In the XIX century Warsaw had, at different times, Prussian, Polish, Russian and again Polish local administration. There are numerous ways the surname could have been misspelled, the English spelling you have is unfortunately too far removed for a reasonable guess. Oh and Warsaw at the time had about 30% Polish population - so are you 100% sure it's a Polish surname? It could be 'Szemiński' (that's male form, female would be 'Szemińska') but that's quite a far fetched guess.