This is the tombstone of Joseph and Lucinda Merkle, located in row 1 of Zion Lutheran Cemetery, Chattanooga, Mercer County, Ohio. The marker is inscribed:
Several census enumerations indicate that Joseph was born in Germany but none of the documents I have looked at on-line indicate who his parents were. His Mercer County death record does not name his parents and neither his death nor his burial is recorded in Zion Chatt’s records.
I noticed that Merkle was occasionally spelled Merkley and Kantner was sometimes spelled Kentner in some records.
Joseph Merkle married Lucinda Kantner 29 January 1860 in Auglaize County, Ohio. His name was recorded as Merkley and hers as Kentner on their marriage record. 
Lucinda was very likely the daughter of Elias/Eli and Elizabeth (Oswalt/Oswald) Kantner. A Lucinda Kantner, the same birth year, was enumerated in the 1850 and 1860 censuses in the Eli Kantner household in Auglaize County, Ohio. Note that the 1850 and 1860 censuses do not show family relationships. However her father Eli applied for her marriage application since she was only 16 years old and needed permission to marry. 
The Eli Kantner household, Auglaize County, in 1850: Eli Kantner, 31, born in Pennsylvania; Elizabeth, 28, Ohio; Israel, 10; Catharine, 9; Lucinda, 7; Leah, 5; William, 4; and Mary, 1. All of their children were born in Ohio and Eli was a farmer. 
In 1860 the Eli Kantner family still lived in Pusheta Township, Auglaize County. In the household: Elias, 40, born in Ohio; Elizabeth, 38, Ohio; Israel, 19; Catherine, 18; Lucinda, 16; Lena, 15; William, 13; Mary, 11; Rebecca, 8; Emeline, 6; Sarah J, 4; Michael, 2; and Levi, 5 months. All the children were born in Ohio. Lucinda Kantner was 16 years old and her occupation was domestic. 
The problem here is that Lucinda married Joseph Merkle in January 1860 but she was enumerated with her family on 23 June 1860. Where was her husband Joseph Merkle when the census was taken?
The 1870 census was the first census in which I found Joseph Merkle. In 1870 the Joseph Merkle family lived in Wapakoneta, Auglaize County: Joseph, 34, born in Germany; Lucinda, 26, Ohio; Mary M, 9; Elizabeth, 4; Anna, 2; and John, 5 months. All the children were born in Ohio and Joseph was a blacksmith. 
The Joseph Merkle family moved to neighboring Mercer County by 1876, where their son Friedrich was baptized at Zion Chatt in September of that year. In 1880 they resided in Chattanooga where Joseph was a blacksmith in the village. Their household in 1880: Joseph, 44, Wuerttemberg; Lucinda, 37, Ohio, wife; Mary, 19; Elisabeth, 14; Anna, 12; John M, 10; Frederic, 8; Emma, 5; and William, 3. 
Joseph, Lucinda, and their family attended Zion Lutheran Church when they lived in Chattanooga. Lucinda was confirmed as an adult at Zion on 17 May 1885 and over the years several of their children and grandchildren were baptized, confirmed, and married there. Lucinda’s confirmation record gives her date of birth as 12 October 1842 but does not give the names of her parents.
Their Liberty Township household in 1900: Joseph Merkle, 64, Germany; Lucinda, 56, Ohio; William, 23; Edward, 17; and Leo, 11. This census indicates Joseph immigrated in 1852 and that Lucinda had given birth to 10 children but that only 8 were living in 1900. Lucinda and all the children were born in Ohio. Joseph’s occupation was day labor. 
Joseph Merkle died 11 April 1901 in Liberty Township, Mercer County, Ohio, at the age of 35. His occupation was a blacksmith and he was born in Germany. 
In 1910 Lucinda, age 66 and a widow, lived in Liberty Township with her son Leo, age 21. Leo worked as a clerk in a general store in Chatt. This census also indicates that Lucinda had given birth to 10 children and 8 were living at that time. It also indicates that her parents were born in Pennsylvania. 
According to Zion Chatt’s records Lucinda Merkle died of asthma and dropsy on 20 November 1919 in Mercer County, Ohio. She was buried on the 23rd with Rev. J.E. Albrecht in charge of the service. The church records indicate that Lucinda was survived by 2 sisters, 1 brother, 4 sons and daughters, 24 grandchildren, 9 great-grandchildren.
Joseph and Lucinda (Kantner) Merkle had the following nine children that I could identify, but the 1900 and 1910 censuses report that she had given birth to ten children.
Maria “Mary” (1861-1954), married Rev. A.J. Feeger
Elisabeth (1865-1924), married Jacob Joseph Heffner
Anna (1867-1935), married Friedrich Heffner
John Francis (1869/70-1895)
Emma (1874-1950), married Conrad Heffner
William (1877-1959), married Bertha Short
Joseph “Edward” (1882-1952), married Nellie Dull
Leo (1888-?), married Clara Baker
 “Ohio, County Marriages, 1789-2013,” database with images, FamilySearch(https://familysearch.org : accessed 26 Jun 2016), Joseph Merkley and Lucinda Kentner, 29 Jan 1860; from Auglaize County Marriages Vol. 2, p.241, from FHL microfilm 963056.
 1850 U.S. Census, Pusheta, Auglaize, Ohio, p.335A, dwelling & family 608, Eli Kentner; digital image by subscription, Ancestry.com (www.ancestry.com : accessed 26 Jun 2016); from NARA microfilm M432, roll 660.
 1860 U.S. Census, Pusheta, Auglaize, Ohio, p.426, dwelling 512, family 496, Elias Kantner; digital image by subscription, Ancestry.com (www.ancestry.com : accessed 26 Jun 2016); from FHL microfilm 803931, from NARA microfilm M653, roll 931.
 1870 U.S. Census, Wapakoneta, Auglaize County, Ohio, p. 36 (penned), dwelling 304, family 298, Joseph Merkley; digital image by subscription, Ancestry.com (http://www.ancestry.com : accessed 18 May 2014); from FHL film 552671, from NARA film M593, roll 1172.
 1880 U.S. Census, Liberty, Mercer County, Ohio, ED 188, p. 2 (penned), dwelling 13, family 14, Joseph Markrle; digital image by subscription, Ancestry.com (http://www.ancestry.com : accessed 18 May 2014); from FHL microfilm 1255048, from NARA microfilm T9, roll 1048.
 1900 U.S. Census, Liberty, Mercer, Ohio, ED 85, p.10A, dwelling 186, family 191, Joseph Merkle; digital image by subscription, Ancestry.com (www.ancestry.com : accessed 26 Jun 2016); from FHL microfilm 1241304, from NARA microfilm T623, roll 1304.
 “Ohio, County Death Records, 1840-2001,” database with images, FamilySearch (https://familysearch.org : accessed 25 Jun 2016) Joseph Merkle, 11 Apr 1901; from Mercer Deaths; from FHL microfilm 914954.
 1910 U.S. Census, Liberty, Mercer, Ohio, ED 119, p.16B, dwelling, family, Luinsindy Merkle; digital image by subscription, Ancestry.com (www.ancestry.com : accessed 26 Jun 2016); from FHL microfilm 1375227, from NARA microfilm T624, roll 1214.