Snark mark 2/5:
Its habit of getting up late you’ll agree
That it carries too far, when I say
That it frequently breakfasts at five-o’clock tea,
And dines on the following day.
In November 1859, Dodgson gave a lecture at a meeting of the Ashmolean Society on “Where does the Day begin?”. A clock traveling around the earth with the sun always exactly above of it could stand still but always would be correct. (It’s almost like the mad tea-party having always six o’clock while moving around the table.) Only the day date suddenly would change somewhere. (That’s where in Alice’s Adventures in Wonderland the March Hare quickly changes the topic.)
There neither were internationally defined time zones yet, nor an internationally agreed date line when Charles Darwin and the HMS Beagle travelled around the world, but when he (and the Snark) breakfasted in Tahiti, it probably already was around tea time back home in Carroll’s Oxford. From England it carries us far away, when we imagine breakfasting in Tahiti.
On 2020-10-22 I found a twitter thread, where John Pretorius showed, that he interpreted (and applied) Lewis Carroll’s “breakfasts at five-o’clock tea” stanza in the same way as I did.
Discussion: Facebook | Twitter 
2019-08-16, updated 2021-03-20
Here I inserted (2012-08-18) details from Henry Holiday’s Snark illustrations to the 1st Snark fit into Thomas Landseer’s illustration.
You can use the assemblage in compliance with license CC BY-NC-ND 4.0. Main artists: Conrad Martens & Thomas Landseer, Henry Holiday & Joseph Swain.
more (with a high resolution image) | search “SnarkAssemblage”
2017-09-23, update: 2020-01-30
- [left]: Illustration The Crew on Board by Henry Holiday to Lewis Carroll’s The Hunting of the Snark (1876)
- [right]: Crossing the Line (1839), based on a print by Thomas Landseer, after Augustus Earle. You will find the print in Robert Fitz-Roy’s Narrative of the surveying voyages of HMS Adventure and Beagle, Vol II (1839).
This is of of the comparisons where am not so sure whether Holiday alluded to Landseer’s print. If it is, then you might wait a little bit before you look at my spoiler where I marked possible(?) clues given to us by Holiday.
2017-11-08, updated: 2019-06-16
Monsters, by Henry Holiday (left) and J. J. Grandville (right).
[…] One of the first three [illustrations] I had to do was the disappearance of the Baker, and I not unnaturally invented a Boojum. Mr. Dodgson wrote that it was a delightful monster, but that it was inadmissible. All his descriptions of the Boojum were quite unimaginable, and he wanted the creature to remain so. I assented, of course, though reluctant to dismiss what I am still confident is an accurate representation. I hope that some future Darwin in a new Beagle will find the beast, or its remains; if he does, I know he will confirm my drawing. […]
(Henry Holiday (1898): The Snark’s Significance)
Once you meet the Boojum, you might be Going Slightly Mad.