Mars was a lively destination in early science fiction because of its proximity. When H. G. Wells needed a danger from outer space, The War of the Worlds naturally looked toward Mars, as a place close to Earth and one with the ability to provoke curiosity. Closely studied at opposition in 1877, Mars provoked in Giovanni Schiaparelli the prospect of a network of canals, surely feeding a civilization that might still be alive. No wonder new technologies turned toward the Red Planet as they became available to move beyond visible light and even attempt to make contact with its inhabitants.
All this comes to mind this morning because of an intriguing story sent along by my friend Al Jackson, whose work on interstellar propulsion is well known in these pages, as is his deep involvement with the Apollo program. Al had never heard of the incident described in the story. It occurred in 1924, when at another Martian opposition (an orbital alignment bringing Earth and Mars as close as they’ll get during its 26-month orbit), the U. S. Navy imposed radio silence nationwide for five minutes once an hour from August 21 to 24. The plan: Allow observatories worldwide to listen for Martians.
Image: The cover of the Edgar Rice Burroughs novel that would have been on Mars enthusiasts’ shelves when the 1924 opposition occurred. Burroughs’ depiction of Mars was hugely popular in its day.
This was serious SETI for its day. A dirigible was launched from the U. S. Naval Observatory carrying radio equipment for these observations, with the capability of relaying its signals back to a laboratory on the ground. A military cryptographer was brought in to monitor the situation, as attested by a provocative New York Times headline from August 23 of that year: “Code Expert Ready for Message.; RADIO HEARS THINGS AS MARS NEARS US.”
All this was news to me too, and thus I was entranced by the new article, a Times essay from August 20 of this year, written by Becky Ferreira. Because something indeed happened and was reported in August 28 of 1924, again in the Times: “SEEKS SIGN FROM MARS IN 38-FOOT RADIO FILM; Dr. Todd Will Study Photograph of Mysterious Dots and Dashes Recently Recorded.”
As Ferreira explains::
A series of dots and dashes, captured by an airborne antenna, produced a photographic record of “a crudely drawn face,” according to news reports. The tantalizing results and subsequent media frenzy inflamed the public’s imagination. It seemed as if Mars was speaking, but what was it trying to say?
“The film shows a repetition, at intervals of about a half hour, of what appears to be a man’s face,” one of the experiment’s leaders said days later.
You may recall that when Frank Drake began Project Ozma at Green Bank in 1960, he homed in on nearby stars Tau Ceti and Epsilon Eridani. And relatively soon he got a strong signal, causing him to ponder whether detecting other civilizations might be easy if you just pointed your antenna and began to listen. But the signal turned out to be from an aircraft in the skies of West Virginia, an early SETI frustration, for radio frequency interference (RFI) is a source of constant concern, as witness the stir caused briefly in 2019 by what appeared to be a signal from Proxima Centauri, but was not.
I don’t think the 1960 RFI experience got much media play, if any, though Project Ozma itself received a certain degree of coverage. But the ‘face’ found in the Mars radio reception of 1924 would have caused newspaper readers in that year to recall Guglielmo Marconi’s 1920 claim that he had detected signals “sent by the inhabitants of other planets to the inhabitants of Earth.” This was an era bristling with the new exploration of radio wavelengths, which if they could offer communications across a continent or ocean, could surely make possible a signal from one planet to another.
The interest was international, as another Times headline makes clear, this one from August 23, 1924: “RADIO HEARS THINGS AS MARS NEARS US; A 24-Tube Set in England Picks Up Strong Signals Made in Harsh Dots. VANCOUVER ALSO FAVORED At Washington the Translator of McLean Telegrams Stands by to Decode Any Message.”
Back to the ‘face’ found in the research effort on the American side of the Atlantic, dug out of data relayed from the dirigible. It was an astronomer named David Peck Todd who went to work with inventor Charles Francis Jenkins, using a radio from the National Electrical Supply Company designed to support troops in combat. Jenkins would use it to pick up any signals from Mars as detected by the airship. He had for his part built a ‘radio camera’ that would convert the radio data into optical flashes that would be imprinted on photographic paper, and it was within the result that what seemed to be a face emerged. But it was one that not everyone saw.
Jenkins himself was unimpressed, as I learned from a story titled “Freakish Radio writings on Mars Machine” that ran in the Daily News on August 27. Let me quote the small piece in its entirety:
C. Francis Jenkins, Washington inventor, is investigating to ascertain cause of a series of freakish writings received on his special machine designed to record any possible radio signals from Mars.
The film record shows an arrangement of dots and dashes and pictures resembling a human face.
“I do not think the results have anything to do with Mars,” Jenkins said.
A little more digging in the newspaper archives revealed that Jenkins told Associated Press reporters, as recorded in the Buffalo Evening Times that same day (“Radio Signals Shown on Films, Puzzle Savants at Capital”) that he thought the results came from radio frequency interference, saying what appears to be a face is “a freak which we can’t explain.” The image was indeed part of a repeating pattern recorded on Jenkins’ machine, but people were reading into it what they wanted to see.
Image: What remains of the 1924 ‘face on Mars’ detection, as captured through photography of the original paper roll produced by Jenkins in his lab. Credit: Yale University Library.
So where is the 38-foot long roll of photographic paper that caused the ‘detection’ of a face from Mars? The original, according to Ferreira’s research, seems to have been lost, but Yale University Library lists three images from its collection of materials on David Peck Todd under the title “Martian signals recorded by Jenkins.” So we have at least three photographs of Jenkins’ work, but to me at least, no face seems apparent.
Also in Buffalo, the Buffalo American ran a much longer piece titled “Astronomers Scan Mars To Discover Human Life” for its August 28, 1924 issue, which looks at the whole issue of studying Mars, though without mention of Jenkins’ work. It includes this interesting paragraph:
…perhaps Mars does see what is happening on the earth. If you were on Mars and looked at the earth you would see a star twice as large as Mars appears to Buffalo, as the earth is double Mars’ size. In the far distance on the same side of the sky would be the sun but it would only be two-thirds as large as it appears here. On the other wise would be discerned a huge mass of vapor 1,300 times as large as the earth. That would be Jupiter, which has not solidified yet. You would also see a couple of moons. They light Mars at night and are responsible for the tides on its oceans.
The Buffalo American article takes us right into the Barsoom of Edgar Rice Burroughs’ imagination, which at that time had reached, in its 10-book series, The Chessmen of Mars (1922). If you’re a hard-core Burroughs fan, you may remember the chess game (known on Mars as Jetan) in which humans play the role of the chess pieces and fight to the death (Burroughs loved chess). Despite the Buffalo American’s mention of oceans, even in John Carter’s day Barsoom was depicted as a place where water resources were rare and tightly controlled.
And just why study Mars in the first place? The newspaper article explains:
They want to know if the earth is the only celestial globe on which the Creator put human beings and if the planets and stars beyond were designed merely for the people on Earth to admire.
The Mars of the day was an extraordinary place. In researching this piece, I came across this from an article on the 1924 opposition by Rowland Thomas that ran in the St. Louis Post-Dispatch:
For some time astronomers all over the world have been preparing to get close-ups of Mars with their telescopes. The observers at Lowell Observatory, Flagstaff, Ariz., where the late Percival Lowell carried on his lifelong study of the planet which confirmed his belief that intelligent life exists on it, reported that on the southern hemisphere of Mars, where the polar ice cap is now melting under the rays of what is there a spring-tide sun, vast areas of what may be continents, marshland, prairies and the beds of dired-up oceans are constantly changing in appearance.
Image: Mars as conceived by astronomer Percival Lowell (1855-1916) and discussed by him in three books: Mars (1895), Mars and Its Canals (1906), and Mars As the Abode of Life (1908). The canals are here shown filled, with the vegetation in vigorous growth. Painting by H. Seppings Wright (1850-1937).
We’re still fourteen years from Orson Welles’ “War of the Worlds” broadcast in October of 1938, which gave plenty of time for early SETI interest to grow along with magazine science fiction, which in the US began in the pages of Hugo Gernsback’s radio magazines starting with The Electrical Experimenter and moving on to Science and Invention, but would soon claim its own dedicated title in Amazing Stories, whose first issue appeared in April of 1926. A nod as well to a sprinkling of earlier SF stories in Street & Smith’s pulp The Thrill Book.
Ferreira’s article is terrific, and I’m glad to hear that she is working on a book on SETI. It took Mariner 4’s flyby in 1965 to finally demonstrate what the surface of Mars was really like, and by then the interstellar SETI effort was just beginning to get attention. I wonder how the Mars enthusiasts of 1924 would have reacted to the news that despite the SETI efforts of the ensuing 100 years, we still have no proof of intelligence or indeed life of any kind on another world?
Only a hundred years ago…these reports and speculations must have sounded very convincing to our parents. And a century is trivial in the great scheme of things, both of my parents were born over a hundred years ago.
I recall reading reports of visual astronomers documenting green vegetation spreading from the Martian poles as the icecaps melted in spring–and of spectroscopy hinting at the presence of chlorophyll!. These observations were from way before my time, but were still being cited and debated as evidence of the canals when I was a student. I also recall reading about one astronomer glimpsing a huge white “W” shaped feature on the Martian surface during a moment of exceptionally clear seeing during a particularly close opposition. Was this the Martians trying to signal us by lighting fires, or using smoke? Serious proposals were made to light forest fires in the Siberian taiga to answer this signal
We must remember, that Mars is faint through the telescope, and only a time exposure could reveal detail on the slow photographic emulsions of that time. But the planet rotates, and long exposures were blurred! The planet is close enough for visual examination only at opposition, for a few weeks every few years, and our own atmosphere is turbulent and cloudy. Even back then, we knew dust storms frequently obscured the Martian surface, and these often seemed to coincide with the times the planets were in best alignment for telescopic inspection. Mars was always at the extreme limit of possible observation, always at the very edge of wonder.
None of us is immune to this sort of self-deception. I once recall seeing (through a telescope) a huge rectangular structure on the surface of the moon, like an immense bridge spanning a miles- wide crater! Of course, the next night it wasn’t there, just a trick of light and shadow and perspective.
But these reports can tell us more about ourselves than they do about the Martians. Someone could see a “face” in those Martian scans in 1924, but what makes us think Martians would even have faces? And we are still seeing humanoid faces on Mars today.
Victorian UFOs looked like balloons and gliders…we tend to see what we expect to see.
As witness the ‘phantom airship’ of 1897.
Initially, I was wondering how the 1924 signal was converted from a 1D stream to a 2D face. How would they know to think of breaking it up into lines like a tv signal that had not been invented yet?
But with the image of the signal, I do see what was meant by faces. The top stream can be seen as “hair”, with 2 “eyes” (and sometimes “eyebrows” below it). then a smudge that could be a “nose”, and a smudge below that is a “mouth”. In at least one case that smudge mouth looks like it is smiling.
So lots of repeating “faces” in the signal.
An appropriate example of humans seeing things that are not there, just as Lowell saw canals and vegetation, and with them he “logically” built a dying civilization, not unlike the scenario Wells had used for his “War of the Worlds”.
It is a lot easier to see the faces in that signal, than the compounds encoded in the “A Sign from Space” signal that took a long time to interpret successfully.
In 1924 there was enough radio equipment and probably unscreened electrical motors, that the US Navy could not enforce true radio silence even in the USA, let alone any signals from a distance bouncing off the ionosphere. A repeating signal like that received was mostly likely RFI from a machine. It would be ironic if the signal emanated from something on board the dirigible itself, such as a generator on the engines to power the radio equipment.
I remember reading somewhere that by the turn of twentieth century raster images were being transmitted through the Transatlantic undersea cable. European and American newspaper readers could see recognizable portraits of individuals across an ocean just hours after their assumption of notoriety.
@Hewnry,
Thanks for the correction. I had thought that such raster approach was later, Wikipedia confirms your memory. https://en.wikipedia.org/wiki/Wirephoto
If you have ever watched the charming TV series “Murdoch Mysteries” (AKA “The Artful Detective”) set at the turn of the 20th century, in Toronto, Det. William Murdoch is always inventing technologies ahead of its time that help solve a case, and this was one of those inventions. The series always named them in reference to later technologies, e.g. “Finger Marks” for fingerprinting.
Here is a collection of good articles on the Mars broadcasts of 1924, with the first ones having many relevant links on the subject. None of these are simple rehashes on the topic and all contain something of unique value to this fascinating essay:
https://www.atlasobscura.com/articles/radio-signals-from-mars
https://www.thehenryford.org/explore/blog/listening-to-mars–celebrating-the-100th-anniversary-of-the-1924-mars-opposition
https://www.earlyradiohistory.us/mars.htm
https://airandspace.si.edu/air-and-space-quarterly/issue-11/search-for-extraterrestrial-intelligence
https://www.shorpy.com/node/12482
https://www.detroitnews.com/story/news/nation/2024/08/24/100-years-ago-the-big-listen-tuned-in-to-messages-from-mars/74924170007/
https://artdaily.com/news/173197/Scientists-seeking-life-on-Mars-heard-a-signal-that-hinted-at-the-future
https://www.washingtonpost.com/history/2024/08/23/1924-search-for-aliens-mars/
Do not be too concerned with the moniker of UFO in these next two titles:
https://www.denofgeek.com/culture/real-ufo-history-radio-signals-aliens/
https://ufopast.com/2016/12/28/martian-signals-and-the-national-radio-silence-day-of-1924/
Here is the unbroken link from Yale library archives:
https://findit.library.yale.edu/catalog/digcoll:4345925
Here is an article from 1920 on the subject of radio signals to and from Mars:
https://onetuberadio.com/2020/01/28/1920-radio-communications-with-mars/
As usual, Tesla was ahead of the game:
https://teslauniverse.com/nikola-tesla/articles/talking-planets
I am reminded, among other things, of the discourse on the famous Wow! Signal of 1977 and how our limited technology of the day has led to debates on what it was ever since. I highly recommend this video on the event:
https://www.youtube.com/watch?v=TjQUucV83w4
Percival Lowell may have been off about the Canals of Mars. He may even have not been the best draftsman when attempting to reproduce what he saw through the telescope, but he was a very good writer. Check out this sample from his 1895 book Mars as the Abode of Life here:
https://avalonlibrary.net/ebooks/Percival%20Lowell%20-%20Mars%20As%20The%20Abode%20of%20Life.pdf
As for mind beyond the confines of our tiny globe, modesty, backed by a probability little short of demonstration, forbids the thought that we are the sole thinkers in this great universe.
That we are the only minds in space it takes indeed a very small mind to fancy. Our
relative insignificance commonly escapes us. If we reduce the universe to a scale on which we can conceive it, that on which the earth shall be represented by a good-sized pea, with a grain of mustard seed, the moon, circling about it at a distance of seven inches, the sun would be a globe two feet in diameter, two hundred and twenty feet away.
Mars, a much smaller pea, would circle round the two-foot globe, three hundred and fifty feet from its surface; Jupiter, an orange, at a distance of a quarter of a mile; Saturn, a small orange, at two fifths of a mile; and Uranus and Neptune, good-sized plums, three quarters of a mile and a mile and a quarter away, respectively.
The nearest star would lie two hundred and thirty thousand miles off, or at about the actual distance of our own moon, and the other stars at corresponding distances beyond that; that is, on a scale upon which the moon should be but seven inches off, the nearest star would still be as far from us as the moon is now.
When we think that each of these stars is probably the centre of a solar system on a grander scale than our own, we cannot seriously take ourselves to be the only minds in the universe.
But improbable as the absence of ultra-terrestrial life in a general way is, up to the
present time we have had no proof of its particular existence in worlds beyond our own.
Whether the observations I am now to describe have revealed something on the point I shall leave the reader himself to judge, after laying the facts before him; for it is with this in view that the present papers will deal with Mars, since any answer on this point is the most generally interesting outcome of a study of the planet.
That the observations also disclose the fact that the hitherto accepted period of its rotation proves to be too small by the hundredth of a second is a matter of far greater moment, of course, but one which leaves the average man comparatively cool.
That Mars, however, should be peopled by intelligent beings, although physically they be utterly unlike us, more goblins than men or animals, is a suggestion which appeals romantically, at least, to everybody.
To determine whether a planet be the abode of life, two questions about it must be answered in turn: first, are its physical conditions such as to render it habitable? and secondly, are there any signs of its actual habitation? Unless we can answer the first point satisfactorily, it were futile to seek for evidence of the second.
And here is the online version of Lowell’s work from 1906 titled Mars and Its Canals, complete with illustrations:
https://www.gutenberg.org/files/47015/47015-h/47015-h.htm
So glad to see your references here to Edgar Rice Burroughs’ Mars series, Paul.
So, yes, I guess include me as a “hard-core Burroughs fan,” lol.
I know that – this quite early – work sometimes is dismissed as pulp fiction; but, even if perhaps so, I don’t readily dismiss work that inspires and stirs the imagination.
Who knows how much Burroughs’ early work in the overall genre inspired and stirred the imaginations of later sci fi writers in their youth.
First we dream, and then we reach further.
In my family, A Princess of Mars – per his 1922 handwritten inscription on the flyleaf – was “Book 3″ in the budding library of my then maybe 12-year-old maternal grandfather (to be, of course), with whom I share two-thirds of my name.
His hard cover editions from the series – starting in 1917 by that particular publisher – were passed down to my generation and similarly inspired and stirred our imaginations.
Those books in part are why I ultimately began working during personal time, later as a lawyer, on a draft constitution for an eventual settlement of Mars – as a purportedly grown up version of the young boy who had been inspired by Burroughs’ Mars series.
And those books definitely are why I refer to that draft document as “A Constitution of Mars,” as an homage.
(Looking to try to get an initial installment – within, yes, a series – to you for possible editorial review for hopefully early 2025.)
It would be interesting to see the contemporaneous edition with the color cover art work from The Chessmen of Mars that you have in your first image.
The hard cover editions from my family’s library instead have more traditional book covers, i.e., book title and author with no cover art. But they include J. Allen St. John’s illustrations interspersed in the volumes in moderately glossy prints in black and white tones – with that particular cover art being found thus instead in black and white toward the end of my family’s 1922 Grossett & Dunlap edition of that volume.
Those illustrations were very much an integral part of the allure of the Mars series.
And they inspired as well a next generation of also graphic artists, including Frank Frazetta. I had been thinking that they were “Frazetta-like before Frazetta” – until I saw in doing background research for this note that Frazetta indeed was a disciple of St. John, as per Wikipedia. And Frazetta himself later did do a number of illustrations based upon the Mars series in the 1960’s and ‘70’s.
Burroughs’ – and St. John’s – work most definitely will remain part of the fabric of imagination that we have woven about one of our nearest planetary neighbors. And will remain so regardless of what science since has taught regarding the planet – ultimately to provide even more fuel for the imaginations of those who see its orangish red light seemingly so close in our night sky, particularly while in opposition.
I’m sure those Mars enthusiasts of 1924, including perhaps my then teenage grandfather (to be), would still – if they knew what we know now – be looking out to the heavens with enthusiasm.
Especially now that we know how many other worlds are out there – and no doubt are yet to be discovered out there – over and above Mars and our own solar system.
Doubting all the while that those worlds were hung there in the firmament “merely for the people on Earth to admire.”
Thanks so much, George. What a wonderful reminiscence. I have many fine memories of reading Burroughs when the paperback editions started flooding the newsstands back in the 1960s, and discovering Barsoom and the other science fictional venues, not to mention Tarzan. I remember how wonderful it felt knowing there were so many of these books out there, though I never did read the complete Burroughs corpus.
It is interesting that the cover by J. Allen St. John has been reused on the cover of different printings for nearly a century!
Chessmen of Mars covers.
Some staying power.
The bizarre Russian silent film _Aelita, Queen of Mars_ used the mystery radio signals as a topical way to drive the plot. A radio engineer at the Moscow radio station (who is, for reasons I won’t go into, disguising himself as a _different_ engineer at the Moscow radio station) detects the signals and in what looks like a long-weekend craft project, builds a rocket to go to Mars. He’s accompanied by a heroic Red Army veteran and a comic-relief secret police spy, because this is Bolshevik Russia after all. Various hijinks ensue, including a revolution and some of the most astonishing costume designs you’ve ever seen.
You cannot mention this film Aelita and tease readers about it then not show them where they can find and watch it…
https://www.youtube.com/watch?v=U1bd5wtXTNQ
https://www.youtube.com/watch?v=p86KJCF4pkk
Carl Sagan discusses the state of Mars knowledge before the Space Age:
https://youtu.be/IDyx6f5J6ro?si=w01d_EWn0Ujei5CQ
Then after Mariner 9 but before Viking:
https://youtu.be/cp5DgFfuExk?si=KyaaHBiHSFAdblIX
A fascinating look at Mars via Disney from 1957. Even some professional astronomers were still wondering if Sol 4 has or had intelligent life…
https://youtu.be/lHVrY4B7uzY?si=4LHvCVGutY3vu0fV
The idea of “Martians” was discredited starting around this time. But what I call the “Lowellian” environmental Mars, defined as a Mars where you could walk around wearing only breathing gear and where there was plant life, persisted right up until the Mariner 4 flyby in July of 1965.
The Arthur Clarke novel “Sands of Mars” depicted such a Lowellian Mars. He wrote it around 1949.
The first SF novel I ever read, in 1953, was Red Planet , Robert Heinlein, 1949. It had ‘Lowell’s’ Old Mars as a setting. So did Bradbury’s Martian Chronicles , tho that was kind of Alternate Universe Old Mars. I can’t remember but seems Clarke did not have ‘Lowell’s’ Mars in Sands of Mars.
I am sure ‘Lowell’s’ Mars shows up in other SF stories 30s , 40’s and 50’s. By 1950, actually starting in the 1940’s SF authors were getting tired of the solar system, and most space travel stories went Interstellar.
I know that there was more Mars stories and Novels after Mariner 4 in SF , those had the New Mars.
It is interesting that by the early 1920s astronomers had cast doubt on the Canals. By 1950 in the professional astronomy community Old Mars was not the accepted model, but I guess, this was not the general knowledge to SF writers , I guess?
(One notes there an Old Mars anthology of SF short Stories using Old Mars , 2013 Old Mars. )
Hello
The brain’s ability to create images is known: it is the pareidolia…the imagination & enthusiam for new technologies during the 20’s does the rest.
Technically speaking, at the time when radio was still on simple analogue low frequencies, the signal seen on the Jenkins roll reminds me of the RFI generated by the huge electric turbines of unshielded or poorly shielded industrial machines. The H Ford page below also offers electric streetcar ; we were still in the electrical-industrial age…
On this link, you can see the receiver of Jenkins (a real radio strainer in wood ! :) and the message sent by the Navy : Henry will tell us what he thinks ;)
All this makes us smile today but what is interesting is precisely that the authorities have become involved in the game. Imagine today that governments decide to block for example all satellite communications for 1 hour on a simple assumption !
https://en.wikipedia.org/wiki/Pareidolia
https://www.thehenryford.org/explore/blog/reaching-for-mars
still some interesting information found in the very serious French magazine “science & vie” of September 1924. P49
We talk about this earth-mars conjunction and the author Lucien Rudaux specifies:”that the planets were in similar positions” – something that recurs about every 15 years – and indicates a very close distance of 55,577,000km. The article also talks about the difficulties of observing the earth’s atmosphere…the photos are from the time.
https://cnum.cnam.fr/PDF/cnum_SCVIE.087.pdf
Jenkins & Todd & their devise here : https://www.shorpy.com/node/12482
humm…only electrical cables (in woven fabrics? ) and in 110v had to “pick up” everything that was lying around like RFI:) here we see the radio receiver which was intended for aviation who were therefore probably working on wavelengths 20; 40 and 80m (the antenna was used to lay the clothes for madam :) and the speaker on the table.
I suppose that the transcription of the signal on paper was the ancestor of the Belinograph so we should not be too surprised by the impulses we see on paper. The newspaper article is also interesting since it tells us that the US government had also contact Cuba; Venezuela etc.
A nice page of history.
https://jonathanmorse.blog/tag/david-peck-todd/
https://www.si.edu/object/receiver-radio-navy-se-950-nc-4-type:nasm_A19550027000
The National Film and Sound Archive of Australia cleaned up Alita in 2018:
https://www.nfsa.gov.au/latest/aelita-queen-mars-digitised?fbclid=IwY2xjawFIqTlleHRuA2FlbQIxMQABHZlD0nvqI_Qw4lZcodKS5siD5qGB8JD50AdYiP0mWXzRtdHB6RuJenAuPw_aem_upTu24YvFR3fNxjtN-sbLg
Aelita is a film UFO that must be seen as innovative but the film must be placed in the context of Soviet Russia at the time. if there is an idea of SF, it is above all an apologia of communism and a critique of the capitalist world but there is also a kind of moral when one understands from where comes the famous message of March shown at the beginning of the film. I do not tell…
Jenkins & Todd worked with a receiver on ~6m wavelength or ~54.5 khz therefore in LF. Here page 23, an article that talks about the experience. We also learn that Todd had proposed a kind of light emitter to Mars formed by a mine crater filled with mercury in which there would be a light source…
http://www.bigear.org/CSMO/PDF/CS04/cs04all.pdf
Two other points are interesting and reflect the state of mind of the time: on the pictures of the graph, Todd writes that he “granted the receiver as much as possible”…they assumed therefore that the Martians would communicate on one frequency or it would be enough to tune ! (I imagine the SETI point today the radiotelescope, press the button of the filter DSP make a coffee and have E.T on live…it would be too easy :)
but more importantly, Todd & Jenkins were — listening — (it’s a receiver and not an emitter) so they assumed technologically advanced worlds. It will also be noted that this was obviously no problem for the army or government to chat quietly with March in 1924 while a few decades later there will be a violent controversy about whether or not to communicate with other civilizations E.T
a look well we can actually see faces lying and profile on the band of the top…I also see little pigs : https://ibb.co/n1kSYCM