical field of research and to make improvements in other current measuring instruments that helped in replaced astatic galvanometer  with even better current measuring instruments.

A few examples of the galvanometer and astatic galvanometer, concepts and uses.

A Demonstration Galvanometer (Tangent)

Above a very simple classroom Oersted demonstration galvanometer. showing the presence of a magnetic field generated by an electric current. A current source to be measured can be connected in three configurations, current can go  through  1st through ,bottom  2nd, top and 3rd, around  the coil. This is not a astatic galvanometer because it only has one needle. The unit is initially is set up so the needle and coil point in a north south direction. The needle interacts with the magnetic field of the earth and that generated perpendicularly by the current flowing through the coil.  The needle deflect as  the tangent of the of the angle of the needle to the north south line. It is  thus often called a tangent galvanometer. It also  gives the direction of current flow by the direction the needle moves, toward the east or west direction. This galvanometer has a  range in amperes. The  more turns the coil has the stronger  the magnetic field becomes for the same current thus increasing its current sensitivity of deflection of the needle. Some meters have coils with thousand of turns in the coil in an attempt to measure small currents. Unfortunately the electrical  resistance of the coil goes up and the current for a given voltage goes down. Also the needle always has the earth magnetic field to content with so there is a limit to the sensitivity it can achieve in this configuration. There are a number of ways of reducing these affect. The best solution was mounting another compass needle above or below the first but reversing it .i.e. north over south and south over north poles. Its called the astatic galvanometer.  The needle is usually suspended with a light thread of silk which gives the needle set a slight torsion to over come. More advanced  meters had a mirror attached to the needle. A collimated source of light  is brought onto the mirror and as it rotated with the current, the movement of the spot of light moves. The amount it moves depends on the distant the receiving scale is from the mirror. The further the distance of the scale from the mirror the more sensitivity the instrument is. It was not unusual for one of the authors to use spot distance upward 30 feet.  One disadvantage  was the magnets had considerable weight and therefore inertia   giving it the habit of oscillating back and forth like a pendulum. Some meters used a copper coil form others a copper sheet very close to the needles as a Faraday break to dampen the swinging. The movement of the needle and its magnetic field generated a current in the copper sheet. This current generated it own magnetic field that worked against the needle magnetic field reducing swing of  the movement. The movement was generally placed in a glass covered chamber to protect it from drafts. These instrument had high sensitivity and one their early jobs was  in the studies of  electrophysiology by their inventor.


Thousands and thousands electro mechanical gadgets bosomed forth from the astatic galvanometer  It was at the root of most of our early discoveries and inventions that we now take for granted. Below are just a few.
When two wire of different metals are joined together at one end and the junction heated it  generates a voltage that can be measured across the open end. It acts as a thermal battery. In the reverse sense if one route current thru this junction in the correct direction  it will cool the junction.
A demonstration apparatus that combines  a square box like coil with different  metals and a pair of magnetized needles forms an apparatus which is an astatic galvanometer for showing the thermal electric  Seebeck phenomena. The top of the box coil  is copper, the bottom  bismuth. At their junctions they form  thermocouples. Heating one  will generates a voltage difference between the dissimilar  metals causing a current to flow around the loop. This current  generates a magnetic field that acts on  the astatic apposing compass needles causing them to rotate, thus  indicating the heat generated a current flow in the box coil. the picture above shows one from these instruments which is in our collection.


Below note the astatic galvanometer is center stage of a typical laboratory set up  to measurement resistance of a special coil such as Dr. A. Bell's Telephone   ,   Dr. A. Bell's Metal Detector   and T Edison work  in electrical instruments including the Edison effect leading ultimately to the vacuum tube the late 1800's.


Note above; Physicist explored the fundamental laws of electromagnetic radiation spectrum using  astatic galvanometers wired up to the output current from a thermal pile, a radiation detector.  This system shown on the left was used to measure the radiation from emitting bodies like the light from a star, the radiation from a radio transmitter, a blackbody, a furnace, or even a Easter Lilly.

Another version of the operation of astatic galvanometer for the readers consideration and a bit of the development history by Instruments of Natural Philosophy "T.B. Greenslade Jr
Before the invention of the astatic galvanometer the existing galvanometers had a serious defects measureing small currents. Instrument such as the tangent galvanometer the galvanoscope and other simple galvanometers  the needle responded to the vector sum of the horizontal component of the magnetic field of the earth and the magnetic field produced by the current being measured. As long as the galvanometer is being used for qualitative measurements, it is important to turn the apparatus so that the compass needle points toward magnetic north when no current is applied to the coil.  Because the earths magnetic field is comparably strong only sizeable electric currents could be measured.

The development of the astatic magnetic needle by Leopoldo Nobili (1784-1835) in 1825 took the opposite path by eliminating the effect of the earth's magnetic field on the needle. A pair of needles is mounted parallel to each other, but with the poles reversed. This combination has a net magnetic dipole moment of zero and thus has no preferred direction in the earth's magnetic field. The lower of the magnetic needles is inside the coil which carries the current under test, and alone experiences a torque due to the resulting magnetic field.  .

Visit  Link 1 and  Link 2  At the IMSS in Florance Italy to see some of the earliest example of these instruments and a brief history of their development.


These instruments can be beautiful and playful.
Below one of our  astatic galvanometer we recently made as functional display piece. It measures  current in the  1/1000 ampere range.


Our replica of Galileo's beautiful Telescope The other important instrument in our lives.
Click  Picture to make it larger

Click here to visit our page on making this fine and very precise instrument at Griffith Observatory

 Below are close in shots of our Galvanometer.


The scale and the coils under the scale

Checking out the operator of the instrument

The input binding posts and the bottom of the coils

One of the leveling feet

The top of the suspension and zero adjustment

A scale for an astatic galvanometer


They come in a range of sizes. Below are some tangent galvanometers small, medium, and large.

One of our Tangent galvanometer 6" high

 One  of  our Helmholtz coil tangent galvanometer 14" high

They got pretty big... Below is a 12 foot high   Helmholz Galvanometer (astatic?)

The Largest Galvanometer in the World. Manufacturer and Builder, vol. 17, issue 11 (November 1885)

The engraving above while not a pocket electric meter nor a simple astatic galvanometer has the coil design of  a Helmholtz /tangent galvanometer.
 We have  included to show the diversity of jobs that galvanometers play and played in our advancement of  understanding how nature works. The operators are using telescope and mirrors instead of a moving beam of light as described above to read the current.  We've not been asked to build a replica of this instrument yet but we wouldn't mind giving it a try. it would be a great center piece for an museum on electrical measuring instruments..

THE IMSS  in Florence Italy has not only the exiting Galileo telescopes but also examples of Nobili instruments.
A must see on your visit to Europe.

No Words are Powerful Enough To Express The Importance Of Basic Scientific Research To Our Past, Present, And Future

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copyright 12/30/2006Jim & 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


Random notes to be expanded on

1-15-07- connections----------Photons and electrons can both treated as particles .  They both flow. The movement of electrons on the surface of a star  generates photons. some of which are collected by the objective lens of Galileo's telescope the photons are processed by the lenses and are directed into the observer's eye where they are converted back to electrons movement. This is   further processed electrically and sent  to  the brain where more electrons are  processed  into  an image which is further process with more electrons  into  an interpretation of what we see. This information is further process by even more electrons such as into the movement of our fingers jotting down  notes in a notebook. Electrons electrons, they are everywhere doing everything but they're not given credit for anything.

1-17-07 Neither Galileo nor Nobili invented their instruments,  Both instruments were amplifiers of a phenomena discovered by earlier work. Their instrument were used to make quantitative measurements of phenomena that could not be made with  unaided humans senses.  both made break through  improvements  in their  instruments which let us see and measure things that or forever changed our world!

1-18-07 junk stuff there are about 6 * 10^-9 grams of electrons per second  in 1 ampere???
or 6*10^-3 grams per second per micro-amps    or 6 milligrams of electrons????

Hydrogen is 1 gram per mole.
 there are 6.02 * 10^ 23 atoms per mole
 one electron is 1/1825 of the weight of a hydrogen atom
therefore  1 mole of electrons = 1/1825  of a gram =0.000547 grams or 0.547  milligrams
so 5.47 * 10^-4 grams/ 6.2 * 10^23 electrons per mole  = 0.88 * 10 ^-19 grams per electron

1 amp is a coulomb per second

1 coulomb is abt 6.24 10^18 electrons

??????????0.88 * 10^ -19 grams per electron  * 6 * 10^18 electrons per second  = 5.28 * 10^-1 I'm to tired to finish this and I'm going to bed