It was apparently an insurance scam! As he turned up in America in Barnum and Bailey's Circus and died in America. He didn't marry and there are no descendants. In his will he mentions his sister (who had emigrated from the IOM with her husband, Robert Gelling a miller, and lived in new York state). There is a very good article "The Mystery of Arthur Caley, the Manx Giant" by Ruth Serjeant which also states that the Giant's eldest brother john Thomas emigrated to the states and has descendants in Rochester, New York. The article was in a publication in the Museum Library - maybe the Antiquarian's journal. Maybe it is on Frances' site? My husband is descended from the Giant's sister Eleanor who married James Mylrea.