Trying to decipher marks on thundermug

[cannonmn]

Item:  Spanish bronze signal mortar, aka "thundermug"
 
Provenance:  Surrendered to US Army, Philippines, 1902, thereafter in Elihu Root and Grant Family collections until 1986.
 
Dimensions:  Height 11 in.  Base diameter:  8 in.  Muzzle diameter:  4 in.  Bore diameter:  2 in.  Wt:  About 50 lbs.
 
Marks (four sets): 
Año_de_1869
N_x
Unknown monogram of .M. and reversed S
P_
 
Photos: 
Password is "attack"
 
http://s17.photobucket.com/albums/b62/cannonmn/miscforumsetc/Forums60/Lg%20Thundermug/?albumview=slideshow#/grid
 
I'm primarily interested in the meaning of the ".M." with reversed S overlayed on right leg of the M.  I've never seen that symbol before.
 
I don't know what the P means either but I'm not sure it is anything important.
 
The N_x may mean it is thundermug number ten.
 
The date of manufacture is obvious.
 
Thanks for any help or suggestions.

[Zulu]

You come up with the neatest stuff!  Is this in your collection?
Zulu

[cannonmn]

The thundermug is one of four items I got in a trade in 1986, which had all been in the Elihu Root collection.  There was the small Spanish cannon mentioned in another topic, this thundermug, a suit of Moro armor made of brass chain mail and tortoise shell with a brass "Conquistador" type helmet, and a large Italian painting of a sea monster attacking a galleon.  The painting had hung in Root's office when he was NYC police commissioner and I have no idea where he got it.
 
We fired the thundermug and put the video on you-tube.  It gets a lot of criticism because of the way the camera man bosses the gunner around.  It was all in fun but much of the audience doesn't realize that.  We used 2FA blasting powder which wasn't a good choice, it doesn't burn fast enough for a thundermug.  You can hear the large unburned grains hitting the ground in the video.

[cannonmn]

I think I have the "P_" figured out.  All Spanish bronze cannon are marked with the weight even if that's the only mark on them, which it is for some of the smaller pieces.  The weight mark is often preceded by a P or a Po, standing in either case for "Peso" the Spanish word for weight.  When this piece was engraved, the scale was broken, or it wasn't anywhere near a scale, and filling in the actual weight was postponed.  For a long time, I might add.
 
Usually Spanish bronze artillery pieces, except the very smallest, have some mark of the King or Queen, either the Spanish coat of arms or with smaller pieces, merely a stylized "R" for "Real" meaning royal.  In 1869 there was no Spanish monarch except Isabella II who had gone to France in exile, so I have no idea what they would have substituted if anything.

[cannonmn]

Made some progress on this but still need help.  I finally realized that the weight mark wasn't incomplete at all.  I saw it as a P_.  What it is is a monogram of P and L.  It weighs about 50 English pounds and Spanish pounds are pretty close, so the L is the roman numeral for 50.   The precise meaning of this mark, I think, is "Weight of this piece is 50 pounds."  The engraver just had a quick shorthand way of doing it.
 
I still need the meaning of this mark; I'm convinced someone here knows what it means.  Some of our members from the Land of the Limes are very good at this, wonder where they are?
 

 
 
 
 

[cannonmn]

Maybe a bit more info would help you.
 
1.  This "MS" mark is probably one of two pieces of information normally found on Spanish bronze artillery pieces which remain un-accounted-for on this one.  Those include the mark of ownership, which during the 19th C. normally reflected the Spanish Monarch's name, such as "Isabella Rex II" or "Ferdinand Rex VII" or "Carlos Rex IV" (Rex of course means King or Queen.)  This would be represented by a 'cypher" or monogram of one roman numeral or sometimes arabic numeral if it would reqire more than four characters, so what I've seen for Ferdinand was "C7."  But I don't see how this would reflect any one of the many people who came and went as head-of-state in Spain in the late 1860's.
 
2.  The other piece of un-accounted-for information is the place of manufacture.  If cast in Spain it would always be at one of the two Royal Cannon Foundries, Seville or Barcelona, and that full name would be engraved on the basering of the cannon.  If made in the Royal Foundry (Arsenal?) of Manila, normally "Fundicion Manila" would be spelled out in the same place.  There was a good chance this was cast at the Manila arsenal, but I've never seen any kind of abbreviation for that establishment.

[GGaskill]

Perhaps the "S" is supposed to be a stylized pennant flying from the top of the M.

[cannonmn]

  Perhaps the "S" is supposed to be a stylized pennant flying from the top of the M.

There's something I hadn't considered.  Thanks.