HAMMOND, Ind. — In 1898, three nuns took a train to this city along the south shore of Lake Michigan to start a hospital. They converted an old farmhouse into a seven-bed medical center. They treated their first patient for a broken leg amid carpenters hammering nails. Surgeons laid their patients on a kitchen table for operations. The hospital — then named after St. Margaret, known for her service to the poor — eventually became one of the largest in the area. Hundreds of thousands of Indiana and Illinois residents took their first, or last, breaths there. A hundred twenty-four years later, t…