When asked "If you were stuck on a desert island
and you could bring only one book
with you, what would it be?", chess champion John Nunn
replied "How to build a boat
I like this answer. But I myself would turn down a book as long as I could bring an extremely fine measuring ruler, an extremely fine pencil, and a small piece of paper. Provided whoever is putting me on this island all alone with nobody to talk to allows me this one favour, I would be able to effectively bring the entire Encyclopedia Brittanica. Do you want to know how? Well I will tell you.
First of all, come up with a system of associating each character that might appear in the encyclopedia with a two digit number. Spacebar is treated as a character. Whatever system you like. Now, go through the encyclopedia starting at page one and start converting the characters, in the order they appear in the encyclopedia, into these two digit numbers.
When you are finished, you have a really big number. But by putting a decimal point in front of this numerical monstrosity, you end up with a number between zero and one. Call this number x.
Now pull out your trusty ultra-fine ruler and pencil and (carefully now) draw a line of x centimetres. Or x inches if you are from the United States or some other country that has not yet realised that the metric system exists. Quarter pounder with cheese. What are you people thinking?
So now you have your small piece of paper with all the info you need and you are ready to be thrown on that island. Remember to bring your ruler because when you get there you are going to need to convert the distance of the line back to that long string of numbers. Then convert the string back into the encyclopedia. Enjoy.