I'm still without Internet access at home so I'm posting from my home. I'm probably at least a week or maybe more from posting on stories. Between work demands from before and the power outage I am pretty busy at work.
And if so, this should go in the wiki somewhere, only I can't figure out where. In the regio description?
Turbulences? What is?
It seems to me like we're having two different conversations here. The first is, "Do we let Sheelagh read summa?" To which I respond, if it bothers you so much, have her use the Perfectly Ordinary Mirror -- if we can't use it to allow multiple readers of the same book, then it's primary use is to safeguard the books. Does that solution alleviate your concerns adequately?
The other question, it seems, is "Does the setting have apprentices typically reading from summa?" To which the question is pretty clearly "yes," and I think that your concerns would be valid and perhaps be the reason why quick-copies and all that book trading happen. It also explains why apprentices have such low experience points by the book than if we develop them from scratch. In other words, I think your concern is what creates a market demand among the magi.
I'm not really sure I buy the "susceptible to need" line, though. The way the world setting works, books gather a lot of dust.
"Turbulences" are a new principle introduced in Apprentices...basically, it's like in the comics, where a young mutant's powers manifest randomly and wildly until he learns to control them.
They're detailed on pages 22 through 24.
The original Cygna, since she had Gentle Gift, the first time anyone found out she was gifted was when she had a de facto Turbulence when her covenant was under attack, when she accidentally ReMe'd a bandit and had him attack his cohorts.
On the plus side, they are affected by Aegis of the Hearth, so if we're worried about Turbulence, don't let them participate in the ritual.
Yes, totally.
This strikes me to be a great use of such enchantments. There's probably vis to be made by crafting some for these magi who want their apprentices to progress quickly, yet do have a medieval mindset about books, that precious ressource.
I'm not so sure that this is firmly entrenched in setting (so if you have a reference, please, provide), but I don't trust my memory, so let's say it does.
Having copies for apprentices, or old, low-level, spare books is fine. But I just don't see the magi letting an apprentice read, and maybe damage, their only book (or their more precious book) on some subject they are susceptible to be wanting to read at some point.
Imagine we have her read from our Creo Summa, and mishandle it, dropping its quality by 3 points. How would the magi react? What if you wanted to study from it 3 seasons, and now find that you need 4? This is what I meant.
Oh, also, most book trade ain't summas. It's tractati, for all those magi who've exhausted their covenant's ressources 
Look at Isen: How is he gonna increase his parma? His Creo? Soon, his Aquam?
I honestly keep forgetting about the Mirror (or maybe it's me subconsciously ignoring it), because to me it just doesn't feel right. It seems a little too "high fantasy" to have a mirror that lets you read a book anywhere in the world.
And that's not even getting into the fact that you have to have an Arcane Connection to the tome before you can use the mirror. And, aside from the library's catalog, I can't think off-hand of an Arcane Connection to a book that doesn't damage it. A piece of the parchment it's written on, a scraping of the ink from the page? Unless you have a Fixed Arcane Connection that you can use, I'm just not seeing it. And I guess that's why I keep not using it.
And I'm still mulling over the statement that "the way the world setting works, books gather a lot of dust." I honestly don't think that's a "world setting" issue as "the way people play their magi" issue, or even a "the way people think they play their magi" thing. For example, on the planner, out of 122 seasons that the magi have that aren't Princeps Duty, 40 are studying from books. So roughly 1/3 studying from books, while most of the rest is lab work (either lab texts or working on items). If this is an issue, how can it be addressed?
How does one turn the Page of the book while reading through the mirror?
It doesn't say (it's based on the spell Eternal Repetition in a Bottomless Pool, from Covenants, p. 101). From the spell description, I don't think the spell actually does anything with the book, physically (it's a Creo Imaginem), all it does is "display the text of a book to which the magus has an Arcane Connection," and you can give the mirror verbal commands to "navigate" the book. So, the book could be still sitting on the shelf, and unless someone has a InVi going, I don't think anyone would know that the book was even being remotely accessed. But you could say "next page," and the spell would display the text from the next page. Or you could have it search for a specific word, phrase, or concept(?), which according to the text are valid commands. Sort of like a hermetic PDF.
I certainly wouldn't object to the income, but it'd boost Viscaria's Hubris through the roof.
And now I'm not sure which part you're objecting to. Look at our own library though.
Out of 122 seasons, 40 are spent studying from our collection of over 25 books, not counting lab texts or the Greek library, which we had to cajole magi into cataloging.
Given that how easily we could remedy this situation with our resources and specialists, I think we should move this conversation in-game. Have Isen get protective about the books and the apprentices, and insist on making working copies for them all, that sort of thing. Especially since we're getting an illuminator in soon.
Given the resources expended in order to make it, this doesn't seem out of genre for me. Granted the original contribution was a spell, not a text (actually, I have MORE of a problem with a spell that lets you issue verbal commands to navigate pages than with a device that does this), but still, with an arcane connection, and lab text, 4 vis, and a season, you can do a lot of things that seem on par with this. And given the number of build points in Bibracte, high fantasy is exactly what we should be seeing.
I'd imagine that Hermetic libraries make a habit of building easily removable arcane connections into their books, the better to safe-keep them.
For example, Covenants, pg 98: "A voucher is a slip of parchment, usually kept within the book, that remains with the library if the book is removed. The voucher acts briefly as an arcane connection to the book, due to the law of contagion."
There's also the Register, or bookmark ribbon, that would be easy to remove and easy enough for a skilled binder to repair as a normal part of his workload.
If "go back to the first mention of frogs" is a legitimate command, it does make one wonder what would happen if you gave it the Library Catalog and said something like, "Open the book which discusses the earliest appearance of Xenophon."
But I'm content with that being another magic item.
What happens to a book when it receives warping?
So, a fair reading of this spell, in light of the warping rules for effects of 6th magnitude and greater suggest that this will inflict 90 warping points (1 per casting) onto the book, which would give it a Warping score of 5, inflicting two minor flaws and gaining a minor virtue...
If you use it all 90 days in a season. A work-season is, what, 78 days (13 weeks in a season, six days a week)?
So, 78 warping points in a season, which gives, as you said, two Minor Flaws and a mystical Minor Virtue after one season of constant use. A second season and the book winds up with a score of 7, and two more Minor Flaws (for a total of four). Season 3, a Warping Score of 9, and two more Minor Flaws (six in all). Season 4, at 312 WP, it has a Warping Score of 10, with an additional Minor Flaw for every additional point in Warping Score. Season 5, it has 390 warping points, a Warping Score of 12 on the dot, and a total of 9 Minor Flaws and a Minor Virtue, and the librarian starts to wonder if books ever go into Final Twilight.
And we were worried about giving the books to apprentices? 
But seriously, this kinda looks like a spell where somebody went "Wouldn't it be cool if...?" and didn't think it through. I wonder if the Grand Council (i.e. the main boards) has any ideas on this?
Well, thing is, they are rather advanced magi, and have mainly exhausted the books for their specialties, so this seems rather reasonnable for me.
For exemple, if it wasn't for Appolodorus Summa and the book I bought, Isen would not be able to read on Creo, Rego and Aquam, which are his 3 main arts. And he'll exhaust these quickly.
For Isen, there are 3 things that had me read less, out of the 20 seasons available when not doing princeps:
- The need to develop the Ice spells I wanted to have, but couldn't before, and which took 6 seasons. These were the most evident, and I am now having a harder time thinking about spells, another thing being that the spells I am considering require me to have a higher lab total (thus, study more).
- The need to "waste" 3 seasons learning ancient greek
- Self-restraining. For exemple, Isen is VERY interested in the "Control" summa, rego being his specialty. But he is not alone, so I try to have him read from it only once per year.
The rest were mostly covenant-related things, like learning Wizard's Communion and the Aegis.
Next time, without the Ice spells and the Greek course, that's potentially 9 seasons for books. That'd put Isen at 15/20 reading seasons, although I'll probably exert some kind of self-restraint, diverting him on other projects.
I know. You're perfectly right. It's just that I feared this would take too much time for me to participate rightly AND that it seemed to me a meta concern, like we were approaching books with a modern frame of mind.
Yes, it is pretty easy to imagine a blanck page dedicated for this purpose (although that's costly), or that, since it's creation, each book have, say, tiny bits of wook kept within them at all times for that purpose.
Interesting things 
Flavorful things. It might distort, take on a more fantastical appearance, have strange effects on it... For exemple, IIRC, you wrote that no one should study "Control" until they are able to cast 2nd magnitude Rego effects. This could mean that the book tends to fly, have things around it go flying, or try to mindcontrol its reader into being obsessed with it, or into leaving it alone. Or maybe it tends to stay shut until forced open by magic.
On the other hand, this is because you spoke of Rego effects, but it could just as well inflame (without burning) when opened. Or smell of roses. Or speak its content aloud.
I like if. Even if they're just distorted and mishappen, even if this is pure fluff and has no mechanical impact, this gives more personnality to books
Agreed. My commentary was more about, if you (as in the characters) are going to use this device on books the players need to be prepared for the consequences of this action. I'm not saying it can't be used[1], I'm just saying that there will be consequences.
[1] The only point where I said the device can't be used is when the book is in use by another person. The device will fail when the book it is targeting is being read by someone else. I'm not going to let two people study from the same book at the same time.
To me, it sounds like one of those devices that someone invented thinking it a great idea. Then when they realized that it damages books they 'sold' it to another covenant. And it keeps going until someone just destroys it.
If you want some creo then make a deal with Korvin. He can get you 16-18 experience for a season.
I was just thinking that a good way to create warped books might be to look at twilight scars. There's a good article in Sub Rosa 10 on that.
These should apply mostly to the book, but could apply to the reader, too
Minor flaws could give "negative" scars, and virtues could give "positive" ones, or something like "Side Effect" virtue at best.
For exemple,
- The book leaves frosty outlines anytime he remains somewhere for a diameter.
- The book always smells musty, stale, and otherwise unpleasant.
- The book looks and feels scaly and fish-like
- The book makes the air hum faintly in any room or within 30 paces.
- The book sports what appears so be scared and purulent human flesh.
- The book is always very warm, exuding steam on cold mornings, surprising people if touched, and quickly melting snow or ice if handled.
- Torches, lanterns, and candles refuse to remain lit within a pace of the book, leaping from their fuel and extinguishing themselves.
- Anyone reading the book feels happy and light-headed
- Anyone reading from the book gains the strange lesions of leprosy for the whole season.
- Anyone reading from the book feels the pain of old wounds reawakening
- Anyone reading from the book loses his hairs (Yikes!!)
Just checking my math.
One oenchantment I want to be able to do with Donar is to teleport him to me, this would fall under a power under the magus's control. It's a Rego Animal, using Leap of Homecoming as a base (there is no Animal teleport spell guidelines). So base is 35, add 4 magnitudes for Arcane Connection Range, and due to his Size, +1 to the target of Individual. So that's a 60th level spell/power right? That's pretty hefty.
Perhaps a spell to find his master. If given a greater power that is up to 50 spell levels. The problem will be that his size will drive down his magic might. Base might is 10 +- size. So Peion, Korvin's weasel, has a size of -3 so he is magic might of 13. I would suggest that you are modest with the dog and add a magic collar later.