From Darwin’s Beagle Diary, 1st April, 1832:
All hands employed in making April fools. — at midnight almost nearly all the watch below was called up in their shirts; carpenters for a leak: quarter masters that a mast was sprung. — midshipmen to reef top-sails; All turned in to their hammocks again, some growling some laughing. — The hook was much too easily baited for me not to be caught: Sullivan cried out, “Darwin, did you ever see a Grampus: Bear a hand then”. I accordingly rushed out in a transport of Enthusiasm, & was received by a roar of laughter from the whole watch. —
They must have had a whale of a time aboard HMS Beagle.
I love the phrase "I accordingly rushed out in a transport of enthusiasm" I wonder if people actually spoke in that manner or if it was an affectation of his writing style. Seems from the content that April fools jokes have been around for a while. Always thought most of them quite silly.
Probably biblical influence - see "Transport of delight"...
So, did he see the Grampus?
You'll just have to read the rest of his diary to find out.