I'm only posting this because this Isaac Emerson was also baptized in St Mary's too!!
Children of John and Mary Jane Emerson
It was thought there were eight children but only three had been definitely located, with two probables. Further information came to light in 2007 in the form of an extract from pages 151 and 152 of The English Emersons: A genealogical historical sketch of the family from earliest times to the end of the seventeenth century, including various modern pedigrees, with an appendix of authorities , by Peter Henry Emerson, published in London by D Nutt, 1898, deluxe edition, limited to 50 copies ('the book') (email 24 Apr 2007). It gives a list of 10 children, and appears to have been contributed by Frances Wetheral Mulock or Frances Anne Emerson (the first is referred to as 'myself', the second is the name of the person who signed the contribution, which is dated Clarina, July 17, 1896). The order of the children below is the order in the book.
1. Horatio Emerson, the eldest son, was born 9th May 1851 and so was also the oldest child. He was living at Greenfield in Sutton in 1873 but nothing else is known about him, though, since his younger brother sold Greenfield in 1885, he may have died before that date, in his early 30s. The book says Horatio died young. Richard Emerson's tree (email 31 May 2008) says he lived from 1853 to 1877. Frances Emerson (Richard Emerson email 3 Jun 2008) says he died in Leitton [sp?] outside Dublin from inflamation of the lungs, aged 26, never married.
2. Isaac Bomford Emerson, b 17 Dec 1852, baptised 27 May 1853 from 5 Cabra Parade (St Mary parish records, Dublin), d 1950. Isaac Bomford Emerson was married twice: first to Minnie Wylie, daughter of the late John Wyley of Leacroft, Isle of Wight; and second to Alice Emily Tait or Alise Emily Tait, d February 1944, daughter of Sir Peter Tait of Limerick. It appears he had issue with the latter. Roll of Commissioned Officers in the Medical Service of the British Army, b y William Johnston (1917, The University Press) notes ' Isaac Bomford Emerson. S. 4 Feb. 1877. SM 4 Feb. 1889. S. Lt. Col. 4 Feb. 1897' (Google Books). "I remember Uncle Isaac very well. He and Aunt Alice came to stay at Woodlands. He was very tall and fair, and I remember both daughters who had just returned from Italy where they had been studying music"
http://www.bomford.net/IrishBomfords/Chapters/Chapter27/Chapter27.htm#27.4.1%C2%A0_Marriage_Settlement_%E2%80%93_Mary_Jane_and_John_Emerson%C2%A0_6th_March_1850_