birthyear = 1838 Probable birth record, Q3 1938 (see FreeBMD.org. 
deathyear = 1905 Death registration, aged 66, Q2 1905 (see FreeBMD.org and Ancestry.co.uk

sources

death

FreeBMD

Name: James Roberts Brown
Age: 66
Death Registration Place: Kensington, London, United Kingdom
Death Date: Jun Q. 1905
Volume: 1a
Page: 123

burial

Deceased Online Burial Indexes

Name: James Roberts Brown
Register Type: Burial
Death Date: abt 1905
Burial or Cremation Date: 27 Apr 1905
Burial or Cremation Place: Camden, London, England
https://www.deceasedonline.com/servlet/GSDOSearch?DetsView=Summary&src=ext&fileid=14359503

probate

Calendar of the Grants ...

Name: James Roberts Brown of 44 Tregunter-road South Kensington
Death Date: 23 Apr 1905
Death Place: Middlesex, England
Probate Date: 17 May 1905
Probate Registry: London, England
to Sarah Phoebe Brown

marriage

The Belfast Newsletter (Birth, Marriage and Death Notices)

Name: James Roberts Brown
Gender: Male
Notice Type: Marriage
Residence Place: N W
Marriage Date: 4 Jun 1874
Marriage Place: London, England
Father: John Brown
Spouse: Sarah Phoebe Phillipps
Publication Date: 10 Jun 1874

BROWN--PHILLIPPS--June 4, at St. Peter's Belsize Park, London, James Roberts Brown, F.R.G.S., 84 Caversham Road, N.W., youngest son of the late John Brown, F.R.G.S., F.R.S.N.A, Soalbey Lodge, Camden Road, to Sarah Phoebe, eldest daughter of Richard Phillipps, 53, Belsize Park, Gardens, London.

census

1871 England

Name: James R Brown, diamond merchant
Age: 32
Relation: Lodger
Gender: Male
Where born: London England
Civil parish: St Marylebone
Ecclesiastical parish: All Souls
Registration district: Marylebone
Sub-registration district: All Souls
ED, institution, or vessel: 9
Household schedule number: 432
Piece: 151
Folio: 30
Page number: 53
Household Members (Name) Age Relationship
Mary A Wymer 50 Head
Mary A Wymer 27 Daughter
Alice Kemp 3 Visitor
James R Brown 32 Lodger
Rofferton Bonte 52 Lodger
Phillip Boyd 25 Lodger
Henry B Hayet 27 Lodger
Edward J Huller 32 Lodger

1881 England

Name: James R. Brown
Age: 42
Relationship to Head: Head
Spouse: Sara P. Brown
Gender: Male
Where born: London, London, Middlesex, England
Civil Parish: Islington
County/Island: London
Country: England
Street Address: No 14 Hilldrop Rd
Marital status: Married
Occupation: Diamond Merchant
Registration District: Islington
Sub registration district: Islington West
ED, institution, or vessel: 59
Neighbors:
Piece: 242
Folio: 123
Page Number: 26
Household Members:
Name Age
James R. Brown 42
Sara P. Brown 39
Leonard J. P. Brown 4
Geoffrey A.P. Brown 2
Marie Bangert 23
Sarah Gibbons 22
Mary Silcot 18

1901 England

Name: Jas R Brown
Age: 62
Relation to Head: Head
Gender: Male
Spouse: Sara P Brown
Birth Place: Clerkenwell, London, England
Civil parish: Kensington
Ecclesiastical parish: St Luke Radcliffe Square
Registration district: Kensington
Sub-registration district: Brompton
ED, institution, or vessel: 18
Neighbors:
Piece: 36
Folio: 197
Page number: 76
Household schedule number: 675

web

Sherborn, C. W. (Charles William). James Roberts Brown. FRGS. FAI. PPOV. FRSNA. CopenhagenConstante et Fidele. [1890]. Retrieved from the Digital Public Library of America, http://search.openlibrary.artstor.org/object/SS7729421_7729421_643539_DELW. (Accessed December 31, 2022.)
Correspondence Addressed to John Brown, FRGS and His Son James Roberts Brown, FRGS