@Setanta,
Interestingly, in many of the books on Darwin, his position
of ships naturalist was taken as a fact, and as you said, that was incorrect.Actually, it was John Henslow, his geology mentor at Cambridge , advising George Peacock, another "Natural Philosopher", who had responsibilities to the Admiralty to actually place "Naturalists" on British ships.These two "greased the skids for DArwin"
In the case of the
Beagle the Admiralty ws looking more for a companion for Capt Fitzroy, who was only 26 when he assumed command.
The Admiralty was delighted that Fitzroy would have "A well-bred gentleman " to be that companion and " relieve the isolation of command and share the captains table".
The "fix" was in for Darwin because PEacock nd Henslow conspired with the Admiralty "Hydrographer" (what they called their map making service during that age) PEacock was drinking buds with that guy, a CApt Francis Beaufort .
In fact, as part of the requirements of the sailing, Darwin's collections, (if he were the official naturalist of the voyage) would become the property of the Qdmiralty. Beaufort stated in the commission that
1Darwin was free to leave the voyage wherever he felt necessary (Fitzroy, on meeting him wasn't so sure that Drwin would even last the trip.
and
2Darwins collectibles were his own property so long as he gave them to a "worthy public body"
Actually Fitzroy had promised the post to a personal friend, and told Darwin that when they first met at Beauforts offices. Darwin then gave up on going and(I believe from reading Desmond) that the Admiralty asked Fitzroy to give up the invitation he made to a friend and consider Darwin instead .
SO Fitzroy and Darwin, nowofficially shipboard companions, didn't start out on a really good foot . Darwin ws actually allowed to provision the ship with geology crap and tools , as well as naturalists materials (boxes, paper, string, all for packing and shipping collections back to England)
AND to top it off, Darwin hired his own collector and servant, Sims Covington who would eventually actually do the collecting according to whatever Darwins had planned.
Meanwhile the ships surgeon Robt McCormack, the real naturalist, was apparently more attuned to navigation and "place settings at the captains table" rather than care about being a naturalist so most of the actual science was, indeed, left to Darwin by default (The exception was that ,McCormack was getting paid and Darwin hd to shell out about 500 quid for the "opportunity" to be part of the voyage.