Robert Bell Sedgwick  [Alfred Blair Sedgwick / Sophia Julia Bell
b. b. October 11, 1849, St Pancras, Midddlesex, England2,4c,5
d. bet 1900-1910, [Brooklyn, Kings, New York]1
m. abt 1882, Henrietta A Rogers1

Henrietta A Rogers  [Unknown Rogers / Henrietta Unknown1]
b. July 1865, Connecticut1

Census records:

1860 NY Kings, Brooklyn
1870 NY Kings, Brooklyn
1880 NY Kings, Brooklyn
1900 NY Kings, Brooklyn
Widow Henrietta
1910 NY Kings, Brooklyn

Note that Robert's age as given in the ship's manifest upon their arrival in the US does not agree with his correct age according to the birth records. However, in the 1900 census he also stated that he was born in 1849.

I saw a line at FamilySearch.org that shows Henrietta Rogers descended from "Thomas The Pilgrim ROGERS" of the Mayflower.

Children:

Robert Blair Sedgwick1
  b. March? 1885, [Brooklyn, Kings,] New York1
  m. 1912, Westchester County, New York,8 Edith D Hetzel1,3a
Amy R Sedgwick
  b. Jun 1886, [Brooklyn, Kings,] New York1

Sources:

1. Census records, any of those indicated.

2. New York Passenger Lists, 1851-1891
an Ancestry.com database
Manifest of ship Margaret Evans upon arrival New York, October 18, 1851

3. Descendant or Researcher of this Family
a. Martha Sedgwick, granddaughter of Robert B Sedgwick, Jr.

4. SedgwickUK.org, by Nicky Cunningham
a. Web page for this family: Alfred Blair Sedgwick and a linked page
b. Transcript of Sedgwick Entries in English Marriage Registers 1837 TO 1846
these records:
[name]PERIODDISTRICTIGIPARTNERPARISHDATE
ALFRED BLAIR SEDGWICKDecember 1840St Jas Sq WestYHarriet NewtonWestminster (M147517)23/12/1840
c. Transcript of Sedgwick Entries in English Birth Registers 1847 TO 1850
these records:
[name]PERIODDISTRICTIGIFATHERMOTHERPARISH
SOPHIA ELLEN SEDGWICKMarch 1848St PancrasYAlfred Blair SedgwickSophia JuliaSt Pancras (C047935)
ROBERT BELL SEDGWICKDecember 1849MaryleboneYAlfred Blair SedgwickSophia JuliaSt Pancras (C047935)

5. Parish registers of St. Pancras Old Church, 1660-1916 Church of England
LDS Microfim #0598168, extracted recordes viewed at FamilySearch.org
this record:
  ROBERT BELL SEDGWICK
  Birth: 11 OCT 1849
  Christening: 01 JAN 1850 Old Church, Saint Pancras, London, England
  Father: ALFRED BLAIR SEDGWICK
  Mother: SOPHIA JULIA

8. Westchester County [New York] Archives
Marriage Records, 1908-1930, Personal Name Index
this record:
LastNameFirstNameCertificateNoYear
SedgwickRobert93021912
HetzelEdith93021912