NavList:

Lots of good material in that old book!! Later editions are edited and re-written by other authors. That's not necessarily bad if you're looking for advice from a specific decade. But for Lecky's original prose, there's really no substitute. Three weeks ago I wrote:
"Lecky's Wrinkles in Practical Navigation is a must-read. Lecky describes the state of navigation in his era and provides extensive practical advice still useful to navigators today. His writing style is humorous and clear:
Lecky's Wrinkles 1884 "

You wondered abou the meaning of "wrinkles". It's in the usual English sense of "details" similar to an expression like "ins and outs". Celestial navigation is like the game of golf. You can have fun and learn to putt and bang the ball a few dozen yards down the fairway on day one, and yet you'll still find something new to refine your game and enjoy it again (and buy toys to suit your growing budget) years later. We start with the basic strokes and get to all the wrinkles later. I suspect that this is more common in British English, but it still works in American English. An online definition offers this as a second "informal" definition of the word: "a clever innovation, or useful piece of information or advice. 'learning the wrinkles from someone more experienced saves time' ". 

Frank Reed
Clockwork Mapping / ReedNavigation.com
Conanicut Island USA

By the way, I don't golf. I originally heard this analogy from the late Ken Gebhart in one of his quickie "intro to celestial" talks at a boat show in Chicago about fifteen years ago. It's apt!