NavList:

I wrote earlier:
"A century also implies nearly one degree of precession, and that's enough to cancel the implied precision of those finely divided scales and pointers."

Sorry. That was an editing error on my part. I should have said "more than one degree". We get a degree of precession every 72 years or so. Assuming the originals --the masters from which some of these modern star globes are still produced-- date from before about 1952, then the modern products can be in error by one degree or more.

Could be worse, of course! If you attempt to use an all-sky star chart printed c.1750 prepared from Flamsteed's finished star catalog, the error from precession would amount to nearly 4°. Unlikely in the real world... :)

Frank Reed