nach niederlande - postmarke ?

Hello all!

I have noticed some similar markings on letters incoming to Amsterdam in the 1860's. Examples are shown below.

They are a series of numerals, some in black, some in blue. Is there a postal significance here? I also often see the numeral that looks like a '2' or '6' in red or blue on items arriving in Amsterdam. One item is from France, the other, Italy. I have others, but just found the file sizes to be too large, so will work with them later.

Suggestions as to where to look to figure this out would be appreciated.

My thanks,
Rob

Here are the fronts of the covers shown above.

One from France to Amsterdam and the other from Italy to Amsterdam.

French cover:
Double Weight Letter - 40 ctms per 10 gms : Apr 1, 1868 - Dec 31, 1875

Paris P De La Bourse Jun 3, 1868
Amsterdam Jun 4, 1868 (verso)

Italian Cover:
50 centesimi per 10 grams: Jan 25, 1868 -
Firenze Ufc Succursale N.4 Apr 28
(Branch Office Number 4)
Franco (paid)
P.D. (paid to destination)
Verona Apr 28 1868 No 3
train #3 to Milan
rail to Como
steamer on Lago di Como to Colico
coach to Splugen
Chur-St Gallen Z14 Apr 30 68
(Zug 14 - train #14)
K Wurtt Fahrnd Postamt
(Wurttemburg ambulant post office)
Amsterdam 2 Mei 68

Here is another one (note list of numerals at right on back portion of folded letter):
France to Amsterdam
Triple Weight Letter

Paris P De La Bourse Jun 22, 1870
1 in star
Amsterdam Jun 23, 1870 (verso)

And yet another. This one is for the prior 60 centime rate. I still need to write it up.

But, again, here are the numerals.

Rob

Dietmar,

How did I MISS that?!?

No, it is still interesting to me (and perhaps I'll say more on that later). But, that is so terribly obvious now that you say it.

And this is why it is wonderful to have access to this forum. I would have seen this eventually, but I clearly had a blind spot. Wow.

My thanks.
Rob