This is a small bronze cannon with following characteristics:
Present weight: 138 English pounds (62.7 Kg)
Bore 2.27 in. (57.7mm)
Trunnion diameter 2.14 in. (54.4mm)
Trunnion length 2.0 in. (50.8mm)
Nominal length 36 in. (91.4cm)
Total present length 38 in. (97cm)
Muzzle Diameter 4.27 in. (108.5mm)
Basering Diameter 5.7 in.(144.8mm)
Present vent Diameter 0.33 in. (8.38mm)
Markings: Right Trunnion; "No. 89"
Left trunnion: "142"
Under basering "7"
Theory: I believe this is an example of a previously unidentified French swivel cannon model, dating from the 18th C.
Rationale: The trunnion end markings are the same type found on either trunnion of the well-known French Model 1786 "Pierrier" swivel cannon. The registry number "No. 89" indicates that at least 88 other swivel cannons of the same type were cast under a government order. We know it is a government piece since no private entity would order 89 or more very expensive bronze swivel cannons.
This cannon has been converted for line-throwing as were many pieces of the two other "known" models of French swivel cannons, the M1786 and the smaller Espingole. I've personally inspected examples of either which had been converted to line-throwing duty by the French government, after being phased out of service in the French Navy. The converted M1786 pierrier I examined had a similar conversion in the vent area, in that the original vent had been plugged, and a new, forward-leaning vent had been drilled and bouched forward of the original vent.
In the specimen under discussion, one additional measure has been taken to convert it for line-throwing, in that the original integral "monkey tail" or tiller, has been neatly removed. This would account for the difference in actual weight and marked weight of the piece. Converting the 142 old French "livre" to English pounds makes the original (marked) weight about 153 lbs. Since present weight is only 138 lbs., the missing tiller must have weighed about 15 lbs.
I consider William Gilkerson's "Boarders Away II: Firearms in the Age of Fighting Sail" to be the "bible" of swivel guns. It is certainly the most extensive and most accurate work available on the topic. This model is not mentioned in the book, probably because this example had not been identified at the time the book was written.
On pp. 66-67 Gilkerson writes: "...another French swivel cannon originally categorized in contemporary French ordnance lists as "canon 'a queue" (cannon with tail), a term which appears in documents as early as 1768 when over 300 were inventoried in the three main French naval depots." It is possible that this term, used at that early date, in fact referred to the model of swivel cannon I have described, and not to the much lighter weapon that was later called the "Espingole," as described and pictured by Gilkerson.
As always, any and all comments and criticisms are welcome.
Additional photos of this swivel cannon:
Reference material on French swivel cannons converted to line throwing guns:
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