"Tad Lincoln's Cannon"-a strange beastie

[cannonmn]

I've been puzzling over this approx. 11-inch long top-quality antique model for about a year.  It is at the Lincoln Museum in IL.  It is supposed to be Tad Lincoln's cannon, given to him by Captain John A. Dahlgren ca. 1862, but I was never able to find out the exact provenance.  Somewhere I have more info on measurements and marks but can't lay hands on 'em now.

The word visible on top is obviously "Howitzer" and the model is obviously some never-manufactured version of the Dahlgren Boat Howitzer.  Note that the elevating screw is inverted.

Anyway, go figure.




http://i17.photobucket.com/albums/b62/cannonmn/miscforumsetc/forums24/IMG_1670.jpg
http://i17.photobucket.com/albums/b62/cannonmn/miscforumsetc/forums24/IMG_1672E.jpg

[dominick]

I think who ever had it apart screwed the adjuster in upside down.  Notice the retaining slot in the very top part [the actual bottom] of the screw near the knurled disk.  It appears to be the same type adjuster as used on a boat howitzer.

[gary michie]

And it has a ball on the tip.
gary

[cannonmn]

Note that the elevating screw is inverted.

OK now what is it?  Only one smoothbore Dahlgren boat howitzer on record had trunnions, and that was the prototype that only weighed about 220 lbs., engraved "The first gun cast in this ...." which was cast in 1849.  I guess I should re-locate the dimensions of the model and see if it scales to a "known" boat howitzer model.  I thought I tried that a while back, but I know I didn't try all the possibilities.

[cannonmn]

Model is bronze, smoothbore, no underloop, only trunnions.
 
Marks:  Top of barrel:
 
An anchor
12 Pdr (dr in superscript with dots underneath)
BOAT HOWITZER
1862
JAD
 
 
This model lacks any manufacturer, registry, weight, or preponderance marks on top of breech.  Perhaps if this was a proposed or experimental design, it makes sense that no such marks were applied.
 
Measurements: 
 
Barrel 12 in. long
Bore 3/4 in.
Wide end 1 7/8 in. dia.
Narrow end 1 7/16 in. dia.
 
 
My attempt to interpret the measurements:  The simplest measurement to use on scale models is the bore diameter, since bores were in standardized calibers.  Thus the ratio of the model's "3/4 inch" bore to the regulation 12-pounder bore diameter is 0.75/4.62 or about 1:6 ratio.  So I would expect this to be a one-sixth scale model.  Extrapolating the model's barrel length, the "regulation" 12-pounder "heavy" boat howitzer's barrel measured 63.5 inches overall length.  Taking the model's length of 12 inches times the 6 scale factor gives 72 inches, significantly longer than the regulation heavy boat howitzer of that caliber.
 
This piece fascinates me because I'm fairly certain the model was made at the Washington Navy Yard, and if so, it represents a heretofore unknown design variant (even though never manufactured in full size) of the famous Dahlgren Boat Howitzer.
 

[cannonmn]

I may have found out what this "unknown" model of Dahlgren boat howitzer really is.  I was looking through my microfilm of old records of what miscellaneous ordnance was at the Washington Navy Yard ca. 1870's.  The photo shows a page including this description of a cannon:

Experimental 12 pdr.  1398 lbs.  No. 1 Cast May 1852 WNY ......

Since it was cast at the Washington Navy Yard, it was bronze, that's the only material the WNY used for cannon casting in their foundry.  1398 lbs. is somewhat heavier than a rifled Dahlgren 20 pounder, which had a profile very much like that of the model.

I'm fairly well satisfied that the 12 pdr. mentioned in the old records is what the model represents.

[cannonmn]

There's another issue I have concerning whether this model cannon really belonged to Tad Lincoln.  The Lincoln museum bought it at auction in the 1950's, with no documentation as to its provenance, other than perhaps an auction catalog description. 

Tad Lincoln is well-known to have what is usually described in various sources as a "toy cannon."  The toy cannon was capable of projecting some type of small cannonball (marbles?) a short distance, perhaps a few yards.  Many sources mention an incident where Abe Lincoln was meeting with his cabinet behind closed doors, and Tad "fired" his toy cannon at the door a number of times until President Lincoln opened it.

The Navy Yard model cannon isn't capable of firing using gunpowder in my judgment, the scale model vent, if drilled through at all, would be 1/6 x .02 inches, or 0.03 inches.

Then again, there's nothing that would rule out Tad Lincoln having owned the Navy Yard model since there is documentation that Capt. Dahlgren, USN, presented a small cannon to Tad Lincoln.  I haven't run across any description of that cannon however.

If anyone can shed any light on this historical dilemma, please do so.

I've started another discussion on the Ebay "toys and hobbies" forum to see if anyone knows about the "toy cannon." 

http://forums.ebay.com/db1/thread.jspa?threadID=510069769