Isaac is 52 in 1851, a farmer of 28 acres born Turton.  He is a year younger than Jane his wife.  Did this Isaac emigrate to the USA, born 27-Oct-1798 and die aged 99?  An obituary for such an Isaac exists but seems to conflict with all the US census records.

Name:    Isaac Mather
Event Type:    Baptism
Baptism Date:    8 Jun 1800
Baptism Place:    Bolton-le-Moors, St Peter, Lancashire, England
Parish as it Appears:    Bradshaw Chapel
Mother:    Mary Mather
Reference Number:    L243/1/2/2
Item Number:    2
Archive Roll:    855
Text reads: "Isaac s. of Mary Mather of L.B." (no father given)

There's another Isaac Mather from Bolton recorded as born 27 Oct 1799, died 1898 (agd 99) who is said to have married three times, the last marriage being Sarah Langford, before they emigrated to the USA.  This Isaac was already in the US by 1850, and was actually born 1812, which explains why he was so fit at 99.  It is likely that this is the Isaac that was born 27 Oct 1799 (baptised 1800).  Also Isaac Mathers never married Sarah Langford. Sarah Langford married Morgan Pender and Isaac Mathers marries Esther Kershaw, both Q3/1838 at Manchester Collegiate Church which some Ancestry members have confused.

Died after 1861, but cant find a death record.  Perhaps he emigrated to USA with family (as did another Isaac Mather).  This death registered at Bury still seems likely for someone living in Edgworth:

Name    Isaac Mather
Estimated Birth Year    abt 1795
Registration Year    1867
Registration Quarter    Jul-Aug-Sep
Age at Death    72
Registration district    Bury
Volume    8c
Page    309

Lancashire Death indexes for the years: 1867
MATHER    Isaac    72    Radcliffe    Bury    RAD/11/18

Dont confuse with the death record index for Isaac Mather, husband of Elizabeth Marsden:
Lancashire Death indexes for the years: 1893
MATHER Isaac 79 Edgworth Bolton EDG/5/364

Can find no christenings for Sarah Jackson in Turton or Edgworth, and this is the only one for Bolton.  However, I would expect Sarah to have a son Robert (named after her father) and I havent found one.

SARAH JACKSON
Event(s):
Birth: 
Christening:  24 JUL 1796   Saint Peter, Bolton Le Moors, Lancashire, England
Parents:
  Father:  ROBT. JACKSON
  Mother:  SARAH

Cant find a death in Bolton, but the burial in Heaton confirms her age perfectly.
 

Name:    Ann Mather
Baptism Date:    1 Jan 1817
Parish:    Bolton-le-Moors, Lancashire, England
Father:    Isaac Mather
Mother:    Sarah Mather
Register Type:    Bishop's Transcripts
Reference Number:    Drm/2/21a

Ann daughter of Isaac & Sarah Mather, Edgworth, Weaver.

Name:    Anne Nelson
Estimated birth year:    abt 1817
Registration Year:    1894
Registration Quarter:    Jul-Aug-Sep
Age at Death:    77
Registration district:    Bolton, Lancashire
Volume:    8c
Page:    197

Lancashire Death indexes for the years: 1894
NELSON    Annie    77    Edgworth        EDG/5/418

Name:    Peggy Mather
Gender:    Female
Baptism Date:    4 Sep 1819
Baptism Place:    Turton, Lancashire, England
Mother:    Sarah Mather
FHL Film Number:    1545461

Sep 4th - Peggy Daughter of Sarah Mather, Edgworth, Weaver.

Aged 19 in 1841 (b.1822)
Aged 27 in 1851 (b.1824)

Name:    Joseph Mather
Baptism Date:    27 Jun 1822
Parish:    Turton, Lancashire, England
Father:    Isaac Mather
Mother:    Sarah Mather
Register Type:    Bishop's Transcripts
Reference Number:    Drm/2/39a

Abode: Edgworth, Weaver

Deaths Mar 1897   (>99%)
Mather     Joseph     75     Bury     8c    341

Aged 36 in 1861

Name:    Alice Mather
Baptism Date:    1 Jul 1824
Parish:    Turton, Lancashire, England
Father:    Isaac Mather
Mother:    Sarah Mather
Register Type:    Bishop's Transcripts
Reference Number:    Drm/2/39a
Abode: Edgworth
Fathers Occupation: Weaver

Name:    Alice Crawshaw
Estimated Birth Year:    abt 1825
Registration Year:    1870
Registration Quarter:    Apr-May-Jun
Age at Death:    45
Registration district:    Bury
Inferred County:    Lancashire
Volume:    8c
Page:    247

Aged 14 in 1841 (so not twins)
Aged 25 in 1851

Recorded as same age as brother Jacob in 1851 (i.e. a twin), but not a twin from the 1841 census.  However, baptisms together suggest they were close.

Name:    Peter Mather
Baptism Date:    3 Dec 1826
Parish:    Turton, Lancashire, England
Father:    Isaac Mather
Mother:    Sarah Mather
Register Type:    Bishop's Transcripts
Reference Number:    Drm/2/39a

Name:    Peter Mather
Estimated birth year:    abt 1826
Registration Year:    1874
Registration Quarter:    Jul-Aug-Sep
Age at Death:    48
Registration district:    Bury, Lancashire
Volume:    8c
Page:    353

Aged 13 in 1841 (so not twins)
Aged 25 in 1851

Recorded as same age as brother Peter in 1851 (i.e. a twin), but not a twin from the 1841 census.  However, baptisms together suggest they were twins.

Name:    Jacob Mather
Baptism Date:    3 Dec 1826
Baptism Place:    Turton, St Anne, Lancashire, England
Father:    Isaac Mather
Mother:    Sarah Mather
Reference Number:    GB127.L98/1/3/1

Not died in 1864

MATHER, JACOB        64 
GRO Reference: 1864  S Quarter in LIVERPOOL 
Volume 08B  Page 209

Aged 12 in 1841

Name:    Jane Mather
Baptism Date:    2 Jan 1831
Parish:    Turton, Lancashire, England
Father:    Isaac Mather
Mother:    Sarah Mather
Register Type:    Bishop's Transcripts
Reference Number:    Drm/2/40

Father's Occupation: Farmer
Abode: Entwistle

No baptism for Sarah, unless she was recorded as Reuben in error, (of Isaac and Sarah of Entwistle, born 11 Dec 1832, bap. 2 Feb 1834). 

Name    Reuben Mather
Birth Date    11 Dec 1832
Birth Place    Entwistle, Lancashire, England
Event Type    Baptism
Father    Isaac Mather
Mother    Sarah Mather
Baptism Date    2 Feb 1834
Baptism Place    Edgworth, Lancashire, England
Denomination    Independent
Piece Title    Piece 1038: Edgworth (Independent), 1807-1837

Aged 8 in 1841 (with parents)
Aged 15 in 1851, born Harwood (with parents)