Hello Philip,
Carol Gosselin kindly looked up the 1900 US census for us which includes month and year of birth, but no Thomas Joughin found. She did find the death cert of the Thomas Joughin who died in 1909, but he was not the IOM one, as Averil wrote.
She sent the actual cert which has a few more details. He died of TB, and the person supplying the information was Louisa Joughin, who I thought might be his wife, as he was recorded as married.
Would you like me to send you the scan?
Perhaps Louisa didn't know where Thomas's father was born if he had died before her marriage? (Or perhaps he really was born in Ohio.)
Sue