The 8,8cm S.K. L/30 is a German Naval gun produced by Fried. Krupp in 1891.  These weapons were obsolete by the WW1 Era but were still in limited service with German Auxiliary Cruisers and Coastal Fortifications.  It seems very likely this piece came from the Auxiliary Raider Crown Prince William.  In this type of service, the gunner's seat and shield were often removed, as is so with our 8,8cm.

Two guns carried onboard the SMS Königsberg were of this same type.  They were also to go to a German Merchant Ship but the SMS Königsberg was disabled in German East Africa's Rufiji River Delta.  These guns were then recovered along with the 10,5cm guns from the ship itself for field use by the Colonial German Troops.  One of these German East African field modified 8,8cm S.K. L/30 still exist.  See this link for the article by MC Heunis and Vincent Wratten :
http://www.sacktrick.com/igu/germancolonialuniforms/militaria/koenigsberggun.htm 

Above: Another photograph of Leon and Ralph Lovett firing the 8,8cm. S.K. L/30 in reproduction Kaiserliche Marine Uniforms

Above: Original photograph of an 8,8cm. S.K. L/30 with the shield and gunner's seat pictured with its crew in winter uniforms

We are looking for the direct fire sight for the 8,8cm. S.K. L/30. If you have one for sale or trade please contact lovett155@hotmail.com