"We suppose as aforesaid, That Electrical Fire is a common Element, of which every one of the three Persons abovementioned has his equal Share before any Operation is begun with the Tube. A who stands on Wax, and rubs the Tube, collects the Electrical Fire from himself into the Glass; and his Communication with the common Stock being cut off by the Wax, his Body is not again immediately supply’d. B, who stands upon Wax likewise, passing his Knuckle along near the Tube, receives the Fire which was collected by the Glass from A; and his Communication with the common Stock being likewise cutt off, he retains the additional Quantity received. to C, standing on the Floor, both appear to be electrised; for he having only the middle Quantity of Electrical Fire receives a Spark on approaching B, who has an over-quantity, but gives one to A, who has an under-quantity. If A and B touch each other, the Spark between them is stronger, because the Difference between them is greater. After such Touch, there is no Spark between either of them and C; because the Electrical Fire in all is reduced to the original Equality. If they touch while Electrising, the Equality is never destroyed, the Fire only circulating. Hence have arisen some new Terms among us. We say B (and other Bodies alike circumstanced) are electrised positively; A negatively: Or rather B is electrised plus and A minus. And we daily in our Experiments electrise Bodies plus or minus as we think proper. These Terms we may use till your Philosophers give us better. To electrise plus or minus, no more needs to be known than this; that the Parts of the Tube or Sphere, that are rub’d, do, in the Instant of the Friction, attract the Electrical Fire, and therefore take it from the Thing rubbing: the same Parts immediately, as the Friction upon them ceases, are disposed to give the Fire they have received, to any Body that has less. Thus you may circulate it, as Mr. Watson has shewn; You may also accumulate or subtract it upon, or from any Body, as you connect it with the Rubber or with the Receiver; the Communication with the common Stock being cut off."
from Benjamin Franklin's letter to Peter Collison, May 25, 1747.
It’s really strange reading the words of such an intelligent person beginning to understand something back then that is so fundamental today that even laypeople understand it more scientifically. Really weird, but really cool to get a peek back into a scientific mind in the 1700s.
> even laypeople understand it more scientifically
Laypeople use more scientific-sounding words, sure, but what more scientific way is there to understand something than to have discovered it yourself through experiment?
Along similar lines, I recently learned about an early nuclear physics textbook written by George Gamow. The first edition came out in 1931, and the preface of the second edition in 1937 describes how the book had to be completely written because the state of knowledge had changed so radically in those few years -- most notably, by the discovery of the neutron and of induced radioactivity.
It's fun to think about a time when this stuff that we now take for granted as basic physics was not just new and poorly understood, but the forefront of knowledge was advancing so rapidly.
I haven't been able to find an online copy of the 1931 edition, but the 1937 edition is called Structure of Atomic Nuclei and Nuclear Transformations, and it's available through the Internet Archive: https://archive.org/details/in.ernet.dli.2015.501245
Is that official? In spanish, decades ago, the word for battery was "Pila"
"Pila" is a heap of countable physical units, either stacked or disordered. But pila is commonly a fixture for liquids, like septic tank is pila séptica
And batteries were mostly lead-acid. Hence, a pile for/of acid.
The main way that inductors function is by storing energy in a magnetic field, exactly analogous to the way capacitors store energy in an electric field.
If you apply a constant current to a capacitor, the voltage across the capacitor will increase linearly as the capacitor stores energy in the electric field.
If you apply a constant voltage to an inductor, the current through the inductor will increase linearly as the inductor stores energy in the magnetic field.
Perhaps part of why the intuition can break down is that in real life, inductors tend to be much "leakier" energy storage devices than capacitors. If you store some energy in an inductor and then change the voltage across it to zero (practically: short its terminals together), in theory a perfect inductor will maintain a constant current forever and the energy stored does not change. In practice inductors (with an exception for things like superconducting magnets) are made from wire that has a resistance, and so the current in a real shorted inductor will eventually decay to zero. This means that in practical terms inductors are mostly only useful for short term energy storage. On the other hand, real-life insulating materials (like air, vacuum, or Teflon) can can be pretty close to perfect insulators allowing real capacitors to store energy more or less indefinitely... certainly on timescales of years.
Seems like capacitors, inductors and batteries differ only quantitively in their response curves, not in qualitatively? As in they all do different things to the circuit on the voltage, amperage and time axis? We would need separate words for them, but accumulators seems like a decent umbrella.
Indeed! I love reading Benjamin Franklin for exaclty that. If you haven't read it, Walter Isaacson's biography on Franklin is absolutely fascinating. Brilliant, hilarious, driven, and wildly accomplished. The dude was (IMHO) one of the most interesting humans to have ever lived. Highly recommend.
This was how the 18th Century worked. In the 19th Century mathematical language became rigorous and formal, better able to handle more complex constructions accurately, but harder for lay people to learn, as it became a new language.
Well... going by the Fermi biography and the first few chapters of The Idea Factory (about Bell Labs) I would think this is what it always sounds like in the early stages of humans discovering a new part of nature.
It's just that our most recent theories have been so rich that we have happened to discover many things theoretically before we find them in real life. (Theory has preceded practice in recent decades, rather than the other way around which is historically more common.) I'm not sure this will always be so, it might be a temporary leap.
But his choice of "positive" or "negative" are entirely a convention of how he wanted to think about things. There's nothing special about the sign other than it made it easier for him to reason about what was happening.
>We say B (and other Bodies alike circumstanced) are electrised positively; A negatively: Or rather B is electrised plus and A minus. And we daily in our Experiments electrise Bodies plus or minus as we think proper. These Terms we may use till your Philosophers give us better.
Sounds like he leaves it open for future "Philosophers" to update the convention as our understanding of the phenomena that he had documented improved. Smart guy in not assuming that he got it right the first time. Franklin sounds like he wasn't a "my way or the highway" type of guy.
Hmm. "We rub our Tubes with Buck Skin", he says in the same letter. I was trying to work out whether the tube gets a positive or negative charge. I think it depends on what material is being rubbed with what:
I had ChatGPT-4o translate this to contemporary english
> We assume, as stated earlier, that electrical fire is a common element, equally shared among the three mentioned individuals before any operation with the tube begins. Person A, who stands on wax and rubs the tube, transfers the electrical fire from his body into the glass tube. Since his connection to the common stock is cut off by the wax, his body is not immediately replenished. Person B, also standing on wax, passes his knuckle near the tube and receives the electrical fire collected by the glass from A. B’s connection to the common stock is also cut off, so he retains the additional amount received. To person C, who is standing on the floor, both A and B appear electrified. C, having the normal amount of electrical fire, gets a spark when approaching B, who has an excess, and gives a spark to A, who has a deficit. If A and B touch, the spark between them is stronger because the difference in their electrical fire is greater. After they touch, there is no spark between either of them and C, as the electrical fire in all three is equalized. If they touch while being electrified, the equality is maintained, and the fire circulates continuously.
> This has led to new terms. We say B and similar bodies are positively electrified, and A is negatively electrified; or rather, B is electrified plus, and A minus. In our experiments, we electrify bodies as plus or minus as needed. These terms are used until philosophers provide better ones. To electrify plus or minus, it’s essential to know that the parts of the tube or sphere being rubbed attract the electrical fire from the rubbing object during friction. Once friction stops, these parts are ready to give the received fire to any body with less. Thus, the fire can be circulated, as Mr. Watson demonstrated, or accumulated or subtracted from any body, depending on the connection with the rubber or receiver, while cutting off communication with the common stock.
There's no rationale, merely a decision. He chose Earth as the source of electric fire, instead of a sink. It's a completely arbitrary choice, as light source vs dark sucker.
He could have thought instead that A is collecting Electric Fire from the glass rod. And when B touches the rod they recharge it losing some of their Electric Fire.
“These Terms we may use till your Philosophers give us better.”
Yes he had a rationale, the question is why it didn’t change once we knew better; he even called for it.
I mean, I think I know why it didn’t change at any given point - the standard was already in place and it always looks too difficult. But in retrospect, the effort in the 1800s would have been small compared to the effort 100 years later.
Maybe it’s still true that we should change the convention starting now, because the confusion and cost of not changing it in the future will continue to grow?
"We suppose as aforesaid, That Electrical Fire is a common Element, of which every one of the three Persons abovementioned has his equal Share before any Operation is begun with the Tube. A who stands on Wax, and rubs the Tube, collects the Electrical Fire from himself into the Glass; and his Communication with the common Stock being cut off by the Wax, his Body is not again immediately supply’d. B, who stands upon Wax likewise, passing his Knuckle along near the Tube, receives the Fire which was collected by the Glass from A; and his Communication with the common Stock being likewise cutt off, he retains the additional Quantity received. to C, standing on the Floor, both appear to be electrised; for he having only the middle Quantity of Electrical Fire receives a Spark on approaching B, who has an over-quantity, but gives one to A, who has an under-quantity. If A and B touch each other, the Spark between them is stronger, because the Difference between them is greater. After such Touch, there is no Spark between either of them and C; because the Electrical Fire in all is reduced to the original Equality. If they touch while Electrising, the Equality is never destroyed, the Fire only circulating. Hence have arisen some new Terms among us. We say B (and other Bodies alike circumstanced) are electrised positively; A negatively: Or rather B is electrised plus and A minus. And we daily in our Experiments electrise Bodies plus or minus as we think proper. These Terms we may use till your Philosophers give us better. To electrise plus or minus, no more needs to be known than this; that the Parts of the Tube or Sphere, that are rub’d, do, in the Instant of the Friction, attract the Electrical Fire, and therefore take it from the Thing rubbing: the same Parts immediately, as the Friction upon them ceases, are disposed to give the Fire they have received, to any Body that has less. Thus you may circulate it, as Mr. Watson has shewn; You may also accumulate or subtract it upon, or from any Body, as you connect it with the Rubber or with the Receiver; the Communication with the common Stock being cut off."
from Benjamin Franklin's letter to Peter Collison, May 25, 1747.