1.  The city of Minden is about 30 miles west of Hannover, near Bielefeld, in the state of Nordrhein-Westfalen, Deutschland [North Rhine-Westphalia, Germany].  Hamm and Dortmund are cities near Minden.  Düsseldorf (on the Rhine River) is the captial of Nordrhein-Westfalen.

2.  Kendall Co. was formed in 1862 from Kerr and Blanco Cos.; Blanco Co. was formed in 1858 from Gillespie, Comal, Burnet,and Hays Co.

1.  LDS.  Family Search: Internet Genealogy Service:  IGI - International Genealogical Index (online at FamilySearch.org).

Ernst Christian KAPP Spouse: Ida Sophie Conradine CAPPEL Marriage: 21 Dec 1833, Evangelisch, Hamm Dortmund, Westfalen, Preussen Source: Kirchenbuch, 1684-1966, Evangelische Kirche Hamm (StKr. Hamm)

Ernst KAPP Death: 30 Jan 1896 Father: Johann C.W. KAPP; Mother: Dorothea FRIEDLEIN Marriage: About 1834, Of Minden, Westphalia, Dusselforf, Rheinland, Preussen Spouse: Ida KAPPEL Birth: 25 Apr 1808 Father: Franz KAPPEL; Mother: Johanna HEINTZMANN Source: patron submission

2.  Chester William Geue & Ethel Hander Geue.  1966. A New Land Beckoned: German Immigration to Texas, 1844-1857.  [self-published?] (republ. 1972, Texian Press, Waco, TX; 1982 by Genealogical Publ. Co., Baltimore, MD; Broderbund CD-267):

p. 076	German Immigration to Texas, 1844-1847...
p. 107	Kapp, Dr. Ernst--38, arr. 1846; w--Ida nee Kappell; ch--Antoine, Alfred, Julia, Hedwig, Wolfgang; Comal Co. 1850; Kendall Co. 1860

3.  Ethel Hander Geue. 1970.  New Homes in a New Land:  German Immigration to Texas, 1847-1861. [self-published?] (reprinted 1982 by Genealogical Publ. Co., Baltimore, MD; Broderbund CD-267):

p. 48	German Immigration to Texas, 1847-1861...
p. 89	Kapp, Ernst, 41--Minden; Ida 41, Antonie 14, Alfred 12, Eulie 9, Hedwig 6, Wolfgang 3; Franziska, 1849; Sisterdale, Kendall Co. Kapp, Otto, 17--Hannover; Franziska, 1849

One would assume Otto KAPP was Ernst's son, except for his place of origin. 

4.  Index to Naturalization Records of Gillespie County, Texas (online at the Gillespie County TXGenWeb site):

Name	Record References	Country of Birth	Age	Date of Proceedings
Kapp, Ernst	Dist Ct Min Vol A p 174b Comal Co Nat File Box No A On 304 Comal Co Dist Ct Min Vol 1 p 175 Gillespie Co	Germany	42	May 7, 1850 DI May 7, 1850 DI Apr 12, 1855 GC
DI = Declaration of Intention; GC = Grant of Citizenship

5.  1850 Census Index/Images (online at Ancestry.com; Image #1 of 1):  "the Mountains," Comal Co., TX, Roll 910, p. 64B, 274/274, enumerated 11 Sep 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

Ernst Kapp	42	M		Farmer		Germany
Ether   "	42	F				"
Antone/Antoni "	15	F				"
Alfred  "	13	M				"
Julia   "	10	F				"
Hedweg  "	6	M				"
Wolfgag "	4	M				"
Canrad Bruns	17	M		Labourer		"
Anton Luehr?	15	M		"		"

The wife is not Ida.  It is definitely "Ether."  Does Ernst have a new wife?

6a.  1860 Census Index (online at GenealogyLibrary.com):  not found.

6b.  1860 Census Index/Images (online at Genealogy.com):  not found.

6c.  1860 Census Images (online at Ancestry.com):  not found, and I did page-by-page checks of Comal Co. and Gillespie Co. (Sisterdale should have been enumerated with the "Corporation of New Braunfels" in Comal Co., TX).

7a.  Glen E. Lich.  n.d. "Sisterdale, Texas." The Handbook of Texas Online (online at the Texas State Historical Association web site):  Ernst KAPP is mentioned in a capsule history of Sisterdale, Texas.

7b.  Terry G. Jordan. n.d. "KAPP, ERNST (1808-1896)." The Handbook of Texas Online (online at the Texas State Historical Association web site):  Capsule biography of Ernst KAPP, who was born 15 Oct 1808 in Ludwigstadt, Oberfranken, Bavaria.  He arrived in Galveston in 1849.  He and his wife, Ida KAPELL, and five children settled in Sisterdale, Kendall County.  Politically active.  At Sisterdale, ran a spa called "Badenthal" where he offered "Dr. Ernest Kapp's Water-Cure."  His log home survives, and Badenthal has been restored.  In 1865, KAPP returned to Germany for a visit, but illness prevented his return to America.  He died 30 Jan 1896 in Düsseldorf on the Rhine.  See bibliography.

8.  WorldConnect / Ancestry World Trees (online at RootsWeb.com/Ancestry.com).

9.  Adrian Ettlinger.   AniMap Plus: County Boundary Historical Atlas: with "SiteFinder," U.S. Place Name Database and U.S. Cemetery Database (on CD).  Gold Bug Software, Alamo, CA.  Using SiteFinder, it shows Sisterdale is in Comal County until 1858, then in Blanco County, then in Kendall County in 1862.