As I've mentioned before, I like receiving letters and emails from readers. Sometimes they are a little strange , but often they are just pleasant thank-yous. And then there are the quibbles. I received from my publisher the other day what they referred to as a piece of fan mail. But it wasn't what I'd call fan mail. It was a quibble. These happen when you get something small wrong. And of course this always happens somewhere in a book. It happens most often when I write something 'obvious' from memory, or commit an elementary slip where my fingers are busy without my brain being engaged. (I once said an alpha particle was a hydrogen nucleus, instead of a helium nucleus. It is a big mistake in a sense, but it was a small slip in terms of not watching those fingers.) Sometimes you want to say 'Get a life,' but  just occasionally you can get one up on the quibbler. In this case, an ex airline employee was taking umbrage with something I'd said about tu...