Wednesday, October 13, 2010

The Self-taught Master, part 1

Poor is the pupil who does not surpass his master. 
— Leonardo da Vinci

Much of Franklin’s self-education came from his own observations of the natural world and of his fellow man, but can’t be found in the Autobiography: even he refers us elsewhere for an explanation of his electrical experiments, and he is coy (but not silent) about his influence on others. For a better sense of his powers of discernment--scientific and otherwise--I have relied on Carl Van Doren’s excellent biography; Benjamin Franklin (1938), and the second volume of Isaac Asimov’s three-part Understanding Physics (1966). Today’s post is focused on the scientific.

The first fifty pages of Van Doren’s book are essentially the Autobiography with a few gaps filled in and added historical perspective. As it progresses the contextual infill is expanded, until 1757 when the Autobiography breaks off. The remaining two-thirds are based on Franklin’s other writings and the author’s own research.

Asimov’s book includes a technical explanation of Franklin’s experiments with electrostatics. His most famous demonstrated the equivalence of lightning to electricity, which seems obvious to us but was unproven for the scientists of the time (while for the common people, lightning still had an almost mythological aura). The famous story of the kite and the key is factual, but came after his conjectures had been proven.

The then-prevailing notion was that electricity came in two forms: “resinous” and “vitreous.” Charged resins would repel each other but attract charged glass tubes and vice-versa. Franklin’s insight was that there are not two but only one “electrical fluid,” and that the attractive or repellant forces are a result of a lack or surfeit of the fluid: a “negative” or “positive charge.”

According to Van Doren, Franklin coined terms common to us today:  armature, battery, brush, charge, charging, uncharged, condense, conductor, non-conductor, non-conducting, discharge, electrical fire, electrical shock, electrician, electrified, minus/negative, and plus/positive (BF.173). These last, said Franklin, like magnetic north and south are two aspects of the same thing. All objects have electricity, he said, but “uncharged” bodies are at equilibrium. Thus electrical charge can be neither lost nor destroyed, only in or out of equilibrium. When “grounding” static electricity, any excess electric fluid returns to the body of the earth, where it is so broadly distributed its presence can no longer be felt.

Because electrical charges can exist in isolation (unlike the poles of a magnet) and there is no general reference (as the earth’s magnetic field is for the compass), Franklin had no way to know which charged body held the excess electric fluid (for him, the “positive” charge), and which lacked the fluid (the “negative”)--so he was forced to guess. His odds were even, but he guessed wrong. Years later, once the electron was understood, it was determined that “positively” charged bodies in fact lack electrons; for this reason electrons--the movable electric fluid--are assigned a negative charge. (UP2.163)

Franklin also found that a spark moves through air more easily, and more quietly, towards a pointed object than towards a blunt one. Once lightning was shown to be electricity, the lightning rod became obvious. This simple device was adopted across the western world and within two decades removed this ancient danger to lives and property and earned applause from commoners and kings alike. Asimov suggests Franklin’s fame was particularly useful a quarter century later, when he was made ambassador to France of the newly independent United States, then fighting for its existence. (UP2.175)

Franklin held wide-ranging interests and an unremitting creative mind. He corresponded with experts in economics, biology, medicine, physics, geology, physiology, meteorology, and agriculture (he briefly owned a farm). Van Doren highlights a few:
  • He noted the different onset times of a major storm across the colonies and conceived of a macro weather pattern, dubbed the jet stream nearly two centuries later.
Appalachian Orogeny
  • He noted the marine fossils found at the highest peaks of the Appalachian mountains, and guessed that the world must be extraordinarily old. Franklin had no way to know it, but the reason for this oddity is found in the geology of plate tectonics.
  • Against Newton’s then-prevailing theory, he decided that light must be a wave and therefore must travel through a medium. It took Einstein to eliminate the theoretical need for an “aether” 150 years later.
  • He created the first flexible catheter in the Americas.
(all: BF.175-182)

Many of his observations and inventions arose from daily life. He saw the waste of heating a room, so to retain the heat of a fire and draw away its smoke  he created the cast-iron “Franklin stove,” eight times as efficient as the then-common open hearth. He got tired of changing his glasses from one pair to another, so he invented bifocals. Both sound obvious to us perhaps--perhaps as only what is now familiar can.

Franklin’s breakthroughs are so fundamental to our lives that they recede into the background; like the terms he coined, what was once mythological is now quotidian. As their provenance recedes further into history and their usage broadens evermore into the future, his contributions become each like a grounded electric charge: distributed uniformly across the Earth, yet perceptible hardly at all.

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