The letter is likely highly reliable, and possibly includes information extracted from a family bible given the birth/marriage/death dates cited.
Transcript:
Page 1
Evan R Jones of North Wales and Jane Thomas of Llandillo, South Wales were united in marriage June 17th 1858. Jane Thomas was a sister to the Thomas Bro of the firm T Thomas and Sons, Tanners, Bootmakers and Woolstaplers of Llandillo and Carmarthen, S. Wales.
The first child to bless this union was a daughter, Sara Jane. She was born in Mountainash, Glamorganshire, S. Wales, May 6, 1859.
In 1861 they came to America at the beginning of the Civil War. Jane was less than 2 years old when they arrived in America. She married very young to David Howells.
They had 2 children, girls, and at the birth of the 3rd child both mother and child passed away. The girls names were Olwen and Maggie Jane.
Page 2
1. Olwen Howells married Ceradoc Rees, they lived in Nanticoke, Pennsylvania.
Children
Jane - married Arthur Harris - 1 child - Rees Harris
Ceradoc - single, died at age early 20s
Ann - single
Ralph - single - Professor at Bucknell U.
Willard - died when a young child
2. Maggie Jane married Frank Shanley and they lived in Olyphant Pennsylvania.
Children
Nellie - single, born May 26 1896 died Mar 18 1967
Elizabeth - single, B Nov 20 1899
William - died in infancy
Francis - married Gertrude Kelly He was born Feb 10 1902, died Jan 2 1954
Margaret - single
Joseph (there were two Josephs) - died in infancy
Joseph - single - Born Oct 30 1907 Died Sep 4 1976
Mary - married George Walbush - Born July 22 1910
Olwen - married Edward Hayes - Born Oct 15 1912
Catherine - married Francis Brennan - B Nov 28 1916 D Jun 7 1952
Ann - stillborn
Page 3
1. Francis Shanley and Gertrude Kelly
Children
Jean Marie - marred Frank Van Nort
Ann - single
Frank - married Jane Weller
Margaret Mary - married Pete Boretsky
William - married Jacqueline Mackell
Joseph - married Paula Baumgartner
James - married Diane Grabin
2. Olwen Shanley - Edward Hayes
1 child Mary Hayes married James Harbottle
3. Catherine Shanley - Francis Brennan
1 child - James Brennan married Mildred Naglak
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