That's a very large stone.
Most were a bit smaller. The ones in this pic I swiped from a stock photo place were either for small presses, or more likely were the masters.
Printing from stones isn't really stone age. (Although I like that way of putting it. ) It's still done at some art printing places.
I guess a few definitions of sorts to clarify things.
Direct stone lithography - Just what it sounds like, the image is drawn or put down as a transfer to the stone, in a mirror image of what's wanted. Then the stone is wet, inked and a print taken. It's labor intensive and slow, and the stones wear pretty quickly. Somehow it's the method has survived commercially despite being the oldest. It's still used for short runs of art prints. (It can even be done at home with no stones, using crayons, paper, water and an oil based ink. Excellent results are challenging, it usually comes out looking just like it sounds )
Flatbed offset lithography. - The images are put on the stone normally, wet inked and then printed onto a rubber sheet that's on a roller, then printed to the paper. Still pretty labor intensive, but not as much as direct. The stones don't get worn as quickly, and the presses are faster.
There is some proof this method was used for at least some T206s. One particular card with a major defect that could only some from a press like this.
Rotary offset - here's where things get "interesting". With this method a prepared plate is wrapped around a roller. (Usually aluminum) Wet, inked automatically, and then the plate prints to the blanket which prints to the paper. all between rollers.
This is the method that is essentially used for most commercial printing. There was a big change several years ago and current pesses make the plates on the press from digital files. But it was nearly unchanged until well into the 1980's.
For all three, the stone/plate can be made using transfers printed from master stones so that multiple "identical" items can be printed from a larger stone.
Sheet fed- just that, the press is loaded with individual sheets.
Web fed - The press takes in paper from a large roll, and either produces a large printed roll or has an onboard cutter that cuts off individual sheets.
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The following includes some conjecture that is difficult to prove, but can be convincingly argued.
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The interesting parts? Most sources online say the first press of this type was made right around 1910. And was eventually sent to the west coast.
But... Not to any shop associated with ALC.
I have seen references to RS Hoe making a rotary offset press prior to or in 1909.
And from other sources ALC was pretty tight with RS Hoe. They were possibly Hoes biggest customer.
Hoe made some insane stuff for other types of printing. Multiple station typography presses that were web fed for producing newspapers. Multi color presses for newspapers and ads...
1909-1911 falls directly into a time of massive technological change, as all the modern things in lithography were either being invented, or were just getting to be common enough to be known. And RS Hoe was right at the forefront along with a few others.
There are some things that point towards a two color lithographic press being used. And that in turn also seems to indicate a rotary press before the supposed 1911 invention. (Just because even a two color flatbed offset would be a high level of mechanical insanity.) And that... leads to a possibility that it was web fed.
A web fed two color rotary offset press in 1909 or earlier would have been sufficiently advanced in efficiency that anyone sensible would have treated it as a trade secret.
RS Hoe had essentially all the pieces to do that at the time. If it was done for Their largest customer ALC, it's possible they contracted some period of exclusivity.
It's possible, perhaps even probable that ALC and it's affiliated shops printed sheets of different sizes by different methods.
The discussions, often heated we've had since 2007 (Only 2009 ish for me) for a while revolved around paper size and if the cards were done in groups of 12 or groups of 17 (or more)
I think both are probable. The smaller print groups that mostly consist of 12 cards to a group are well established based on experience of guys like Ted, and as iffy as it mays seem, pop reports. Likewise, the groups of 17/34 like the Souther leaguers are also well established.
At this point, I consider both 12 and 17 card groups to be fact.
There are lots of angles to study, like looking very closely to see if the brands with small press runs can be identified as being done separately or if they were done on fronts shared with the more common brands.