Have you just tried googling his name? There are texts readable on googlebooks and several of his marriages are found in newspaper archives, he seems to have been quite the character.
A Century and a Half of Pittsburg and Her People, Volume 3
By John Woolf Jordan
History of Pittsburgh and Environs, from Prehistoric Days to the Beginning ...
By George Thornton Fleming, American Historical Society
both include the following info.
On the paternal side his ancestry traces from the great grandfather Henry Mercer I, who came from Holland to this country in 1760 and was a soldier in the Revolutionary struggle was with General Washington the night of December 25, 1776 when he with twenty four hundred men crossed the Delaware river at Trenton the day before the battle at that city where the Continental forces captured fifteen hundred British soldiers and one thousand Hessians.
Henry Mercer had the distinction of being in the same boat with Washington on that eventful night . He married Hannah who came from Holland, they were married in this country and had among other children one son named James Mercer II the subject's grandfather. After the close of the Revolutionary war the American ancestor Henry Mercer moved from near Philadelphia, where he originally settled to
York, York county Pennsylvania ,where he had been given a grant of land on which the city of York now stands.
James Mercer married and had a son James 2, who became the subject's father.
Dr Askelon Mercer, the father, was born in Beaver county Pennsylvania in 1848. He was a practicing physician, in church relations, a Baptist and in politics, a Republican. He married Eugenie C Sheets daughter of Dr A and Mary A Dustin Sheets. The subject's mother is a direct descendant of the Dustin family of Haverhill, Massachusetts to which belonged the famous heroine Hannah Dustin who was born in 1660 and in 1697, when Haverhill was attacked by the Indians, was made a captive with forty others who were made prisoners or killed at that place. Herself, her servant and a boy killed ten or twelve Indians when they slept and thus made their escape. Eugenia Sheets Mercer was born in 1850 and became one of the first women physicians to practice medicine in the state of Pennsylvania. In her religious faith she is the same as her husband. Dr Askelon Mercer and wife were the parents of three children including the subject Harry Frederick.
Eugenie C . Sheets Mercer was born in 1850 and became one of the first women physicians to practice medicine in the State of Pennsylvania. In her religious faith she is the same as her husband, a Baptist. Dr Askelon Mercer and wife were the parents of three children including the subject Harry Frederick. Harry Frederick Mercer obtained a good primary education at Hiram College Hiram Ohio and then was admitted to the law department of the University of Michigan at Ann Arbor from which he graduated in 1903 and at once commenced the practice of his profession at Pittsburgh Pa where he is now counted among the successful attorneys of the city. Politically Mr, Mercer is a supporter of the Republican party. He is identified with the Presbyterian church and is a member of the Free and Accepted Masons. Mr. Mercer married Oct 24, 1906 at Pittsburgh, Pa, Estella M. Brown, daughter of Joseph S and Matilda Brown of Pittsburgh. Children; Dorothy E, H Frederick Jr., Marjorie, James Dustin deceased and Eugenia C.
Dr Askelon Mercer aged 75 of Beaver Falls and Sarah L Calgrove aged 65 of county W Va married themselves at the home of the bridegroom last light. When the license was issued to the old couple he declared that he had been married five times and in each instance had done the marrying himself. He said that his last marriage occurred May 3, 1904 and he secured his divorce May 4. 1903. He said that his sensible and inexpensive form of marriage was always attended by two witnesses and that he always went into the court to secure his divorce in a legal and rational way. Poor Girl. May I tell you the old old story, asked, She looked down blushed and nodded her assent. So he told for the time how once won the for Brooklyn Life. Prepare. Never write on a subject first having read yourself full of it and never read on a subject till you have thought yourself it.
Dr Askelon Mercer, 75, and Beth Calgrove ,65, performed their own marriage ceremony at Beaver, Pa yesterday. In the presence of witnesses. This is the groom's fourth matrimonial venture and he declares that all former ceremonies were performed in the same manner tli at the deposed preacher Knode Cooke has at last ded his affinity and soul mate E Whaley his elopement with whom years ago was by the procuring at a divorce by his former wife the world and his wife may well allow the couple to drift into the oblivion that is sure to come .