[3] In Dublin, he studied medicine at the Meath Hospital, and later utilised his medical ability on Anthony Norris Groves' pioneering mission to Baghdad, Ottoman Empire – after the death of his first wife in 1829, Cronin went with Groves to administer medical support including dealing with an outbreak of plague.
[6] He was a member of the English Homeopathic Association, and in 1858 he became the last man to become a Lambeth MD before the Medical Act 1858 abolished this particular qualification.
[8] Originally a Roman Catholic, when Cronin moved to Dublin he sought membership with various dissenting churches in the area but was only admitted as a visitor.
When a number of members of a failing assembly at Ryde had stopped attending the meeting, he travelled down and met with some of them and celebrated the Lord's Supper.
A furious row erupted with different assemblies disagreeing about which side was right and therefore to be supported, with Darby, who had privately sympathised with him, attacking him in the strongest terms.