In the book's own words, not ours, with obvious scanning errors fixed. Families often supplied these stories to the publisher, so check key dates.
Born 1825
From History of Johnson County, Iowa, containing a history of the county, and its townships, cities and villages from 1836 to 1882. Together with biographical sketches .. (1883)
Z. SMITH, farmer and stock-raiser, post-office. Oasis; born in England in 1825; came to Philadelphia in 1848, and while there he married, in 1850, Miss Anna Harrison. He went from there to Salem, Ohio, and in November, 1854, he came to Iowa and settled in Graham township, where he now lives. Mr. Smith has eight children living, his oldest married and living in Cedar county, and a daughter married and living in Cass county, Iowa.
As printed in History of Johnson County, Iowa, containing a history of the county, and its townships, cities and villages from 1836 to 1882. Together with biographical sketches .. (1883). See the original pages. Wording is the original; obvious scanning errors have been corrected, and a few may remain.
The printed record stops around 1883. We trace your line from there down to you, with every source cited.