When I look at the tracks of a bicycle in the snow and estimate its speed, it is something I learnt from the KnowHow Book of Spycraft. Even today this book and the related “Usborne Spy’s Guidebook” are well worth a flick through, especially if you want to inspire a youngster to noticing more than their phone.
The reason I recalled this book is that it contained the following page:
The system is less like British Finger Spelling than I had thought. Some of the single-handed signals have potential as useful supplements to the AMA symbols we have already learnt. For example, “Echo”, “Foxtrot”, “Mike”, “November” and possibly “Uniform” will all be clearer over a greater distance than standard AMA signs. “Juliet” can be made with less hand movement, although I would suggest this is always made with the four fingers raised to distinguish it from the standard “Lema” gesture.