He was at sea again soon after his marriage as commander of the _Beaver_
sloop, in which commission he was sent to mount guard over Napoleon at
St Helena until his death. He took a sketch of the dead emperor in full
profile, which was engraved in England and France, and considered a
striking likeness. He was meanwhile no doubt perfecting the code of
signals for the use of merchant vessels of all nations, including the
cipher for secret correspondence, which was immediately adopted, and
secured to its inventor the Cross of the Legion of Honour from Louis
Philippe. It was not actually published in book form till 1837, from
which date its sale produced an appreciable income.

After returning in the _Rosario_ with the despatches concerning
Napoleon's death, he was sent to escort the body of Queen Caroline to
Cuxhaven. He was then told off for revenue duty in the Channel, and had
some smart cruising for smugglers until the _Rosario_ was pronounced
unseaworthy and paid off on the 22nd of February 1822. As a result of
this experience he wrote a long despatch to the Admiralty, in which he
freely criticised the working of the preventive service, and made some
practical suggestions for its improvement. In 1822 he also published
_Suggestions for the abolition of the present system of impressment in
the Naval Service_, a pamphlet which is said to have made him unpopular
with Royalty. He frequently in his novels urges the same reform, which
he very earnestly desired.

He was appointed to the _Larne_ in March 1823, and saw some hard service
against the Burmese, for which he received the thanks of the general and
the Indian Government, the Companionship of the Bath, and the command of
the _Ariadne_. Two years later, in November 1830, he resigned his ship,
and quitted active service, according to Mrs Lean, because of his