by Dan Wiswell
I’m not sure when it occurred exactly, but sometime during the age of reason there used to be an educated group of people that were called philosophers. The term itself defined these individuals as “Lovers of Wisdom” and set them apart in a time before science focused the inquisitive mind of humanity. As science slowly began to replace alchemy and magic, scientific thought and reason replaced myth and superstition. Through this process the modern world evolved and philosophers were transformed into what we now call scientists.
As science morphed into a myriad of disciplines, our modern understanding of the universe began to take shape. That is not to say that the ancient world was devoid of invention and scientific discovery. We only need to look back at things like the Antikythera Device and other similar creations to dispel that notion. Warfare has always been a catalyst for invention. Siege engines used in military campaigns are where we get the word engineer, which is the term used to describe the people that manipulated, labored under and maintained those machines.
In the seventeen century the pace of technological advancement began to increase dramatically. The science of measurement was nurtured by the efforts of people like Galileo Galilei, Tycho Brahe and Antoni van Leeuwenhoek along with countless others, many of whom are now forgotten by time. They advanced the states-of-the-arts left to them by people like Nicolaus Copernicus and Leonardo da Vinci, to whom we are all now indebted. Isaac Newton furthered our understanding of optics in more ways than anyone else had ever been able to articulate, and he sparked the imaginations of countless individuals that ultimately led to the deployment of the Webb Telescope. Many had to suffer the consequences of being considered too forward looking, and for being out of step with contemporary theology.
The eighteenth century brought to science experimentations with naturally occurring electricity that gave us the first electrical components like the Leiden Jar, which we now call the capacitor. The development of electro-mechanical devices in the eighteenth and nineteenth centuries heralded an explosion of innovation. Alessandro Volta invented the modern battery in 1800. Andre-Marie Ampere, known as one of the founders of electrodynamics is credited as having invented the solenoid and the first electrical telegraph. Georg Ohm put all of those discoveries together, and in 1841 won the Royal Society’s Copley Medal for defining what we now call Ohm’s law.
The stage was set by these founding fathers for rapid advancements in our own field, the study of Metrology. About thirty years after Ohm’s signature achievement, Lord Kelvin created and then refined his galvanometer. This device was not only the first instrument of its kind to measure a quantity of electrical current, it also had the unique ability to show the absence of the flow of electrical current, as it was based upon an electrical meter movement that was zero-centered. This may not sound like an important innovation, but it allowed for the creation of electrical bridges in which a known quantity of electro-motive force could be measured against an unknown quantity. It could also be used to connect an unknown value in opposition to a known similar value to determine the unknown value of a broad variety of electrical parameters like resistance, capacitance, temperature and even such esoteric things as transformer turns ratios.
The introduction of Lord Kelvin’s galvanometer was followed shortly thereafter by the first mass-produced meter movement created and patented by Jacque-Arsene d’Arsonval and Marcel Duprez in 1882. This device utilized a coil of wire suspended in a magnetic field. It was set in place by an adjustable pivot-and-jewel assembly that was tensioned by hairsprings in such a fashion that a needle (or pointer) would track an arc that could be delineated by a hand-pointed scale. The entire assembly was balanced by copper weights or, in some instances, beeswax so that it would accurately provide indications regardless of the orientation of the movement. Many attributes of this technology had been developed more than a century prior to its emergence from methods employed by horologists as they perfected the art of manufacturing clocks and watches. It should be noted though, that just like many innovations, it takes the observations and dedication of one individual to change the course of human events. Mssr. Jacque-Arsene d’Arsonval will be remembered as such an individual.
In subsequent years the d’Arsonval movement was improved upon by Edward Weston when he patented his meter movement in 1888. It has always amazed me that two years before the invention of Weston’s meter movement the Edison Electric Illuminating Company of Boston was founded. In those days it must have been an exciting but dangerous time to be an electrical engineer.
The Weston meter movement became the mechanism of choice for nearly every manufacturer of electrical instruments in the United States in the late nineteenth and early twentieth centuries. Although other meter movement technologies existed in the following years such as iron-vane and electrostatic repulsion movements, to name a few, none were as widely used as the Weston movement. Suddenly, there was a technological explosion in the instrument industry that grew simultaneously with the newly created consumer appliance market. Instrument manufacturing companies employed thousands of workers in cities and towns all over the United States. A golden age of instrument design arose. Instrument manufacturers crafted products that were pleasing to both sides of the brain, expertly merging art with science. Elegant instruments began to appear. Manufacturers like Shallcross Manufacturing Company, Leeds and Northrup, and the Griebach Instrument Corporation began replacing the pointers on their meters with mirror-based meter movements that would optically project an image of a stylus that trans versed a meter scale. New instrument companies appeared all over the United States and the rest of the developing world. Dozens of panel meter manufacturers offered a variety of solutions to suit the needs and the ascetic tastes of their customer bases.
As is the case with many technologies, meter movement designs were not just improved by the needs of the market, but also by the advancements that are often caused by conflict. During the first and second world wars it became evident that critically important ship-board instruments were susceptible to damage caused by the concussion of ordinance and by the detonations of depth charges inflicted during submarine warfare. The engineered response however, took some time. It wasn’t until the end of the 1940s that advancements in materials research allowed for the creation of a new style of meter movement. New, ruggedized meters replaced pivot-and-jewel based movements that featured taut-band designs by utilizing high-strength alloys, which also negated the need for hairsprings in their assemblies. Taut bands in these newer meter movements suspended the moving coil with phosphor-bronze leave springs, which proved to be much more durable in harsh operating conditions.
As the twentieth century progressed, advancements in display technology began to chip away at the dominance of electro-mechanical instrument displays. The advent of digital circuitry also improved the accuracy and resolution of measurements significantly. An example of this is that prior to digital display technology, frequency measurements could not be expressed in any way nearing the ability of digital display resolution. But advances in technology always seem to move forward in fits and starts. The early Soviet space capsules featured an electro-mechanical display, with a representation of the Earth that rotated as it displayed to the cosmonauts the approximate location of where they were as they orbited above the Earth’s atmosphere.
In the western world, by the 1950s display manufacturers on the cutting edge of technology began competing with analog meter manufacturers by replacing them with digital meters sporting gas-plasma nixie tubes and other types of PCB-mounted, neon-based plasma displays with no moving parts. Edge-lit lucite blocks with etched numerical digits appeared briefly before being replaced entirely by LED displays. Instruments with Electro-florescent displays were designed for low light level environments. Early on, cat’s eye tubes, followed by oscillographic, and then picture tubes became features of mid-century front-panel design. Liquid Crystal Displays first appeared in 1968, which diminished the role of meter movements in display technology even further. It almost goes without saying that TFT displays are out-performing the devices imagined in science fiction of the 1960s. Over the past few decades, as computer screens have replaced many of the older display technologies, the internet has turned remote telemetry into a ubiquitous feature of the modern world.
As we stand back and see the ways that measurement technology has transformed society, we should all take a moment to marvel at the achievements brought forth by such humble beginnings. Because at a fundamental level, we have always created measuring devices so that we may extend our senses to perceive the phenomenon that surround us at the limits of our perception. And as we segue into the future, who knows? Maybe even King Tutankhamen himself was buried with an ancient Egyptian app for that.
Dan Wiswell is a self-described Philosopher of Metrology. He is President/CEO of Cal-Tek Company, Inc. and Amblyonix Industrial Instrument Company.
