[1] In August 1831 Caffin passed his examination, and in October 1834 was appointed to the shore establishment (or "stone frigate") HMS Excellent, then recently organised as a school of gunnery.
He was appointed, together with an artillery officer, to investigate and report on a celebrated claim to invention, Samuel Alfred Warner's "Long Range" secret weapon.
[1] In February 1845 Caffin was one of a commission for experimenting on the relative merits of paddle and screw; and their report paved the way for the general introduction of the screw-propeller into the navy.
He had previously, 2 December 1865, attained his flag-rank, but, not having served his time at sea, was placed on the retired list, on which he duly advanced to the higher grades—vice-admiral, 2 November 1871, and admiral, 1 August 1877.
His son Crawford, a commander in the navy, received his promotion for his services in the transport department during the Anglo-Zulu War in 1879.