Flint's Pocket Reference Book
By Thomas J. Glover
A real mine of information packed into 768 pages and yet still in a pocket size so you can cheat at pub quizes.
It has conversion tables for just about everything, trig formulas, ice strengths, first aid, rope breaking loads, crane drivers signals, knots and even chilli strength tables!
Just the book to get you out of trouble. Very highly recommended.