THE ELECTROMAGNETIC SPECTRUM
eighteen decades of frequency · and how much of it the eye sees
RESISTOR COLOUR CODE
the bands, the tolerances and the preferred series of two standards
THE SAFFIR-SIMPSON SCALE
five categories of hurricane wind — and how much more damage each next one does
SPEED THRESHOLDS
six thresholds where a different physics begins · every figure computed, not typed
WHAT A TORNADO BREAKS
twenty-eight damage indicators — and the wind at which each one gives way
CROCHET SYMBOLS
the standard chart symbols, abbreviations and US/UK name differences — per the Craft Yarn Council standards
MORSE CODE
26 letters and 10 digits · dot, dash
PHONETIC ALPHABET
the ICAO standard · for radio and telephone
FLAG SEMAPHORE
two flags, eight positions 45 degrees apart — all 26 letters; after the numerals sign A–I read as 1–9 and K as 0
MARITIME SIGNAL FLAGS
the twenty-six alphabet flags of the International Code of Signals — and what each one means alone
NUMERAL PENNANTS AND SUBSTITUTES
how to fly the same flag twice in one group with only one set aboard
BISHOP
a diagonal at any distance — and the half of the board that will never come