.
Blame Lin Carter for this one.   Here's the story, I got interested in the Callisto series, because of an essay written by Carter where he basically admitted that he was ripping off, or paying hommage to Barsoom.  He made no bones about it.  Basically, he wanted to do a Burroughsian interplanetary adventure, and he copied Barsoom closely.

Of course, Carter didn't want to use Mars for his "Barsoom" style adventure.  Obviously, it was already taken.   Michael Moorcock and Leigh Bracket got around that by catapulting their character far into the past, so that was out.    Venus and the Moon were out because Burroughs and Kline had already covered those grounds.

So that left the other worlds, Mercury and the giant satellites of Jupiter and Saturn beyond the asteroids.   The only trouble was that Manly Wade Wellman had already written Sojar of Titan back in 1941, during the pulp age.   Meanwhile, Mike Resnick, a contemporary of Carter and a Burroughs fan himself had turned out two novels about a Jovian Satellite...  Goddess of Ganymede and Pursuit on Ganymede in 1968.  So that was out.  And finally, Carter recalled that Mercury had been used by Ray Cummings for some distinctly Burroughsian adventures in Tama of the Light Country and Tama Princess of Mercury.   So that was out.   In the end, he decided to settle on Callisto.

But that kind of got me interested in some of these other pseudo-Burroughsian tales.   Who knows, someday I may dig up Sojar of Titan, or the two Ganymede novels and write about them.  But in the meantime, I wound up doing a bit of research on Ray Cummings and Tama.

Ray (Raymond King) Cummings (1887-1957) was one of the early pioneering pulp science fiction writers. Cummings' big claim to fame was that he was the only science fiction writer who had ever worked directly for Tom Edison as his assistant.

That was heavy mojo, Thomas Edison, inventor of the light bulb, the phonograph, the motion picture and about a jillion other things, founder of the electrical company that bears his name, was one of those strange polymaths that the age seemed to produce.   A kind of renaissance man of invention and technology.  He wasn't alone.  He shared his age with guys like Nikola Tesla, Alexander Graham Bell and even Henry Ford, the Wright Brothers, and Charles Lindbergh, experimenters and tinkerers who shaped much of the world we know today and who became legendary figures.

Nowadays it's all corporate.  Quick, can you name the guy who invented the VCR?  How about the cell phone?   There is no modern equivalent.   It would be as if Bill Gates or Steve Jobs, in addition to coming up with Microsoft and Apple Computers, also invented VCRs, Camcorders, giant foam styrofoam hands for football games, and were space shuttle pilots in their spare time.

Arguably, there was a fair bit of inflation in their legends, Edison, for instance, had an entire staff of inventors working for him.  Ford and Lindbergh just verged on being Nazi cranks.   The question of who really were the original creators of such things as telephones, motion picture projectors and light bulbs is disputed.   But during their heyday, and well into the late 20th century when everything got corporate, Edison was a near mythical figure.   Indeed, he was almost a character of fiction - magazines published the adventures of young Tom Edison, Tom Swift was a rip off of that.  And when reading audiences were shocked by Wells' War of the Worlds, well, lesser fiction writers were quick to set things right with adventures where Tom Edison and Nikola Tesla gave the Martians what for.

So for Cummings to be able to associate his name with the fabled Edison, that was heavy mojo.  Sadly, as is so often the case, there's less there than meets the eye.   Cummings in his five years as an assistant seems to have been mostly a clerk, not a junior inventor, his job seemed to be mostly labeling and cataloguing early phonograph records.   His signature can be found on many historical phonograph dicks.

Apart from the Cummings life featured the usual, sometimes hardscrabble, wanderings of many who would become writers.  He attended Princeton for a few months, lived in Puerto Rico where his family exported oranges, and later went to Wyoming where his father searched for oil, held various jobs before making it as a writer.

In 1919, he broke through as a writer with The Girl in the Golden Atom and never looked back.  Through the course of his pulp career, he published more than 1000 stories, mostly in genres other than science fiction and fantasy.   Of his SF work, it's estimated that he had roughly 150 stories, of which 21 were novel length.  His high water mark was the '20s and '30s, when he was the third most popular writer of his day, after A. Meritt and Edgar Rice Burroughs.

Criticisms of Cummings were that his style was pretty much static.   He didn't change or grow, he didn't experiment.   What he was writing, and how he was writing it was the same in the '40s as it was in the '20s, and the field was steadily passing him by.   He also seems to have borrowed considerably from Wells, aping elements of Wells structure and format, while jazzing it up with derring do and romantic adventure.   His introductions on the Tama stories have the feel of the cinema newsreels of the day.

My impression of his work was that it was basically serviceable.   A lot of it would pass muster as current Young Adult fare.   Although in his day called the "American H.G. Wells" that's simply huff.   Wells used his stories to talk about bigger issues, engaging in philosophical conceits.  His works can be explored for deeper themes and literary content.   Cummings basically wrote adventure stories, not too philosophical, not too scientific.  Fun and readable.   If we can damn Cummings with faint praise, it is that his work was not a slavish clone of better writers, for better or worse, he had his own voice and subject matter, even if it wasn't profoundly distinctive.

That said, I’m hardly an expert on the man.   My focus is on his Mercury stories, featuring winged women and battles of the sexes.    There are two principal novels, Tama of the Light Country, and Tama, Princess of Mercury, from 1930 and 1931 respectively.    The second title seems a fairly deliberate riff on A Princess of Mars suggesting that he was going for a Burroughs-style adventure.   Both of these novels are available as Ebooks for a relatively modest price.

In addition, he has a novel (published as a magazine serial but never as a book) called The Fire People from 1922, which deals with an invasion of Earth by monstrous denizens of Mercury's day side, and which features the Light Country and a race of winged women.   Unfortunately, it seems inconsistent in several respects with his Tama novels.   Basically, the Tama novels borrow or plagiarize from The Fire People but go off in different directions.   In the words of R.D. Mullen, while borrowing heavily from The Fire People, he changed important details and simply "wrote as if it did not exist."

His A Brand New World a 1928 story about a man encountering a winged girl from outer space also plays like a rip off of his own similar scene in The Fire People.   Meanwhile he's listed as having a 1940 short story called Aerita of the Light Country.   The spacecraft that his protagonist flies in the Tama stories seems borrowed from another of his own works Around the Universe.

The repeated use of Mercury as a setting or starting point, the origin of the Light Country and winged women, and the continuing recurrence of winged women between 1922 and 1940 across a writing career of decades suggests that these were strongly rooted in his imagination.   Not just throwaways, but things that resonated or rested powerfully within him.

Sadly, I've only got access to the two Tama novels.  It might be an interesting project to try and reconcile The Fire People and other works, but it won't be happening.   Instead, we'll take a good look at the Mercury of Ray Cummings.

---

The Modern History of the Real Mercury

---

So what is Cummings Mercury? As always, it draws on the science of the time, but not too heavily.   Even in the period 1922-1931, there was no real suggestion that Mercury was any more habitable than the Moon, and in fact, quite a bit to suggest that it was less habitable.

In the 16th or 17th century, there was some speculation that the moon was inhabited.  After all, it was a cosmic body like our own, there were features on it that appeared to be seas.  Astronomers with primitive telescopes discerned mountains and rivers.  Cyranno de Bergerac wrote an early science fiction tale about a visit to the moon and the strange inhabitants thereof.  Even as late as the early 19th century, in the 1830s, people like Edgar Allen Poe were telling tales of Moon men, and there was even a lively hoax in 1836 about observers discovery of bat winged lunarians.

But by the mid-19th century, it was pretty widely accepted that the moon was a dead and barren world.  As the years progressed, interest grew in both Mars and Venus as potential abodes for life.  But Mercury was never in any serious running.

Indeed, up until the 19th century, Mercury was known as little more than a bright star.  Being so close to the sun, there was little more that could be discerned of it, apart from its orbit.  Newtonian mathematics allowed for calculations of its mass, and size, but that was it.  Its diameter was approximately 3025 miles, or between the Moon and Mars in size.   However, it was a remarkably dense body, the densest in the solar system after Earth itself, which gave it a gravity of 38% of Earth's. In comparison, Martian Gravity was about 39% of Earth's.  Mercury's greater gravity came from its much greater density, it's estimated that the planet has a huge iron core.

Cummings was aware of this.  In Tama of the Light Country, he actually gets out his slide rule and has his protagonist tell us how much he weighs on Mercury, and what prodigious feats of strength and leaping he's capable of.

"...the gravity here is something less than half that of the Earth, they (local men) move about much as you do.   But it is not so with me here. On Earth I weight about a hundred and forty pounds. That is seventy pounds, more or less, here on Mercury. I can run with twelve-foot strides and leap some thirty or forty feet. The Mercutian men were afraid of me at first, but they are used to it now."

Less actually.   He's got it wrong.   Mercury's gravity is about 38% Earth's, so at a hundred and forty, he'd weigh about fifty-three pounds, give or take.  Obviously, his hero isn't up on his interplanetary gravity charts, and doesn't have an accurate set of measuring devices close at hand.  Mercurian scales probably dont read in imperial measurements.   His resulting athletic accomplishments are slightly more realistic, than John Carter's tremendous jumps.  Cummings also loads the dice a little bit by making the Mercurians a smaller race, the men average five feet, the women four and a half.   So his hero, Guy Palisse is both a giant and a superman among them.

In 1800, Johann Schroter made notes of surface features. Later in 1880, Schiaparelli, the same guy who observed canals on Mars, claimed to have mapped the surface.  Although Schiaparelli's maps were reasonably accurate under the circumstances, they didn't really catch on in any substantial way. Mercury didn't have big flashy features like polar caps that swelled and shrank with the year, proving the existence of water and earthlike season, it lacked dust storms that might occlude the planet and demonstrate the presence of a substantial atmosphere, nor did it possess defined mysterious bright and dark areas suggestive of continents and seas, and of course, those fabulous canals. Unlike Venus, there was no obvious cloud cover.

The inevitable conclusion was that Mercury clearly lacked water and lacked an atmosphere.   It lacked sufficient detail for any kind of flights of imagination.   Worse, its sun side was exposed to 6.5 times more solar radiation than Earth, which meant that it must be a blazing inferno.  While the far side was as cold as the dark side of the moon.  Even back in the 19th century, Mercury was seen as a dead and barren world.

Unlike Mars and Venus, Mercury never quite caught on in the pseudo-science thinking of the Victorian and post-Victorian age.   That thinking had Venus as the young immature world, Mars as the old tired world, and Earth as the happy middle.  The Moon might portend the far far future, the place where Mars was headed and Earth would eventually go.  But Mercury didn’t fit anywhere into the cosmic mythology of life and death.   So there were no great overarching narratives to it.

Instead, there was a sort of freakish curiousness about it.   Schiaparelli also suggested that Mercury's day was the same as its year, approximately 88 terrestrial days, meaning that the planet was tidal locked. One face permanently towards the sun, one face permanently in night. Schiaparelli's mappings of the surface, But Schiaparelli's other suggestion, of a world permanently tidal locked to the sun, as the moon was to Earth, took off.

The notion of a world with its two sides perpetually caught in light and dark respectively caught on with the public and science fiction writers. In the imagination and in fiction, Mercury's bright side was the hottest place in the solar system, and its permanent night side was the coldest. Well, as far as scientific romances went, this sort of sucked. Your alien princess, or her boyfriend, was likely to be instantly flash fried or freeze dried.

But, science fiction writers and scientists hypothesized, between them, was a permanent twilight, a kind of border area where tolerable conditions just might exist. Scientists pointed out, that it was still going to be pretty inhospitable, something close to the surface of the moon. But that was better than the inferno and icebox.

It was an attractive notion, because like Venus/Mars/Earth, it posited two extremes and a sort of happy medium, or balance between them.  The Victorians were big fans of happy mediums, it appealed to something in their world view.   They saw themselves as endlessly situated in a sweet spot, occupying an Island between seas and continents.   America saw itself as a favoured middle, between Europe and Asia, between two oceans, between the pole and the tropics.

A great many science fiction writers played with this notion of Mercury as a place of fire and ice. Isaac Asimov, notably, and Larry Niven, were two of the most prominent, but other writers like Alan Nourse and Arthur C. Clark went there.

Meanwhile, other writers, such as Ray Cummings and later Leigh Brackett, fantasized a habitable realm in Mercury's twilight, a place where there might be atmosphere and water sufficient for a civilization. After all, Mercury's gravity was almost the same as Mars, and people were willing to accept Martian adventures. So why not?   Truthfully, writers like Brackett and Cummings probably wouldn't have even bothered, except that Mars and Venus were already pretty crowded with earthborne adventurers and alien princesses.  Sometimes on Barsoom you couldn't throw a heavy rock without wrecking the rescue of some princess or other.   But even so, they didn’t actually do much with it.   There are even fewer "Mercury Adventures" than there are "Venus Adventures."

Actually, it turns out Schiaparelli was wrong.  In the 1960s, astronomers began bouncing radar beams off Mercury and discovered that its rotation period was 55 days.   Since its revolution period was 88 days, this meant that Mercury had three "days" or rotations, every two "years" or revolutions.

Ah well. It wouldn't have worked anyway. If Mercury had been truly tidal locked, the fierce solar rays would have heated the atmosphere, causing it to circulate rapidly to the dark side, which, permanently in darkness, would have been as cold or colder than pluto. There, it would have frozen out. In a short time, all the water on the planet would have inevitably been stored on the dark side. And after that, you'd have gotten all the carbon dioxide freezing out of the atmosphere and winding up on the dark side. And after that, the nitrogen and oxygen. After that, there wouldn't be any atmosphere to speak of. Certainly no atmosphere that could be breathed by Cummings or Brackett's humans. And of course, while that was happening, you'd get ferocious winds through the convection from day side to night side, before the atmosphere was permanently locked away. And those would make things pretty uninhabitable.

In the mid-1970s, a Pioneer spaceprobe swung by and took pictures of 48% of Mercury’s surface.   The images returned to Earth showed a sterile cratered landscape, not unlike the Moon, except that it lacked the prominent dark "Mares" or Lunar seas.   Basically, Mercury in the science of the Ray Cummings time, was a sunblasted rock, swinging rapidly around the sun. Not much has changed actually, it still is a sunblasted rock swinging rapidly around the sun.

Interestingly, one thing that radar imaging showed, was that Mercury stood tippy toe top side. That is, Mercury stands straight up. It has practically no axial tilt, or technically, 0.01, less than one one hundredth of one per cent axial tilt.  By way of comparison, the runner up, Jupiter's axial tilt is 3.13, or 313 times Mercury's.  By comparison Earth and Mars a staggering drunks wobbling around the solar system at 23.44 and 25.19 respectively.

What does this mean?   Without axial tilt, Mercury never has seasons.  Its poles do not wobble, they are always straight and true.  But it also means that Mercury actually really does have perpetual twilight zones. They're at the poles, broad flat areas which are permanently at the edge of light and dark.

Indeed, there are craters and valleys at the poles which have never had the sun shine into them, they have been eternally dark.  Scientists believe that Mercury actually has water there, at the bottom of these craters and valleys, protected from the scorching sun. Not a huge amount of water, they estimate, less than a tenth of that possessed by Mars, and Mars water is but a fraction of that possessed even by the Antarctic ice cap. But there you go. The fact that is has any at all is surpising.

Of course, there is a twilight band running around the rim of the planet.  But that band is not a permanent feature, rather, as the planet rotates, it sweeps slowly around Mercury, every fifty five days.  The result is that any part of the planet would only be in the "habitable" twilight for perhaps a maximum of  20 of those 55 days.  The cycle would be 10 days of "spring," 17.5 days of scorching summer.  10 days of ‘autumn’ and another 17.5 days of frigid winter.  Actually, given that Mercury has no atmosphere at all, that twilight band may be much narrower.  A day wide.   Perhaps an hour.  A minute.   Depends on how you slice it.

So, what else does science give us on Mercury?    Circumference 9525 miles.  Surface area, 28 million square miles.   It has a huge iron core, accounting for its density and remarkable gravity (Callisto which is slightly larger has a surface gravity of only 11%, or slightly less than 1/3).  Its internal core is believed to occupy 42% of the internal volume.  This is surrounded by a mantle, and then a crust 100 miles thick.

There's no sign that there was ever plate tectonics, and little sign of volcanism (although that is hotly debated and there are those who argue for recent active volcanism).  This is largely a dead world.  One interesting feature, however, is the presence of large ridges which are believed to be from cooling and shrinkage.   It's estimated that Mercury's crust might have shrunk by as much as a kilometer, causing immense folding and crunching.   It's a guess, we don't know all that much about how Mercury has developed.

There's one huge impact basin, Caloris, which sits on the equator.  810 miles in diameter, Caloris is ringed by mountains two miles high.   It's an impact on the scale of Hellas or Argyre on Mars.   On the other side of the planet from the impact is a strange jumbled disordered territory, suggesting that the shock wave went right through, it's believed that both the impact site and opposite side of the planet are associated with volcanism and outgassing of tenuous atmospheric constituents.

Another peculiarity of Mercury is its orbit.   At closest approach to the sun its roughly 28.5 million miles away, at its furthest, it is 43.5 million miles away.     A difference of 15 million miles, roughly half the distance to the sun at the closest approach and one third the distance at furthest approach.   This would mean that at closest, Mercury would be a hell of a lot hotter on its day side than at its most distant.   Since Mercury's days and years are in 3/2 synch, this means that there'd be a consistent pattern of "super-hot" days on specific parts of the planet on a regular basis.   Mercury also has a pronounced inclination to its orbit.  It isn't on the same plane as the rest of the planets.

These orbital peculiarities, together with Mercury's odd day and year would lead to strange astronomical results, as noted in the Nineplanets website:

"This fact and the high eccentricity of Mercury's orbit would produce very strange effects for an observer on Mercury's surface. At some longitudes the observer would see the Sun rise and then gradually increase in apparent size as it slowly moved toward the zenith. At that point the Sun would stop, briefly reverse course, and stop again before resuming its path toward the horizon and decreasing in apparent size. All the while the stars would be moving three times faster across the sky. Observers at other points on Mercury's surface would see different but equally bizarre motions."

Freaky, eh?   One wonders how Astronomers would have coped with a sky like that.

---

Cummings Mercury

---

For the most part, there aren't a lot of Mercury adventures out there.   The two Tama stories actually constitute one big novel.  How does it stack up?   Not bad.  I'd rank it roughly along the levels of Farley's Radio Man series, sort of sub-Burroughs.    There are some pretty strange choices going on.

Tama of the Light Country opens up with breathless news reports of a mysterious attack on a girls' summer camp, during which a grey-skinned man and a winged woman are killed.  In addition to being peculiar in and of themselves, their bodies are unaccountably light, weighing about two thirds of what they ought to.

From there, it segues into the discovery of a manuscript written by the "sort of hero" (sort of hero in that he disappears for long portions of both stories), Guy Palisse.   Palisse it turns out had built himself a moon rocket ten years before and disappeared.   Then with a kind of unerring sense of direction that puts one in mind of Carson of Venus, he wound up on Mercury.  His spaceship shattered, he just sort of relaxed and fit in on Mercury's light country, going native.

Anyway, he sort of strikes a friendship with Tama, flying virgin, and her brother Toh.   It seems that Tama's a bit of a feminist or suffragette.   See, on Mercury, the women have wings and can fly, and the men can't.  So, the men, being bastards, mutilate a woman's wings upon marriage, so she can't fly anymore.   A married flying woman and any children she has are automatically put to death.

Tama's agitating against this brutal order.   However, the results are counterproductive.   The government passes a law providing for the automatic mutilation of girls upon turning sixteen.   This incites a revolt of the winged virgins, who gather up and fly off.   Guy comes along, because, you know, they need a man to lead them.  They're feminist winged beauties... but not that feminist.

Anyway, the bad guys, led by the traitorous Roc comes after them....   And then for no good reason, the story takes a major swerve, as the Mercurian louts decide it would be better to go to Earth and kidnap girls who were wingless from the start...   After that, the story shifts to Earth and Space, and not too much of the story, overall, actually seems to happen on Mercury.

And, oh yeah, there's Roc's dad, Croat, this seven foot giant dressed in animal skins, who got exiled years before for trying to take over the Light Country, and who has taken over the Cold Country and figured out how to build ray guns and spaceships....  In a society where lights are provided by animal fat lamps, and the sling is a sophisticated weapon.  Roc's dad is quite a villain, but oddly, it seems that most of his major villainy is years before.

The second book, Tama: Princess of Mercury (she may not actually be technically a Princess, she's more a Joan of Arc, or perhaps a Nellie McClung), picks up the pace quite a bit.   Starting on Earth where the previous book left off, there's altogether too much time spent on hugger muggery.  Eventually, good people fall into bad hands, more good people come to the rescue and then everyone takes off into space for a long chase where they keep having Jerry Springer moments until finally they get to Mercury.

Guy Palisse?  He barely shows up.   Instead, points of view get fractured among two or three earthmen, and a handful of characters, including Tama dominate the scenery.  It’s pretty much impossible to pick out a clear hero or narrative thread.  It's just people having things happen to them.

That said, when it gets to Mercury it really heats up.   There's some fairly brutal and chilling scenes of the Water City being attacked and laid waste by an invasion from the Cold Country.   This gives way to a full scale war. Luckily, everyone lives happily ever after.

Look, both novels are available as ebooks, the price is pretty reasonable.   If you're interested, give it a chance, read it for yourself.

So, what's Cummings Mercury like?   Some good, some bad.   Cummings Mercury has a breathable atmosphere, obviously.   As the Earthmen approach it from space, they see it covered by a thick greenish cloud cover that obscures the surface.  Guy Palasse, writes:

"There is generally a pall of gray cloud masses overhead. But occasionally there are the black storms, and then we have an inky night such as there sometimes is on Earth. Fearsome things, these black storms. They last for two or three Earth days--sometimes longer. I shall have much to say of one of them--it has played so large a part in the events which have brought us now into these dire straits."

This kind of makes sense.   If there was an atmosphere and any amount of water, sheer heat on the hot side would be pumping tons of water vapour into the upper atmosphere and creating a thick cloud cover that would reflect away a lot of sunlight, moderating the temperature. Otherwise, Mercury becomes an oven, no matter where you are.

The last thing Mercury needs is a greenhouse effect, it's got to reflect away as much sunlight as possible.  Ray Cummings Mercury is probably a much much brighter star in the sky than our Mercury.

An atmosphere which is heated on the dayside would circulate around to the nightside, warming that.  Cool air from the night side would circulate to the dayside, leaving a bearable climate.   Instead of 900 degree differences between day and night, it might only be a hundred or two degrees between hottest part of dayside and coldest part of nightside.

Of course, there's a problem.   As clouds and water vapour circulate to the dark side, they'd cool, condense and water would fall out as rain or snow, and then it would fall out of circulation.  Eventually, all the water would wind up on the dark side trapped in ice and snow, which would end the cloud covers, and that would be it.   The planet would start to heat up and turn into an oven.   Of course, this would eventually melt and release water vapour from the dark side, but you know, it doesn’t sound like a very stable cycle...  Think yo yo with sledgehammers.

Still, Cummings is going in the right direction when he thinks heavy cloud covers, and very volatile weather.

"Time seems different here. I have lost count of Earth days, months and years. There are no days and nights in the Light Country. It is in a zone of half-light-always the same brightness, except for the weather."

The Twilight Zone should be a long narrow strip circling the planet, with the fire country on the one side and cold country on the other.   Sadly, we don't get that impression in any clear sense.  There's a light country, and adjacent to it is the fire country and cold country, but we get no sense of the light countries geography.   Instead of a ribbon, possibly a narrow ribbon, it's just a sort of blob of territory.  We get no clear sense of what should be peculiar dimensions.   Still, its clearly a permanent sort of place.

"I must be brief. There seems so much to tell you! I can give you so inadequate a picture. Around the Hill City is a barren waste of metallic coppery hills, jagged spires, canyons like gashes filed by some Titan metalworker in mountains of metal. Bleak landscape. For miles there is no blade of vegetation; no soil, save a metallic dust, worn by the rain and wind. Pools of water from the rain lie glistening in all the hollows. A fantastic landscape. It looks like nothing of Earth or the Moon."

"This is the Light Country, the best region of Mercury. It is not quite so forbidding. There are oases-valleys where rock which was not metal has been worn into a soil. In them, with the abundant rainfall and the heavy humid beat, there is always luxuriant tropical vegetation, great spindly shafts of trees, flimsy and porous, and air vines with giant spreading leaves and vivid, exotic flowers."

This is some of the best of it.  As we've noted, Mercury is very dense with a huge Iron core, occupying 42% of the internal volume.  Indications are that the metal content of the crust is very high.   The world is one of sunblasted baked rock, exposed to ferocious temperature extremes.   So metallic coppery hills, jagged spires, canyons like gashes, forbidding rock, fierce ridges and immense boulders and rubble is actually very close to what Mercury is really like.

Setting aside all that stuff about soil, rain, and vegetation.   But given the luxuriousness of Earth, it's strangely affecting and appealing to see a world where life and plants are only an occasional thing, and it's mostly all naked rock.   It's reminiscent perhaps of some of the weirder landscapes, particularly in the Canadian Shield or around Drumheller, where the landscape is twisted, surging rock.  It's likely that Cummings actually wandered through some territory like this...   One thing is for sure, as used as we are to a world covered in vegetation, it's downright unnerving.

We don't see too much of Mercury's civilization, or flora or fauna.   Certainly nothing of the vivid detail that Burroughs used to make his world come alive.

The Light Country has six principle cities, of whom only two, Hill City and Water City are named.  It appears that the Cities are all under some sort of central government, but the nature and operation of that government is not all that clear.   The cities of the Light Country are pretty low tech.   Light is supplied by candles or lamps burning animal fat.   Weapons generally consist of knives and slings that launch feathered arrows.   The most sophisticated weapon is a small catapult.   Basically, what we’re looking at is a bronze or iron age society.

But at the same time, there is electricity and some electrical weapons and tools.   It seems that Mercury once sported a much more advanced civilization, one that, with declining population, they could not sustain.   So they still have records, and perhaps remnants of death rays, handheld lasers and even interplanetary spaceships.   The Light Country civilization preserves much of this knowledge, but doesn't seem to do much with it.

Ironically, Hill City is not on a hill, but located in a large crater.

In such a valley the capitol, the Hill City, was built. It occupies the bottom and the inner sides of a huge bowl-like depression in the great metal plateau surrounding it. The level floor is perhaps five miles across.

"The level streets, tree-lined, are really roads rather than streets. There is no congestion of houses. Fertile fields lie around the homes, each tilled by its controller. The low houses are built of the prevalent copper. There are gardens, trees, and always a profusion of brilliant flowers."

"The outskirts of the City lie upon the surrounding inner slopes of the bowl. Boulevards, like concentric rings, circle the fifteen-mile area. And there are other streets running like spokes of a wheel from the valley floor up to the thousand-foot height of the upper circular rim. An artificial reservoir-lake is beside the palace, in the center of the valley floor."

Large, but not colossal.  This is a run of the mill big ass crater, rather than a structure like the Caloris basin.   It's nice that he never actually says it's a crater, but that's obviously what it is.

Interestingly, the only other city we see, Water City, is also located in a huge crater.  That one is much wetter, with houses on stilts, water strees, marshes and terraced agriculture.   Water City is actually described more vividly and beautifully than Hill City.

We can pretty much assume that the other cities are also occupying big crater basins which have become fertile through trapping dust and water.

As for the people:

"Such is the Hill City. Its people, inhabitants of this Light Country zone, are generally smaller than Earth people. The men average perhaps five feet. They are heavy-set, squat fellows, with wide shoulders and thick chests, but of lesser strength than an Earthman,"

Their skins are ruddy or white, their hair is jet black.  No blondes in this part of outer space.  Their facial features, when described, resemble American Indians.   Their bodies, we find out early on, are adapted to be light.  Even on Earth, they weigh only about two thirds of what they should.

Women are smaller, approximately 4'6" on average, with slender frames.   Oh, and they've got horking huge wings, with ten foot spans.  They've got feathers and everything.   The wings come in different colours.

Most Mercurians are kind of runty.  Although heavily built their strength is commensurate with their planet, so that humans are powerhouses.   This kind of makes me wonder if they know what they’d be getting into with Earth girls, who would on the whole be larger and stronger than them.   Not all Mercurians are short though, there are two freakishly huge giants among them...  The villain Croat, from the Light Country is almost seven feet tall, while the evil Dorrek of Cold Country is about six and a half feet.

The Cold Country, adjacent to the Light Country, is occupied by humans as well.   These people are even heavier set, flabby looking in appearance, with gray skin.  The women are gray skinned and gray winged.   Possibly the flabby appearance comes from fat storage through harsh times.

There's a passing reference to the Cold Country having a government, but they dress in animal skins and act like cavemen.   Seriously, these Fred Flintstone types.   There’s not a lot of indication of technology.

Oddly, under the leadership of the Light Country renegade Croat, they manage to build a bunch of death rays and a couple of spaceships...   But strangely, they aren’t able to pilot their own spaceships and they can’t operate their death rays very well.   That, together with their general primitiveness, suggests perhaps that they didn’t so much build these toys as excavate them from some long lost cache.   But hey, that's me thinking out loud.

Given that the Cold Country is either on the dark side, or the darker side of the twilight zone, you have to wonder what they're eating.   It's not like there's going to be a lot of heavy photosynthesis going on, or spring or anything such.   But there does seem to be a lot of animals around, because they're wearing furs.   Go figure.

The cold country is an area of savage geography, when the war comes to it, the reports are of steep mountains, cliffs, and deep valleys and chasms.   Mercury is a world of stark empty jagged rock, and the Cold Country is starker and fiercer, it makes the Light Country look like Disneyland.

We only have a few references to the Fire Country, mostly that its inhabited by undescribed savages.  Presumably human with winged females.   It might be that Cummings pseudo-prequel novel, The Fire People has more information for us, but unfortunately, it's not available.

There are animals on Mercury, the Cold Country folk, as I noted, are wearing someone's furs.   But there is only one animal, or other form of life described, and this isn’t well described.   The creature is the Brue.  What is the Brue?

Well, they're consistently referred to as giant insects, about ten feet long, basically oblong in shape.   When they lift up their heads high, they're as tall as a human.   The description indicates an armoured, or shelled, jointed body, and a "myriad" of short, hairy, spindly legs.   One reference suggests a forked tail.

But there are peculiarities.   The Brue has arms longer than a human.   In an early scene, one sweeps down on Guy Palasse holding its long arms above its head.   It has a round head with a bulging forehead, a pair of deep set eyes, a wide mouth with a tongue...  It's consistently described as having a semi-human, or humanlike face which is capable of expression.  They also scream and howl with pain like a regular animal.  This is peculiar, since insects don't actually have faces in the same way we do, the description is more reminiscent of a humanoid, or vertebrate than an arthropod.

It does have antenna, although the descriptions of these shift.   At one point they quiver, at another, they're jointed like miniature arms, at another they're as sinuous as an octopus' tentacles.

The Brue appear to be at least semi-intelligent.   They're domesticated and used as beasts of burden and war in the Cold Country and the Light Country.   In one early scene, one appears to listen to Guy Palisse and then set a trap for him.

Apart from scattered and partial descriptions though, they’re simply monsters.  We don't know if they have male or female, if they're colonial animals, do they give live births, lay eggs, have litters, what do they eat, how smart are they, can they speak?   Who knows.

---

Re-Imagining a Fantasy Mercury

---

We've had a lot of fun with Mapping Mars and Unraveling Amtor, basically reconciling the works of Burroughs, Kline and other writers' fictional Mars and Venus with the topography of the real planets.

Can it be done here?   Not directly.  We've only got imagery for 48% of Mercury's surface, and we don't have anything like decent topography. On the other hand, the fictional geography of Mercury allows for very limited mapping.

But it might be fun to try and lay the fictional Mercuries onto the real one to see how they work.  Or to try and squeeze Cummings Mercury into the same universe as Burroughs Barsoom.

The first thing that we allow for is the Light Country.   Mercury doesn't have the sort of world spanning "twilight" zone that Cummings and other fiction writers imagined.   But it does have permanent or near permanent twilight zones at its poles.

So in fact, the permanent light country or countries would be the two polar areas of Mercury.   This is actually nice.  It sets up a neatly Burroughsian premise of two rival but identical realms, the north and south polar light countries, potentially at war.
Given the lack of detail, there's nothing to stop us from assigning Cummings Light Country and its six cities to one of the polar regions.   The cloud cover is apparently heavy, scattering light around.  The only evidence might be a slow procession of shadows, and frankly, Guy doesn't strike me as all that observant.

There is even one slight bit of evidence to suggest that instead of being somewhere on the rim, that they're up at the pole....   Hill City.   Obviously, it's not on a hill, it's in a crater valley.   So where does it get its name?   Possibly from a nearby Hill of Eternal Light.

Y'see, the pole on Mercury doesn't tilt.  Which means that a deep canyon or crater at the pole may be eternally in shadow.   By the same token, a tall enough hill may actually poke above the gentle curvature of the pole, and in that case, its peak would always be exposed to the sun...  a peak of eternal light.   So perhaps this is the Hill that gives Hill City its name.

How big is the Light Country?   Mercury's surface area is about thirty million square miles, or 3/5ths of Earth's total land area.   That's not too bad.   The stable polar areas may represent perhaps five to ten percent of the planet's territory apiece, so perhaps one and a half to three million square miles?   At the upper end, the Light Country would be about the size of Australia, at the lower end, Argentina.   These are pretty good sized areas.   Even if we halved the lower range, we'd still wind up with a minimum size for the Light Country of Alaska, Texas or France. Respectable.

At first, superficially, we've got a problem with the Cold Country and Fire Country.   After all, these are stable areas adjacent to the light country.  How do we explain that?

Actually, it works better this way.   Remember how I was wondering how the hell the Cold Country managed to sustain an ecology?   What the heck were the Cold Country folk eating?   Whose furs were they getting?  And what the animals providing those furs were eating?

On Earth, we've got credible winter ecologies, with Polar Bears, Musk Ox and all sorts of critters.  But the thing is, Winter is dead time.  There's not a lot of growth.  In the cold country, it's not only cold, but presumably, they've got no photosynthesis going on.  The only way that the cold country ecology can be sustained is if they get into the light once in a while.

So the Cold Country and the Fire Country are in the subarctic areas of the poles.   They both sustain viable ecologies, because the slow rotation of the planet gives the Cold Country a shot at summer and photosynthesis, and the Fire Country a shot at water in winter.

But still, doesn't that defeat the whole point.   If the sub-polar areas are rotating, then doesn't the Cold Country become Fire Country and vice versa?

Take another look at the geography of the Cold Country.  Cummings describes steep mountains and deep chasms and canyons.   This means lots of sheltered shadow areas where ice and snow will collect and be slow to melt.   Even where the Cold Country is directly in front of the sun, the mountain shadows, and chasms and valleys will be cold and will lose their snow and ice only gradually.   By the time it starts to get dry, its already turning back to the night side.

We don't know the geography of the Fire Country, but we can assume that it's most likely a flat plain or open country, without chasms or mountains to provide shadows.   It gets a lot hotter.  During the night, it probably gets cold and snow covered, but come the light, it heats up and dries out pretty fast.

The sub-polar tribal areas probably act as a barrier, confining the people of the light country to their narrow polar area.   They may not have much, if any, idea that an opposite pole and second light country exists.

Indeed, this may explain the discrepancies with Cummings earlier 1922 Fire Country novel.   It's just a completely different population on Mercury, isolated from Tama's.

The implication, is that Cummings novel touches on only a relatively small section of Mercury.  There's an entire other Light Country at the other pole, and there’s a truly strange land of a sweeping twilight zone that continually marches as the planet rotates and revolves...

---

An Undiscovered Country - Rotisserie Lands

---

Now, what about the place in between, the habitable twilight zone that is away from the polar regions?   Unfortunately, in contrast to earlier expectations, this is not a stable place.   Since the planet is rotating at a 3/2 ratio, what this means is that the whole place is on a slow rotisserie.   The twilight zone is continuously moving, forever advancing into flame and retreating into ice.

Which would make it a hard place to live.   Definitely.  But perhaps not completely unbearable.  What we might find are plants and animals adapted to surviving in this harsh environment.

Assuming that the thick atmosphere scatters light and warmth, the Twilight zone is probably a band on either side of the planet.   We can't say how thick it is.   In an airless vacuum, it may be a knife edge kind of thing, the "twilight zone" period might be an instant, a minute, an hour.  With the protection of an atmosphere, it might be as much as five or ten days on either side, leaving eighteen or twenty two days of blazing sun, and eighteen or twenty two days of stifling darkness, in a fifty five day rotation.

(Actually, the time scale is a little bit more favourable than that.   Think about it.   Earth has a relatively short day, 24 hours, and a very long year, 365 days.   So, in the course of a day, the planet doesn't move very far along its orbit.   So we have no trouble calculating both day and year and keeping them separate.   But remember that Mercury is rotating very slowly and revolving very fast.  In the course of a typical Mercurian "day" of 55 days, the planet has traveled two thirds of the way around the sun, which means that the sun is actually in a different place relative to the planet.   So that sun seems to be going down a lot more slowly than you would think.  Indeed, it might take a lot longer than 55 or even 88 days for the sun to vanish completely below the horizon, or for the ‘twilight’ zone to sweep completely around the planet.   Mercury probably has a "day/night" cycle which is quite different from Earth's simple process, and is based in the interaction between the Mercurian day and year.  For anyone who is interested in doing the mathematics of Mercury's "day/night" cycle, welcome to it.  I freely admit that it's beyond my abilities or inclination.)

The key however, to a longer day/night cycle than simply the rotation period, is that the twilight period would be much longer as well.   Of course, the "hot day" and "cold night" would be equally longer, but them's the breaks.

Interestingly, in Tama of the Light Country, our sort of hero Guy mentions that plants in the light country grow incredibly fast.   You can plant a seed and have a harvest crop in a dozen day spans or so.   Now, this doesn't make a lot of sense in an area of permanent light.  But what it does suggest is that the plant life of Mercury is adapted to very short growing seasons.  Growing seasons of only a dozen days or so....  The sort of growing season you'd expect on a constantly moving twilight zone, where any particular spot will only be in twilight for a dozen days or so.

We would probably see two kinds of plants.   Those who sprout and die very quickly, in the two"‘twilight" periods on either side of the planet, and whose seeds are adapted to surviving the long fire of day and the ice of protracted night.  Or we'd see plants which put down deep root systems to survive the harsh days and nights, and marshall their energies for intense periods of growth and metabolic activity in the twilight zones.

So, what are animals to do with this?   Well, they've got three options.   One is to dig way deep and hibernate for both the hot day and cold night, coming out during the two twilight phases for a desperate flurry of feeding and mating, to build up fat for the hot/cold spells.

Another approach is to go completely underground, living like rats or moles, digging tunnels, and feeding off the root systems of plants who manage to endure the hot/cold cycle.

The third approach is to just stay in the twilight zone, moving with it, so as to permanently remain in an area that is hospitable.   It would be a permanent life long migration, always a step away from a blazing inferno or ferocious icefields.

Could it be done?   Possibly.   The circumference of Mercury at its equator is 9525 miles.   So assuming a 55 day rotation, you'd need to travel about 173 miles a day to stay in the same place.    That's a hell of a clip.   But there area couple of things to think about.

Of course, the revolution period probably slows down the "day/night" cycle.   So in fact, you might only need to travel 80 or 120 miles a day to stay in the twilight zone.   And that's only at the equator.  The further up or down the latitudes you go, the more the circumference shortens and so you might go as low as 40 or 60 miles a day.

That's pretty hard slogging.  Buffalo, Caribou, Eels, Salmon, Geese and Butterflies travel immense distances of thousands of miles during the course of a year, so we know it can be done.   If there are big animals on Mercury, they're probably equivalent to Bison or other heavy duty travellers.

But conceive of it in human terms.  An average human walks about two miles an hour.   Lets say power walking at five miles an hour.   Let's say our average human is spending twelve hours a day migrating in the twilight zone, sleeping eight, and reserving the other four for every other human activity, from eating to making love to manufacturing tools and implements.

Well at two miles an hour, our average human will burn through 24 miles a day, which means that before too long, he's an ice cube or a fricasee.   Alternately at five miles an hour, you're up to 60 miles a day.   Which is pretty good, but unless you’re in upper latitudes, you're still fried or frozen.

So, how to get around this?   Well, the bottom line is that critters are going to have to be travelling pretty steadily somewhere between eight and fifteen miles an hour at the equator, just to be able to keep up.   Since full gallop, or stampede speed for most Earth herbivores is about 30 to 35 miles an hour, we can tell that this involves some pretty steady power movement.

The only way humans would be able to keep up is if they were riding domesticated or semi-domesticated animals.

Or actually, there's another way for humans or other animals to do it:   Fly.

---

The Origins of Winged Women

---

Think about it.   The temperature extremes between day and night are going to produce some pretty ferocious atmospheric movements.    On the day side, the atmosphere is heated up and expands dramatically, spilling over into the night side where it cools rapidly, emptying its loads of moisture, and eventually seeping back over the twilight zone into the day side where it heats up again.   The upper levels of the atmosphere would be pretty hot gases moving rapidly towards the night.  The lower levels would be cooled air moving towards the day.   You'd get steady and consistent winds, and absolutely ferocious thermals.

Well, we know from Albatross and Vultures that you can make a good living as a bird by riding the thermals.   Indeed, you can get some pretty damned big birds up in the air for long periods of time riding thermals. It's a great way to see the world.

So perhaps this partially explains the winged humans of Mercury.   Certainly the gravity and the thermals work.   As Cummings explains, the average Mercurian girl is about 4'6" and lightly built.  In the lighter gravity of Mercury.   Normally, say at 4'6" a girl would come in at about 100 lbs say... But Mercurians are adapted to be even lighter.   A Mercurian girl on Earth weighs about 65 lbs.  Which means that in Mercury’s gravity, she weighs only about twenty five or thirty pounds, and has a ten foot or better wingspan.

Well, the forty pounds is the hard upper limit of what a bird could get on Earth and still manage to fly, and a ten foot wingspan is about right, or perhaps minimum for a weight like that (I would assume that the wings of the Mercurian women have far more surface area or lifting surface to them, being broader, than the wings of the big terrestrial birds).   And there's those amazing thermals to consider.  Once a Mercurian woman gets up into the air, she may not have to expend a lot of energy in order to stay up there.

Perhaps this is the real reason Mercurian women are winged?   So that they can fly, and stay perpetually in the twilight zone, continually migrating against the slow rotation of the planet.  We can imagine an entire nomadic society of women.

Of course, that suggests a "materials poor" society.   Nomads have to travel light, obviously, they can't carry too much.   Weight is particularly a premium when you're flying.   On the other hand, since Mercurian winged women will be circling the planet and coming back to the same places at least three or four times in an earth year, perhaps there is an opportunity to cache materials - to create temples, silos, fortifications, houses, storage depots, etc.

Tough luck for the men though, since they have no wings.   What's their strategy.  And how does it work in a society where one sex is continually circumnavigating the planet and the other is....  Screwed?

Well, can we actually say that men are flightless in the moving Twilight Zone?   Perhaps they are winged after all.

Okay, there's no evidence of this in the Tama stories.  But it does make a certain amount of sense.  After all, the stable polar regions are the only places on the planet where flightless men would have a competitive advantage.   With a stable environment without the need to continually migrate, flight would not be as desperately necessary.   Men could grow heavier and stronger, could accumulate more resources.

Indeed, what we see on our world is that birds who wind up on safe Islands without predators, where conditions allow them to grow big and strong, often become flightless.  Flying birds persist, of course, but, the big flightless birds regularly emerge.

So perhaps in the Light Country, what we're merely seeing is a local phenomenon, flightless males in an environment that allows them to survive and dominate.   There's evidence of a ferocious eugenic drive at work.   Women are relentlessly deprived of the power of flight upon marriage, enforcing male domination.   Not only is a married woman with intact wings automatically killed, but her children are killed as well.  One would assume a winged male child or adult would be killed on sight.  The minute the Mercurians figure they can get their hands on wingless women, they’re jumping into a spaceship.

There is an extremely intense cultural drive there which seems mysterious.  Generally you only have to put a lot of work into something if you’re swimming upstream...  Going against the natural flow.   If we had a stable situation of flightless men and winged women would it really be so pernicious?   Or is it pernicious and violent because the culture is enforcing something that is neither stable nor natural?

But still, if flightless men are a local phenomena, then why are the women of the Light Country and its bordering lands still winged?   Perhaps it’s simply that the avian genes that allow for wings and features bind to the X chromosome somehow.   Two X’s guarantee wings, and a mutation in the Y chromosome suppresses wings.   Simple genetic fluke.

Or perhaps the evolutionary or adaptive pressures on women in the Light Country are different from that of men, and the selection of wings is sexual dimorphism, like beardlessness and breasts on women.   Wings, however, are extremely complex ambitious structures, in comparison to breasts or beards, so it would be surprising not to see at least some vestigial wing structure.   The lightness of male bodies suggests that both sexes possess at least some of the adaptations to support winged flight.

Men become larger, heavier and stronger at the price of mobility, they become more effective hunters able to bring more strength to take bigger game.   Women retain their mobility, perhaps to facilitate their ability to mate freely, perhaps because that mobility gives them more opportunities for gathering.   So perhaps it’s a hunter/gatherer dichotomy, with the two sexes embracing different lifestyles.

This sort of thing is not unknown in nature.   Consider the Orangutangs.   Male Orangutangs are twice the size of female Orangutangs.   What this means is that the male orangutangs are confined to the heavier branches and trunks which can bear their weight.   Meanwhile, the lighter female orangutangs can travel freely across much lighter branches.   The two sexes are literally inhabiting different forests, with female orangutangs being far more mobile and having far more access to food for themselves and their young.

But of course, the same logic might apply for the twilight zones.   Perhaps the Men of the twilight zones are winged.   In which case, they'd have to be as good fliers as women, no more and no less...  Because the major adaptive driver for flight is the need to stay in that moving twilight.

Or perhaps they are not, in which case, flightless men are forced to a radically different lifestyle.   The women can endlessly fly into to the twilight zone as it moves around the planet.

The Men have two choices.  They can become equestrian nomads, trying to find a good riding beast, and simply follow the hypothetical migrating herds on the equivalent of horseback...   A hit or miss proposition, since we don't know if there's a suitable species.

Or they are pretty much stuck in their piece of territory.   Which means that they have two short hunting/farming/gathering seasons, and then they're stuck sitting out weeks of hot daylight, or cold winter in insulated cabins.   Or villages.

This would make for radically different male and female cultures.   The male cultures would be territorial to an extreme degree, perhaps competitive and aggressive, particularly considering the narrow windows they have for gathering food and resources.   A man doesn't have the time to wait for the next round, if a rival scoops him on a bush full of berries.  There may not be time enough to get to the next bush, there may not be another bush full of berries in walking distance, or before the fire or the cold comes.   So we may see ferocious rivalry and violent territoriality, both within and between villages.   There's probably going to be high tensions over entitlements and property.  At the same time, they're going to be a highly time based culture.  After all, the window on gathering food and materials is narrow, what foods or materials may be most effectively gathered at what time is a very important question.   There may be a highly specific sequence of gathering or hunting activities to utilize the best timing of resources.   Even when trapped during the cold season or hot season, the males are probably still busy, preparing, mending, digging, preserving or building their shelter, tools, goods and clothing for the next twilight period.

In contrast, all the women have to do is stay in the twilight zone, and their greater mobility means that they’re able to access more resources more easily.   They're not as concerned with territory, since their territories are vaster.  They're not as concerned with possession, since their territories overlap.  And they're not as concerned with time or timing.

So how do flightless men and winged women relate, when their lifestyles are so different?   Women may have the role of traders, moving small goods or key resources from one area to another, and this may be critical for men.    In addition, men may put a lot of time and energy, not just into surviving, but into making their areas attractive to women....  Having a nice house, a garden, a beautiful flower bed, all for the purpose of getting laid by a winged babe.

Of course, if the populations grow too heavy, then there's not enough free territory for women, and they start to compete with the hyperterritorial men for vital resources.  In that case, you might well see men coming to regard the flying women as something like locusts.   And the women might regard the men's territoriality as a sort of theft, fencing off what should be free.

And there are interesting issues in population distribution.   Men are distributed uniformly across the surface of the planet in small isolated territories.   While women are all in the twilight zones.  Assuming even populations overall, this would mean that women would far outnumber the men in any particular twilight zone section.   Or if we assume that the population of men and women in a twilight zone is even, then the total population of men would far outnumber women.  Each of these demographics might have different effects on culture and the relations between the sexes.

Looking at the part of Mercury that Cummings writes about, we seem to have both circumstances in play.   In the Light Country, the population of males and females appears to be about equal, or more equal than holds in the Cold Country.

In the Cold Country, the males outnumber females by ten to one.   The peculiar disproportion of males to females in Cold Country is difficult to explain?   Do females have a vastly higher mortality rate?  Or is there some genetic glitch which just tends to produce more males?  The explanation likely leans to different mortality rates, or we'd expect to see a similar genetic glitch in the Light Country.

In any event, we can’t do more than sketch out what might be some quite interesting cultural issues.

---

Angels, Angans and Zarkoons, Oh My

---

If we play the game of "connect" the worlds, there's very little clear indication of anything to directly connect Cummings Mercury with Burroughs Barsoom or Amtor, or Kline's Mars or Venus.   There don't seem to be any little allusions, nor any intriguing linguistic coincidences.

But it's worth noting that Cummings' winged and feathered women have their counterparts in other other winged and feathered races, including Kline's Bird People of Venus (or an alternate Earth), or Burroughs' Angans of Venus, Griffith's Venusians, and Carter's Angans.   There might even be an overlap to Burroughs Weiroos whose sexual politics are completely opposite.   Although Burroughs never goes there, Leigh Brackett writes of bird winged Martian humans or humanoids.

So it would seem that like Pseudo-Tharks, Bird-Winged Humanoids are widely distributed through the Solar System, although only on Mercury and parts of Venus do they form a significant population.

Unfortunately, although we can trace all the Pseudo-Tharks back to Barsoom and argue for their origins and diversification, the Bird Winged Humanoids are tougher.   Where do they originally come from?   Mercury?

It appears that the Bird people of Mercury once upon a time had spaceships, since they rebuild or excavate them again in the Tama stories.   So it's possible that the Mercurians sailed to other worlds and established colonies that mutated in different ways.

Or it's possible that the spaceship technology was not Mercurian at all.   Consider that Mercury, particularly the habitable portions stable portions of Mercury, is a very small world.  Would it have had the resources and population to eventually build a technological infrastructure capable of spaceships?

Or perhaps more likely, the spaceships came from somewhere else.   In which case, the Mercurians are not native to their world, but transplanted there.   Somewhere around here, I've argued that Barsoom's Orovars must have gone into space, at least to a limited extent.   See the Secret of Thuria.   And, on the basis of Otis Adelbert Kline's Martian and Moon novels, it's confirmed that a white race of Martians did indeed go into space and have a war with another local spacefaring race, the Ma Gongi.    So, working from there, I'd argue that the pseudo-tharks we see around the solar system, together with little anomalies like Lin Carter's Othodes (who seem near identical to Barsoomian calots), and an atypical six-limbed Venusian Predator that Carson encounters (which also seems Barsoomian), have been transported or relocated by the Barsoomian Orovars.

So, going by that, I'd suggest that the Mercurians have been transplanted to their world from somewhere else, perhaps Venus, by the Orovars.   Then, following the collapse of Orovar civlization, the conditions were such that on Mercury, the human races died off, leaving only the bird people.

But there’s another problem.  The Mercurians are the most fully human of the bird races.   Why is this?  There's no clear answer.   Perhaps this was due to tinkering or selective breeding by the Orovars in a population small and inbred enough that it would preserve the look.   Perhaps the Mercurians represent the "base stock" of Bird-people and the other races represent departures or mutations.   Possibly the Bird-races are fundamentally human, and have simply been artificially or accidentally modified.   I might have to wait for more evidence before putting forth a persuasive theory.

However, there is one somewhat shaky piece of evidence I can offer for the Orovar Origins theory:   The Brue as a Pseudo-Thark.

Actually, the identification of the Brue as a member of the Thark races is a pretty iffy one.  The Brue is consistently described as an insect.   But on the other hand, Larry Niven in Rainbow Mars identifies the Green Men as being descended from Insects or Arthropods, and several of the other Pseudo-Tharks, particularly Farley's Formians and Kline's Sabits, both on Venus, are also described as giant insects.   So the notion that the creatures may be seen as insectlike, particularly if the humans have never seen anything else like them, is not necessarily a barrier.

The size of the Brue seems to be in line with the Green Men of Barsoom, the Sabits, Formians, and others.   In ground posture, roughly ten feet long, which meant that if they were standing upright on their two hind legs, they'd be about as tall as Green Men.

On the other hand, there are differences.    The Thark races are all six limbed.   The Brue are described as having a "myriad" of short hairy legs, and at least one pair of arms.  Or perhaps the front legs double as arms. Well, that's a minimum of four to six "legs."  Is that a myriad?   Perhaps because they move so fast it might follow. Cummings never gives us an accurate count of limbs, so it could be four or six, or they could be veritable centipedes.   There's also a reference in one scene to a forked tail, which is hard to explain, except perhaps as sloppiness in the heat of the moment.   Unlike the upright Tharks, but like the Sabits and Formians, the Brue seem to prefer to go on all fours, or sixes.

Of course, Barsoom is full of multi-limbed predators.   Banths, Calots, Ulsios, Apts, some of which have eight or ten legs.  So, conceivably, the Brue could be more closely related to one of those.   Except... that the Brue has a face, a semi-human face, with deep set eyes, an expressive mouth, and a forehead.   And more than that, the Brue appears to be intelligent or semi-intelligent.

To be truthful, I’m pretty sure that Cummings did not intend the Brue to be Tharks or that he was inspired by Tharks in any way.  The best that we can say on that side of the coin is that he was almost certainly had read A Princess of Mars and its sequels, and that there was some conscious or unconscious copying of Burroughs, as in his titles.

But on the other hand, his description of the Brue is scattershot and vague enough that if we want to, we can assign it to the category of pseudo-tharks.   It may not be an entirely comfortable fit, but it is a fit.

What this means, however, is that if we accept that the Brue are another Thark offshoot, transplanted from Barsoom, then this means that the most likely way they got there was by transportation through the Orovars. And in turn, this raises the likelihood that the winged Mercurians and their civilization were also transplanted by the Orovars as well.   The Mercurians may originally be from Venus, and their culture may derive in part from the Martians.

Of course, this begs the question as to whether, in Barsoom's universe, Mercury is inhabited at all.   On this score, I’ll let Ras Thavas, from chapter three of Master Mind of Mars, speak:

"From what I know of Earth and from what I have seen of you, I am convinced that there is no mind upon your planet that may even faintly approximate in power that which I have developed during a thousand years of active study and research. Rasoom (Mercury) or Cosoom (Venus) may possibly support intelligences equal to or even greater than mine. While we have made some study of their thought waves, our instruments are not yet sufficiently developed to more than suggest that they are of extreme refinement, power and flexibility."

So clearly, in Burroughs Universe, Mercury is an inhabited world.   And if Burroughs has chosen not to fill that world in for us, then I think we can find ourselves justified in accepting Cummings vision as a part of the Barsoom universe.