Thank you Wanda! Unfortunately it was Jalyn, who had an August Ernst in her tree. MY Ernsts came from Hanover and since last weekend I know that three (!) Brothers of my ggrandfather came to New York (I ever thougt there were two).
Johann Friedrich Reinhard Ernst * 1863, lived 243 East III Street New York (in 1890), Johann Reinhard Ernst * 1868 with the same adress and Johann Ehler Ernst * 1869, lived 833 Sixth Avenue New York. Johan Friedrich probably married Amada Schroder (or Amanda?) and they had a son Johann Friedrich Reinhard Ernst * 1888, he was already born in NY.
Unfortunately I can´t find anything else at the moment (neither in rootsweb nor at other adresses I know, so any help is appreciated! Regards and thank you again! Andrea