The Ether in 1897

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1897 was a fascinating year.  (Ignore the book jacket above for a minute.)  Dracula came out in May.  Ever read it?  Not seen the movie — but read the novel?  The original story was nothing like the Hollywood iteration, with bloody-mouthed babes in nightgowns and all that.  The original one is about science.  More accurately, it’s about inferential logic and epidemiology.  Read it, and you’ll see what I mean.  Dracula was published within a year or two of when (a) microbes were first seen under microscopes and (b) their relation to operating room infections was posited.

So 1897 is an age of modelling invisible systems that drive visible ones.

The ether.  Here I come to my point.  In case you wondered, the ether, in 1897, was understood to have a density expressible on the order of 10 to the minus-27th power, calculated somehow ‘from the energy with which the light from the sun strikes the earth.’  It is a substance so fine that atoms sit like marinated cherries within it.  It perfuses all matter in the universe, so that all physical things are in continuity with all other physical things.  Yet things are not continuous with the ether.  Vibrate the ether, and the vibration will pass through distant objects – but the objects themselves will not vibrate.  The earth does not push through the ether, like a boat; the ether allows the earth to pass, as water allows a moving sieve to pass.  Rays, of light or electricity or Röntgen beams, move as vibrations of the ether.  For reasons not yet understood, the ether will conduct every kind of ray through every kind of substance.  Nor does it conduct rays at the same speed through every substance.  The ether in glass carries light at about 120,000 miles per second; through the air, closer to 192,000.  Glass alone, with no ether inside it, allows light to pass at a pokey 3 miles per second.

Oliver Lodge posited that ether functioned in the physics of spiritual life in the afterworld.  That’s another post, probably not on this site.  He was still writing about ‘The Effect of Light on Long Ether Waves’ in 1919 (Nature volume 102, page 464).  ‘The Ether’ was still slang for radio at least into the ’20s.  That too is a whole ‘nother post.  (Now you can look at the illustration above.)

Marconi at Poldhu is only 5 years away now.  It’s amazing, what we can do with the wrong model sometimes.


Says who (except for the Dracula or Oliver Lodge parts):

H.J.W. Dam, “Telegraphing without Wires. A Possibility of Electrical Science,” McClure’s Magazine, March, 1897, pp. 383-92.

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For the scholars among us

Just to remind everyone, please help yourself to the growing Research Bibliography — look for it in the stack of links to your upper right.  It’s primary source-heavy, and it’s mostly about early wireless.  But it’s developing.  You’re welcome to tell me what more to put in it, too.  Drop me a line, and in it goes, with my thanks.  Meanwhile, browse it and use it!

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Technical Notes from 1908

WSB 1908

Electrician and Mechanic reader ‘W.S.B.’ wrote in from Brooklyn in the Autumn of 1908, with the picture above, to tell about his transmitting apparatus. He said this:

“Height of aerial to pole from spark-gap, about 25 feet, and the pole is 35 feet high, with umbrella aerial radiating from top of pole (eight ribs of 7-22 copper wire), each rib about 30 feet long, or total length of, say, 90 feet. Induction coil will give a 7½ inch spark. I use six glass plates, 10 X 12, with tin foil 7 X 9 inches on each side, connected in multiple, for my sending condenser, as shown by illustration. Battery, nine storage cells, worked at about 7 or 8 amperes. Have experimented quite a lot with independent interrupters, and I have now got one that will interrupt properly at a fast rate, and under current as above, without the points welding.”

This description referred to some concepts unfamiliar to me, though I’d heard the vocabulary. I went with questions to Roger Horton, K8CIX, contemporary builder of spark stations, who learned the art from his father and uncle, who started in the radio construction business in 1919.  See his magnificent site, Roger very generously filled me in on technical details I didn’t understand. My questions, and his answers, are below. Anyone who wants to know how spark radio worked should read this. Here are my queries, and here is what he said.

  1. Were antennas in 1908 pretty improvised? His sounds like an RF mess, designed just to get as much metal into the air as possible.

Well, it was early in the science and skin effect was known, so many experimenters did just as you describe and got as much wire up as possible, disregarding frequency or resonance.

  1. Is the induction coil the same as a tank circuit? Is its function just to build a voltage gradient big enough to arc?

No, the Helix or Helix Coil was actually a tank circuit that helped to determine the frequency of the emitted signal. It really had no use in the ARC performance. Really just a coupling device to couple the transmitter to the aerial. The induction coil was the coil at the beginning of the circuit that actually had a high turns ratio between the primary and secondary. Supplied with pulsed D.C. these coils usually developed between 14,000 and 20,000 volts which was then supplied to the Spark Gap.

  1. What is the condenser for? Is it a capacitor that just smooths out current?

Adding the condenser in spark gap technology was relatively simple. It entailed adding a capacitor across the secondary winding of the induction coil (or the spark gap) used to generate the spark. The addition of this single capacitor to the spark gap transmitter made a big difference. It eliminated the continuous arc which dragged down the voltage from the induction coil. Placing the capacitor across the secondary of the induction coil, in the transmitter, enabled both the gap current and the resulting antenna current to increase, and also the fast discharge of the capacitor removed the gap resistance from the antenna circuit. Both of these attributes come as a result of the addition of the single capacitor of approximately .05uF. The time it took the capacitor to charge kept the arc from occurring and at full charge the arc would then fire, also discharging the condenser and the sequence would start over, all occurring in milliseconds. This was called the oscillation or oscillator circuit. 

  1. What exactly is an interrupter?

There were 2 items referred to as interrupters. One, the device causing magnetic switching of the D.C. voltage supplied to the induction coil. This magnetically operated switch, called a buzzer or interrupter, usually was mounted on the front of the induction coil and the primary core of the coil caused the switch to interrupt the D.C. supply to the coil. The other type of interrupter was used in the ARC circuit to quench the spark gap and was called a Rotary Spark Gap.

  1. Why did the D.C. input current need to be pulsed? And I would have thought anyway that for a transformer, the current would have needed to be alternating.

Many of the places a spark gap transmitter was used had no access to A.C., but pulsed DC will operate an induction coil in place of the normal AC required to operate a transformer. Also, most of the early induction coils were designed for gas engines, such as autos, tractors, aircraft and hit & miss engines, and they ran on 6 vdc. 

If you remember back, just a few years, the automotive ignition system consisted of an induction coil, a set of points (interrupters), and a condenser, to create the spark or arc for the spark plugs.  

  1. And is the induction coil the same as a ‘loose coupler’, or is that for receiving?

Loose couplers are strictly for receiving using a crystal detector.


I am indebted to Roger Horton!  This makes early radio come alive.


Text and picture:  Electrician and Mechanic, October, 1908, p. 179, available at

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Club Life in 1908: snapshot of the wireless world

WSB 1908

1908 was a big year for wireless clubs.  They formed on the backs of magazines, typically electrical trade journals, whose pages hobbyists scoured for construction information.  It was natural that editors would encourage their attention.  Periodical sections devoted to these early clubs are very detailed pictures of the amateur community.  From their pages we can tell exactly who these people were, how they organized themselves, and what they could do technically.

The famous club is that of Luxembourg immigrant and future radio luminary Hugo Gernsback, who founded Modern Electrics in April, a catalogue that, due to demand, also contained features and articles.  On this circulation list in the following January he set up a “Wireless Association of America,” which, he claimed, gathered 10,000 members in its first year.

A less famous example is Electrician and Mechanic, which had its own newish club in place by August 1908.  Membership was 114, spread fairly evenly among 27 states and Ontario and Prince Edward Island.  Massachusetts had the most members, for some reason.  It was free to join, existing merely as a roster of stations and their descriptions.  Its function was simply to encourage local chapter meetings and exchange of information.  It grew quickly.  By October, the magazine ran a special article on the proliferation, and sophistication, of the amateurs in Baltimore, reckoning their number at 30, and their age-range from under fifteen to about 45.

Why Baltimore?  There was a professional nexus.  “Certain employees of the C. & P. Telephone Company, who advanced from the filings coherer stage to the tuned circuit and detector,” encouraged local enthusiasts, person-to-person, rather like a club.  Two others were ex-professionals as well, former operators of the De Forest station in town.  It was common that professional men used the good offices of their firms for non-commercial radio generally.  Providence reader ‘W.W.B.’ wrote in to ask for contacts in his city, offering a downtown place to meet at no cost.  “I am the department manager of a large firm,” he said.  “We could meet at my office and talk over the matter of forming a local branch.”

They really did need to talk with each other.  The wireless art was elevating so quickly that even the magazines were having trouble keeping up.  Reader ‘R.H.M’ in St. Paul, Minnesota, fretted that he could not get articles fast enough, particularly on high frequency transformers.  He wished that Electrician and Mechanic would devote a big section monthly to practical construction.  ‘C.W.W., of Melrose Highlands, Massachusetts, wished for an explanatory piece on the hot-wire ammeter, having tried in vain to find out how this instrument was made and how it worked.  The closed core transformer was the nucleus of the 1908 station.  ‘M.A.’, in Campobello, Massachusetts, wanted an article on building one, for about $10, that would work on 100 volts, 60 cycles per second, which is to say, house current.  Some stations, such as that of ‘W.S.B.’ (shown), stilled used batteries.  His used nine cells, delivering a goodly “7 or 8 amperes.”

W.S.B.’s station was in Brooklyn.  He had managed to talk with the De Forest station four miles away.  He received signals from Fire Island plainly, and could detect transmissions up the Connecticut coast, as far Wilson’s Point (off Norwalk) and Bridgeport.  His receiving range was thus about 50 miles.  He thought he may have heard ships farther off than that.

1908 must have been an exciting year.


Says who:

“ The Wireless Club,” Electrician and Mechanic, September 1908, pp. 137-8.

“Wireless Telegraph Stations in Baltimore,” Electrician and Mechanic, October 1908, p. 146.

“Wireless Club,” Electrician and Mechanic, October, 1908, p. 179.


Picture source:  Electrician and Mechanic, October, 1908, p. 179, available at

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Poldhu-Newfoundland 1901: actually a shortwave achievement?


It’s well-trammelled ground, over whether Marconi really got a low-frequency signal across the Atlantic in 1901, like he’s famous for doing.  More precisely, the issue is whether he could have.  We don’t know what frequency he was using (Marconi didn’t either), and there are gaps in our knowledge about his equipment.  So we don’t know for sure that it was possible.  But David Sumner, G3PVH, in a superb piece of reconstructive detective work, has shown that the big jump may well have happened – but not at low frequency.  If it happened, it very likely occurred by spurious emission in the 30 meter shortwave band.

It was John Belrose, VE2CV, who gave us the canonical 500 kHz, or 560 meters, at which we suppose the transmission occurred, and he it was who also pointed out the difficulty of a long-distance leap at that frequency, particularly during daylight.  There sits the problem.  But Sumner’s argument goes like this.  A spark transmitter can generate secondary signals with high peak power.  The ‘jigger’ coil Marconi was using may have a self-resonance at about 10 mHz.  The transmitting antenna, from what we know of it, could have been resonant at that frequency, as could the receiving antenna (which, incidentally, was wind-borne on its kite in the right direction for great-circle propagation).  The feed-point impedance at 10 mHz would suit Marconi’s particular coherer better than one at 500 kHz.  This coherer and the earphones he used form a sensitive enough detector to receive HF broadcasting.  Normal propagation on 30 meters at the time of Marconi’s documented reception is transatlantic.  (I myself have crossed the Atlantic on 10 mHz lots of times, and at 100 watts peak, not his 10 megawatts.)

The technical details of Sumner’s sleuthing are a gripping read.  He made his own jigger, after Ambrose Fleming’s Poldhu design, and tested it with an antenna.  He sourced a Collier-Marr ‘phone at the Oxford Museum of the History of Science.  He takes us through previous work on coherer curves, too, a fascinating trip all by itself.    It’s a magnificent article, and its bibliography is full of treasures for the scholar, as you’d expect.


Says who:

John S. Belrose, ‘A radioscientist’s reaction to Marconi’s first transatlantic wireless experiment,’ Conference Digest, 2001 IEEE Antennas & Propagation Society International Symposium, July 8-13, vol. 1, 22-5.

David Sumner, ‘UK to Newfoundland, 1901 Style – the possibility of HF communication,’ RadCom, July 2018, 44-54.

Picture:  Wikimedia Commons (

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Range, in 1897

‘So, how far could they get, say, in the 1890s?’  Basic question to be able to answer.  I’m put in mind of an astronomer friend, expert in quasars and black-body radiation, who blushed when she couldn’t tell a layman how far away Mars is.

If anyone asks you, say that in 1897 the Marconi system, in the hands of the army and navy, was good for two or three miles.

That means it was no longer an induction system.  It was ground wave.  ‘Even a mountain between the transmitter and receiver does not, it is said, prevent transmission[.]’  It’s not at all clear (and Marconi couldn’t say in the trans-Atlantic tests several years later) what the wavelength was.  (We think we know, but that’s another post.)

Says who:  ‘Topics of the Times,’ New York Times, May 26, 1897, p. 6.

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Amateurs underfoot in 1907

ruhmkorffAmateurs by 1907 were numerous, and intrusive, and many of them backward technically. Electrical World took notice of a policeman’s son in Washington who jammed the Navy Yard and harassed professional operators. From New York Lee De Forest thundered that the lad typified ‘the ubiquitous amateur with his high-school Ruhmkorf coil’ (pictured), who was not only a vandal but a slovenly practitioner of outdated and disruptive arts. Roving detectives were needed, and robust legislation at the Federal level. Improper damping was causing chaos, he foamed. Communications must be limited to the sustained oscillation methods. “The day of the barbarous spark discharge is numbered,” he prophesied, “and the sooner it is classed with the filings coherer the better.”

Says who:  Lee De Forest, “Interference with Wireless Messages,” Electrical World (June 22, 1907) XLIX, 25: 1270.

Picture source, forum page, Model T Ford Club of America.  Heinrich Daniel Ruhmkorff was a German instrument maker, d. 1877, who commercialized at mid-century earlier iterations of the induction coil.  This model is probably a Ford variant.  Amateurs cannibalized these routinely for spark gap transmitters.  The resulting signal was a wideband splatter.

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The fund of knowledge in 1898


The professional community was surprised, and skeptical, when Marconi began achieving reliable communication over long distances. Here is what they deemed knowable at the time they began paying attention.

They wondered what it was that activated the coherer. Magnetism? That doesn’t work, they found. So it was something else. Whatever it is, it even works in vacuums. ‘Making and breaking’ current in an electromagnet, with a ‘vibrator’ or an ‘interrupter’, is how you made a transformer create whatever it was; or you could use alternating current. Artificial daylight apparatus activated coherers, they saw. So did trolley lines. Both of these generated small amounts of spark. So maybe it had to do with spark. But not everyone thought spark was strictly necessary.   W.J. Clark told the New York American Institute of Electrical Engineers in 1898 that he was able to transmit short distances with no gap discharge at all. Marconi, he said, was surprised by this.

As for what these emanating currents did, Heaviside’s model was the gold standard for modelling them.  (Institute president in 1898, Arthur Kennelly (pictured), was so fascinated by this that propagation experts three years later came to speak of a Heaviside-Kennelly layer in the atmosphere.)  The emanating currents go in waves, they could tell for sure. Wave shape seemed to them like donuts. This seemed justified by J.J. Thomson following Maxwell. ‘Hertz waves’ and ‘Lodge waves’ looked like different things, however. Also, waves on the ground didn’t move like waves in the air, they could see as well. They reasoned that the surface of the earth ‘must be a conductor’. They could even tell that waves polarize, depending on whether antennas are vertical or horizontal. Transmitter builders were noticing that finer secondary coil wire worked better, too, though no one could say why.

Transmitting powers matter, they understood. Range goes up as power goes up. They reckoned that something like 95% of a spark coil’s power is used up in heat. They wondered if one could abate this simply with air-cooling, and make a better transmitter. Marconi’s school of thought in 1899 had it that you could also increase the length of your spark to increase your range. Longer spark length ought to mean stronger signals, owing to more EMF. But efficiency was a problem here. Each spark ‘is followed by a series of oscillations’, opined one Dr. Pupin (who also suspected that the number of sparks per second has something to do with the frequency of the signal). He imagined that the sparks dampened each other, depending on how rapidly they came. This attenuates signal strength (and it also generates spurious emissions on unknown and unknowable frequencies). He wished it were possible to generate oscillations without sparks. Hertz too had shown the importance at very high frequencies of finding some way to dampen rapidly decaying waves, for efficiency’s sake. People were talking about ‘decrement’, a special term for the decay rate of oscillations. Overcoming this problem was the rationale behind the ‘quenched gap’ a few years hence.

Marconi’s receiving apparatus was considered insensitive in 1899, a generally troublesome device worthy of abandonment as soon as possible. Coherers limited Morse code speed, to about 20 words per minute. No one had yet made exact measurements of what a coherer could do, partly because better techniques were already in sight. The super-sensitive receiver idea in 1898, the coherer being recognised as a blunt instrument, was a galvanometer. Whatever the receiver, they were inclined to think that signal strength that dissipated over distance requires a longer antenna to receive, because more wire accrues more volts.

Changing wire length brought its own problems. Engineers were aware of frequency changes, in a rudimentary way, and conceived of the possibility of tuning signals. 8-500 ‘breaks’ per second was the norm in 1898 spark transformers, and they could hear the corresponding variations in the musical pitch of the spark. This might be a way of tuning, they thought. Or maybe tuning was going to be a matter of condensers at the antenna feed-point, that control ‘damping’. They weren’t sure. C.O. Mailloux was adamant that transmitted waves resonate (and he used that word) at the receiving end only if the two sets were ‘synchronized’ with each other, so that the waves followed ‘in phase’. What this meant mathematically he wasn’t sure yet. Marconi himself was not even clear what the relationship was supposed to be between the height of sending and receiving wires. But broadly speaking, professionals knew that the electrical properties of transmitting and receiving wires ought to be as congruent as possible. They also knew that antenna size related to wavelength, and logically, that frequency is a function of wavelength. Fessenden declared that wave-length ‘is about four times the length of the wire’ used for transmitting. Thus it is that late Victorians were probably using quarter-wave verticals worked against the ground. (They could also tell that antenna ground connections were better on wet days.)


Says who: ‘The Possibilities of Wireless Telegraphy.’ Transactions of the American Institute of Electrical Engineers. 1899. 607-628. This is the transcript of a New York meeting, held on the same night as a parallel Institute meeting, in Chicago, to discuss Marconi, his assumptions, and his methods.


Photo:  IEEE Global History Network, link here.

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before commercial radio, commercial telegraph

Here are the telegraph men waiting on President Lincoln, played (superbly) by Daniel Day Lewis.  I wondered as I watched this how busy the lines really were.

Turns out, all-night press traffic by telegraph was big business by 1860.  Almost every US daily had signed up to the Associated Press news feed, now 10 years old.  The appetite for political news even before the Civil War was so voracious that by special arrangement the New York Herald got the transcript of a speech by Henry Clay hours after he spoke it in Kentucky, clear back in 1847.  It cost $500, which they were happy to pay.*  I notice that Augustus Melmotte, Trollope’s villain financier in the early ‘seventies, stayed in touch with San Francisco and Salt Lake City as though they were suburbs of London.**


Says who:

*George B. Prescott, History, Theory and Practice of the Electric Telegraph, 1860, p. 385 ff.

**The Way We Live Now, Chapter 10, first paragraph.  This is page 47 in the 1875 Harper edition.

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Reblogged from the ARRL: NPR’s “All Things Considered” Segment to Include Spark Gap Morse


Here is a lovely note from the American Radio Relay League’s blogsite yesterday, to which I was alerted by Twitter.  I’m reproducing it verbatim here.  ‘NPR’, for you Europeans, is ‘National Public Radio’, the listener-funded network for Americans who, if they lived in the UK, would be Guardian readers.  Listener-funding means people donate through period on-air appeals.  There is no government underwriting, and there are no adverts.  Anyway, this is a demonstration of spark transmission for the lay public.  I’ve shown spark before on our blog here, but let’s do it again.  Picture and text all copyright 2014 by the ARRL.


As part of its series of vignettes exploring a “counterfactual” history, “What if World War I had never happened?” NPR afternoon news magazine All Things Considered” will air a segment, to explore “What if the assassination of Archduke Franz Ferdinand was not successful?”

“They needed a sound of a telegraph relaying the message of the failed assassination attempt,” said ARRL Media and Public Relations Manager Sean Kutzko, KX9X. “They wanted it to be as authentic as possible, so we explained that in 1914, it would have been relayed via spark.”

The ARRL Lab has a working spark transmitter, so Kutzko got the desired text from NPR, which he sent by hand (yes, he’s a lefty) and recorded. “They said it was ‘perfect,’” he reported. “It was a real thrill being able to help NPR; I used to work at NPR affiliates in Illinois and Indiana in the 1990s, so being able to help the network was exciting.”

NPR’s “All Things Considered” typically airs at 4 PM Eastern Time (2000 UTC). ARRL Maryland-DC Section Manager Jim Cross, WI3N, believes the segment will air 35 minutes into the first hour of the show. The program segments are subsequently available on the NPR website. — Thanks to Maryland-DC Section Manager Jim Cross, WI3N, and Sean Kutzko, KX9X’

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