Pre-philately transit post to/from Italian states

2) This letter also has a handwritten note inside stating Florence as the sender, as well as a Florence (Firenze) cds of June 1, 1860 and a Geneva arrival mark of June 4, 1860.

But why is there no Sardinian transit stamp like on the earlier cover? I don't know the postal treaties between Sardinia (and other Italian states before reunification) and Switzerland, but were there any changes between 1858 and 1860?

And does that explain the two tax stamps, 40 centisimi in red and 4 (decimes)?

Finally two more letters from the Italian states to France.

1) From Turin, under Piedmont-Sardinia (two-line black postmark of August 19 (1846)) to Marseille, with indistinct arrival mark.







But no Sardinian transit stamp? Or is it because the letter was transported by sea?

Would the postage be 8 centisimi? Doesn't the "4" in the top left have anything to do with it?

2) The second letter initially looked not as a cross-border transit item going from Chamberey to Marseille (both currently within France!). It has a two-line departure postmark from CHAMBEREY of August 17, 1844 and the arrival in Marseille on August 19, 1844, but why then the red double-circle France transit postmark?

In 1844 Chamberey did NOT belong to France, but between 1815 and 1860 to the Grand Duchy of Savoy, i.e. to Sardinian territory. This explains the red inscription in France of Sard(aigne) in Le Pont-de-Beauvoisin.
After that this traveled to Lyon (probably by road, since the TPO sign "Ambulant" or "A" is missing?) and then to Marseille, again by road. Am I correct here on the route? Any comments on the tax?

These prefilatelics are really beautiful, but from the point of view of their analysis, I would not know how to add anything else to what you wrote.

Maybe Roberto ameis33, let's tag him and see if he can add more.

Thanks ameis33! Useful clarifications.
I was erring on a fundamental principle for the application of transit marks: the marks for any territory were applied AFTER the letter has crossed/is entering into the territory, not when it is leaving! So TS mark is applied once the mail crossed from Austria into Sardinia, and the mark for France likewise, when it has entered France at P Beauvoisin!
And thanks for clarifying the two different manuscript marks - coincidence that I just found somewhere else on the small top-left mark usually for the weight (and so more clear!) and the tax mark of a larger size.

I will be soon having more questions for you as have already a small bunch, but of course, as a excited schoolboy would first try to interpret it from my little starting knowledge!

Cheers,
Sumit

Let's follow the first letter.
The letter (with many other cousins) has been first collected in the Milan post office. Here, all the letters were marked with the MILANO postmark, sorted, divided by their destination and collected together in parcels, to be delivered, in this case to Turin.
In 1838 there wasn't trains, so most probably the letter has been delivered by a coach. The coach has crossed the border, but there was not a specific office at the border, so the parcel with all the letters to France went directly to the Turin delivery office. In this office, the parcel with all the letters has been opened and the letters "worked", so marked (TS), resorted by their destination and delivered.
The second delivery (i guess still by coach) was directed to France, to the office of Pont-de-Beauvoisin. In this case, unlike before, at the border there was a specific office arranged for this purpose "by postal convention", so by a specific agreement among France-Sardinia. In this office, the second parcel has been opened and again the letters "worked", so marked (ITALIE P LE PONT-DE BEAUVOISIN), sorted and dispatched. To regulate the accounting between the two postal administrations (French-Italian), the letters were counted, the dues calculated and recorded into a register. We can think as if the letters coming from Sardinia directed to France was "sold" to the french postal administration.
So, when the postman finally delivered the letter and collected (hopefully) the related fee, the entire collected fees remained to the French post, which on the other side, paid the resulting from the accounting in the exchange offices to the italian posts.
I hope i could have been clear...
So, not all the time a letter crossed a border it was marked. A marking always refer to a "work" on the letter, either collecting, sorting, distributing, etc.
So why the LI? LT? LJ? Where have they been applied and for which reason?