I have checked the Dublin Voting registers 1837 and there are a couple of John Martin. Here goes
John Martin, 17 Great Britian street, Shop and Premises.
John Martin, Provision dealer, 24 south Great Georges Street
John Martin, Skinner, 10 Wesling street (a little hard to see this one)
John Martin, Vinter, 119 North Kings street
John Martin, esq, North Wall
John Martin, Cornfactor, 12 New Church St
John Martin, Merchant, Blackbush, Co.Dublin, had premises at 29 college Green