"190 A brass gun, with date, according to the catalog, "1798." On the chase the Turkish emblem, a star and crescent. On the 2nd reinforce a coat of arms nearly obliterated, beneath which is a Turkish inscription. The vent is in rear of the base ring. Length, 6 ft. 8 in.; calibre, 5.54 in."
You might try contacting
The Military Museum (Askeri Müzesi)
ValikonagI Caddesi
Harbiye Istanbul
Turkey
see
http://www.pbase.com/dosseman/miltary_maritime_museum
http://www.warmuseums.nl/gal/123gal.htm
http://wowturkey.com/forum/viewtopic.php?t=9555
http://www.tsk.mil.tr/askerimuze/askeri_muze.htm