1.  Anon.  1966.  Marriage Index:  Ohio, 1789-1850.  Liahona Research, Orem, UT (Broderbund CD-400):

Eckert, Jacob	Shellenberger, Kitty	9 Nov 1807	Fairfield Co.
Johnston, John B	Knode, Rebecca	27 Apr 1809	Fairfield Co.
Eckert, Jacob L	Johnston, Rebecca	12 Feb 1817	Fairfield Co.
Ream, Jacob	Eckart, Elizabeth	8 Apr 1819	Fairfield Co.
Eckart, Lemot	Vantrace, Nancy	25 Jan 1829	Fairfield Co.

2.  1810 Census Index/Images (online at Ancestry.com):  the Ohio census was lost (except for Washington County).  Tax lists are substituted on the CD where available, and while there are some Fairfield County records, there's no Jacob ECKERT (or variation), but the number of records is obviously well below what there should have been for the county (i.e., the tax lists are not complete).

3.  1850 Census Every-Name-Index/Images (online at Ancestry.com, Image #34 of 64):  Bern [Berne] Twp., Fairfield Co., OH, Roll M432_677, p. 447B, 219/237, enumerated 15 Sep 1850, official enumeration date 1 Jun 1850 (extracted by Diana Gale Matthiesen):

Eckhart Henry	34	M		Farmer	2400	Ohio
Eckerts Jacob	4	M				Ohio
Eckert An?? Maria	31	F				Ohio
Eckert George	3	M				Ohio
Eckert Catharine	1	F				Ohio
Eckert Mary E	2/12	F				Ohio
Muck John	15	M		Laborer		Ohio
Eckert Catharine	37	M				Ohio
Parks Courtny	22	M		Laborer		Va
Quinn James	33	M		Laborer		Ireland

7.  1860 Census Every-Name-Index/Images (online at Ancestry.com, Image #31 of 57):  Lancaster P.O., Bern [Berne] Twp., Fairfield Co., OH, Roll M653_961, p. 353B/704, PN 124, 893/908, enumerated 2 Aug 1860, official enumeration date 1 Jun 1860 (extracted by Diana Gale Matthiesen):

Catharine Eckert	46	F			1260	185	Ohio
T.H.B. McCausland	20	M		Farmer	550		do
James H    "	11	M					do
John E     "	11	M					do

The three males are the orphaned children of Catharine's late sister, Sarah (ECKART) McCAUSLAND.

8.  1870 Census Every-Name-Index/Images (online at Ancestry.com, Image #21 of 22):  Thompson Twp., Delaware Co., OH, Roll M59_1196, p. 505A, PN 21, 171/171, enumerated 9 Jul 1870, official enumeration date 1 Jun 1870 (extracted by Diana Gale Matthiesen):

Ecket Cathern

55

F

W

House Keeper

600

Ohio

Listed next to her McCAUSLAND nephews.

9.  1880 Census Every-Name-Index/Images (online at Ancestry.com, Image #8 of 18):  Thompson Twp., Delaware Co., OH, Roll T9-1012, p. 298D, PN 8, SD 5, ED 103, enumerated 7 Jun 1880, official enumeration date 1 Jun 1880 (extracted by Diana Gale Matthiesen):

1880:  for an explanation of the column headings, please see What the Numbers in the Federal Census Mean (missing columns contained no data).

1

2

3

4

5

6

8

9

11

13

24

25

26

75

78

McCausland James

W

M

31

/

Farmer

OH

PA

OH

__________ Jacob

W

M

31

/

Farmer

OH

PA

OH

Catherine

W

F

65

Aunt

/

Keeping House

OH

PA

PA

Abbott Martha

W

F

20

Servant

/

Servant

OH

OH

OH

The record is ambiguous with regard to Catherine's surname.  There's no horizontal line indicating "ditto" for Jacob's surname being the same as James's, as there is for Jacob, nor is Catherine's given name lined up with James's and Jacob's.  Surely this is Catherine ECKERT.

10.  1890 Census:  the 1890 Census Population Schedules were destroyed.

11.  1900 Census Every-Name-Index/Images (online at Ancestry.com):  Catherine not found.

12.  Fairfield County Cemeteries:  Bern Township:  Crawfus-Emery Cemetery (online at the "John Hancock Eckert" web site of Mary and Don Saban):

Row 15 Eckert, Jacob L. died October 12, 1818 29y Born Lancaster County, PA Katherine w/o Jacob L Sept 7, 1816 28y 3m

13.  Jean Collier, compiler.  1996.  Fairfield County Wills and Estate Abstracts, Cases 1-500.  Ohio Genealogical Society, Fairfield County Chapter (online at the "John Hancock Eckert" web site of Mary and Don Saban):

PG 29 Case #266 estate of Jacob L ECKERT of Berne Twp. Filed in 1817.  Jacob L. ECKERT owned land in Berne Twp, Fairfield Co (Sec 21) and in Good Hope Twp of Hocking Co (Sec.s 14 & 23).  By 1837, Rebecca, widow of Jacob L ECKERT, was married to Jacob HINE.  The children were:  Henry L ECKERT; minors, Catherine, Jacob and Sarah ECKERT, whose guardian was John GRAYBILL; minor George ECKERT, whose guardian was George CANODE; minor, Lemunday ECKERT, who guardian was Isaac COONS; minors, Lewis and Sally ECKERT, whose guardian was Samuel SHELLENBARGER.  George ECKERT, Sr. of Lancaster Co, PA, had willed Jacob ECKERT the land in Green Hope Twp of Hocking Co.

How could Jacob's will have been filed in 1817 if he died in 1818?  Has his tombstone been mis-read?  Rebecca married Jacob HINE more like 1857.  Rebecca was still surnamed REAM in the 1850 census, and Jacob HINE was still married to Margaret in 1850.  It's possible Rebecca Elizabeth married a different Jacob HINE in the 1830s, then was either widowed or divorced from him by 1850 and went back to using her prior husband's surname, though that explanation is harder to swallow than that someone simply misread a 5 for a 3 — or made a typo.  It's also hard to figure why Henry was not a minor with a guardian; he was a mere babe in 1817.  Jacob died just under 11 years after he married, so none of his children could have been of age when he died.  This will should be re-examined.  I suspect Henry will turn out to be one of the minors whose guardian was Jacob GRAYBILL.

14.  Our Shallenberger Family in America (online at Virginia Carpenter Jansen's web site).

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